Dr Yoshifumi Futaana (IRF-K), Energetic Neutral Atoms around Mars - Latest results from NPD on board Mars Express. [Abstract]
2 Dec.
Dr Peter Dalin (IRF-K), Part I. Case study of the role of neutral air turbulence in the PMSE variations. Part II. Concept and technique for the processing of NLC digital photographs. [Abstract]
25 Nov.
Andreas Ekenbäck (IRF-K), Using the Flash code for MHD simulations - description of a testcase. [Abstract]
12 Nov.
Tomas Hode (Swedish Museum of Natural History), Astrobiology missions to Mars. [Abstract]
11 Nov.
Prof. Sheila Kirkwood (IRF-K), Polar Mesosphere Winter Echoes - new results from statistics and from radar interferometry. [Abstract]
9 Nov.
Docent Jan-Erik Wahlund (IRF-Uppsala), The latest news from Titan.
4 Nov.
Prof. Anatol Guglielmi (Institute of Physics of the Earth, Moscow), Ponderomotive forces in space physics. [Abstract]
2 Nov.
Prof. Syun-Ichi Akasofu (International Arctic Research Center, Alaska), Long-standing unsolved problems in solar physics and magnetospheric physics. [Abstract]
29 Oct.
Prof. Martin Friedrich ( Tech. Univ. Graz), A recent model of the lower ionosphere based on sounding rocket and EISCAT observations and neural network analysis.
28 Oct.
Grigory Nikulin (IRF-K), Internal-gravity and Rossby waves. [Abstract]
21 Oct.
Dr Masatoshi Yamauchi (IRF-K), Concentration of Aurora Arc from viewpoint of Alfvén wave reflection at Ionosphere. [Abstract]
30 Sept.
Dr Shu T. Lai (Air Force Research Laboratory, Space Weather Center of Excellence), High-Level Spacecraft Charging at Geosynchronous Altitudes: A Statistical Study. [Abstract]
9 Sept.
Prof. Sandra C. Chapman (Univ. of Warwick, UK), PIC Simulations of Reforming Quasiperpendicular Collisionless Shocks - Consequences for Particle Acceleration. [Abstract]
9 Sept.
Prof. Sandra C. Chapman (Univ. of Warwick, UK), Complexity, Models, Methods, and Examples from Plasma Physics and Astrophysics.
Abstracts
Prof. Sandra C. Chapman (Univ. of Warwick, UK), PIC simulations of reforming quasiperpendicular collisionless shocks - consequences for particle acceleration.
It has been suggested that supercritical shocks provide a variety of
mechanisms for particle acceleration leading to cosmic ray generation. PIC
simulations of quasiperpendicular shocks have recently shown that for
certain parameters the shock solution is no longer static- as found in
previous Hybrid simulations- but rather reforms on the gyroscales of the
ions. These parameters, in particular low upstream proton thermal speed as
compared to the inflow speed, are favoured at SNRs and at the heliospheric
termination shock. This talk will focus on the initial stages of particle
acceleration in reforming shocks from the background to a suprathermal
\'injection\' population which can then Fermi accelerate to cosmic ray
energies.
Dr Shu T. Lai (Air Force Research Laboratory, Space Weather Center of Excellence), High-Level Spacecraft Charging at Geosynchronous Altitudes: A Statistical Study.
The onset of spacecraft charging at geosynchronous altitudes occurs at a critical value of the space plasma electron temperature for a given spacecraft surface. We review the theoretical formulation and computational results and compare the results with the Los Alamos National Laboratory spacecraft charging observations. The observations show that the onset of charging occurs at a critical temperature in almost every charging event, no matter which satellite, which year, and which month. It is also observed that the critical temperature values remain the same no matter in eclipse or in sunlight.
Dr Masatoshi Yamauchi (IRF-K), Concentration of Aurora Arc from viewpoint of Alfvén wave reflection at Ionosphere.
[past observation]: While it is well known that the aurora activity is strongly controlled by the solar wind input, not all the controlling factors of actual aurora intensity, even the statistical one, is not well known. One obvious controlling factor is the ionospheric conductivity. High conductance (summer) favors large potential drop over the polar cap and total current intensity [e.g., Fujii et al., 1981; Fujii and Iijima, 1987; Yamauchi and Araki, 1989; Lu et al., 1994] and subsequent joule dissipation. However, peak density of the field-aligned current is higher during low conductance in winter [Newell and Meng, 1996].
[my model #1]: Using simple wave reflection model [Sato and Iijima, 1980; Kan and Sun, 1985], I have simulated the effect of local conductivity enhancement due to the field-aligned current (this represents the precipitation). Just including the conductivity enhancement into the linear wave reflection system, we can include the positive feedback of the enhancement of ionospheric conductivity and intensification of field-aligned current through the conductivity gradient. The simulation shows larger localization of the field-aligned current for low background conductivity because the ratio between the enhanced conductance and the background conductance is larger for low background conductance.
[my model #2]: In addition I made a simple calculation to examine the seasonal (ionospheric conductivity) effect on the ionospheric joule dissipation. Since the decay time of the magnetospheric energy is counter proportional to the total dissipation by the both hemispheres, this has clear semi-annual peak. Since input energy to a given point is proportional this decay time multiplied by the local conductivity, we can easily predict the famous semi-annual variation of nightside geomagnetic activities (in Kp and AL indices) and annual variation of dayside activity even if we ignore the semi-annual variation of energy input from the solar wind by the geometrical effect (Russell-McPerron effect).
Prof. Anatol Guglielmi (Institute of Physics of the Earth, Moscow), Ponderomotive forces in space physics.
This report consists of two parts. The first part in effect answers the question: Why is it in many cases preferable to use ponderomotive forces instead of the Lorentz force in space physics, especially when studying the acceleration of ions by electromagnetic waves? We shall consider the Abraham, Barlow, Lundin-Hultqvist, and Miller ponderomotive forces, as well as the so-called Bolotovsky-Serov ponderomotive drift. The second part is devoted to some interesting manifestations of the ponderomotive forces in space plasmas acceleration of the polar wind and deceleration of the solar wind, plasma cavity formation, anharmonicity of the standing Alfvén waves, resonant acceleration of heavy ions, etc. The most important conclusion is that ponderomotive acceleration of ions by Alfvén waves is a fundamental process in terrestrial magnetospheric- and celestial plasmas. Ponderomotive acceleration may transfer energy and momentum to plasmas, leading to plasma outflow at small- as well as large scales in space.
Grigory Nikulin (IRF-K), Internal-gravity and Rossby waves.
Motivations for this seminar came from the Geophysical and
Environmental Fluid Dynamics summer school (Department of Applied
Mathematics and Theoretical Physics, University of Cambridge) which I
visited in September. Internal-gravity and Rossby waves are common
waves in oceans and the atmosphere but have different restoring forces
and scales. The restoring force for Rossby waves is the variation with
latitude of the Coriolis force while for internal-gravity waves it is
the gravity force. In the atmosphere these waves transfer momentum
from the troposphere to the stratosphere and mesosphere influencing
the atmospheric circulation on different temporal and spatial scales.
I will give a theoretical background for both kinds of waves in
combination with very good visualizations from laboratory experiments
and computer demonstrations that I have done in the summer school.
Prof. Syun-Ichi Akasofu (International Arctic Research Center, Alaska), Long-standing unsolved problems in solar physics and magnetospheric physics.
Like any field of science, there are a number of long-standing, unsolved problems in solar physics and magnetospheric physics, and their solutions are considered to be almost beyond the capability of the present generation of researchers. However, it is suggested that some of the unsolved problems have remained unsolved because the guiding concepts or paradigms have no sound foundation. In this paper, several paradigms are chosen for examination from this particular point of view. They are sunspots, solar flares/CMEs in solar physics, and the concept of magnetic flux transfer in the magnetosphere. It is obviously not the intent of this paper to provide answers to these difficult problems. Rather, by posing basic questions about the sources of the established paradigms, it is hoped that a new way of approaching the long-standing problems may be opened.
Prof. Sheila Kirkwood (IRF-K), Polar Mesosphere Winter Echoes - new results from statistics and from radar interferometry.
Polar mesosphere Winter Echoes (PMWE) is the name we have given to thin layers of enhanced radar echoes observed by the ESRAD 52 MHz and EISCAT 224 MHz radars from mesospheric heights during winter. Earlier observations of radar echoes from the winter mesosphere were made by the Poker Flat radar and the Alomar Sousy 50 MHz radars during the 1980s. At that time, it was assumed that the echoes were due to layers of turbulence in the neutral atmosphere. Our studies have shown that the radar echo strengths are too high for this explanation to be reasonable. We have further found that they appear at heights where no turbulence is expected (according to co-located meteorological rockets) and where lidars see anomalies in the light-scatter profile. A new statistical analysis of PMWE since 1997 will be reported which shows a substantial increase in PMWE ocurrence. Further, exceptionally strong echoes from 29 October 2003 have been analysed using interferometric methods. Those results show will also be presented.
Tomas Hode (Naturhistoriska riksmuseet), Astrobiology missions to Mars.
The current activity on Mars is in many aspects focused on questions related
to the possibility of past and present life on the red planet, but
investigating conditions for life is not the same thing as actually looking
for fossil or extant life itself. The next generation of Mars landers will
be aimed at investigating evidence for life, but such an endeavour will
require an entirely different setup of instruments, as well as an increased
knowledge of the geological history of Mars. In this talk I will discuss why
life may have existed on Mars, where we should look for it, and how that
search may be conducted in practical terms.
Dr Peter Dalin (IRF-K), Part I. Case study of the role of neutral air turbulence in the PMSE variations. Part II. Concept and technique for the processing of NLC digital photographs.
Part I. There are a lot of theoretical works showing that the neutral air turbulence can play a significant role in the creation of the polar mesosphere summer echoes (PMSE). At the same time the experimental works showed that the turbulence intensities are much too low to produce large radar scatters. On the other hand, some experiments revealed the cases that the regions of maximum radar backscatter correspond to the most unstable phase of gravity wave where the strong turbulence generation takes place. We have found several interesting cases supported the latter phenomenon. The regions of gravity wave propagations and strong wind shears (dynamical instability) coincide with the PMSE enhancements. It is clear that the neutral turbulence is not a dominant factor in the formation of PMSE layers, but the strong turbulent activity can certainly modulate the strength of radar signal on the pre-existing PMSE layers.
Part II. In the second part of my presentation I am going to talk about developing a concept and technique for the processing of digital photographs of noctilucent clouds (NLC). Up to now there are a lot of digital materials on the NLC appearance. The photo-registration of NLC can provide useful information on NLC characteristics, on the gravity and planetary wave activity in the mesopause. But at the same time there is absolutely no both a strategy and technique how to process the photos, to extract the parameters of noctilucent clouds and wave characteristics. I suggest the first version of a new concept and technique on the statistical research of noctilucent clouds with digital photographs.
Andreas Ekenbäck (IRF-K), Using the Flash code for MHD simulations - description of a testcase.
The seminar will describe the open source project FLASH and modifications done to the Flash code which make it possible to use it as an MHD simulation tool. The Flash code is a parallel application, written mainly in Fortran90, developed at University of Chicago. It uses the PARAMESH library to implement an adaptive computational grid. To investigate the possibility of using the Flash code as a general MHD simulation tool, a test case - the interaction between the solar wind and a comet - has been implemented and the seminar will present this implementation and the results therefrom. The possibility of generalizing the simulations to any object in the solar system will also be discussed.
Dr Yoshifumi Futaana (IRF-K), Energetic Neutral Atoms around Mars - Latest results from NPD on board Mars Express.
Energetic natural atoms (ENAs) around Mars are generated by interaction between the solar wind and the Martian exosphere. However, because the ENAs generated by the charge exchange of the solar wind protons have the same velocity as the solar wind flow, most of the ENAs are crashed into the Martian atmosphere. Several generation mechanisms of ENAs in space around Mars have been proposed. We devote our attention to the following two mechanisms: backscattered ENAs and subsolar ENAs.
The backscattered ENAs are generated at the top of the dayside exosphere, where the solar wind protons collide with the exospheric neutral particles and are scattered back as neutral atoms. The flux of the backscattered ENAs is expected to have solar zenith angle (SZA) dependence.
The subsolar ENAs are generated at around the subsolar point, where the solar wind flow is highly deflected from the Sun-Mars line. This means that a part of the deflected solar wind flow would experience charge-exchange and generated ENAs have different velocity of the undisturbed solar wind. The flow of the subsolar ENAs is expected to be an intense beam.
The Neutral Particle Detector (NPD) on board Mars Express obtains data around Mars from the beginning of this year (2004). We analyzed the data of NPD obtained in May and June and found the above-mentioned characteristics in the data. The observations and analysis are reported and the generation mechanisms of the Martian ENAs are discussed in this seminar.
Dr Uwe Raffalski (IRF-K), Odin’s future: STEAM ? - A new Swedish Satellite for the Investigation of Earth’s Atmosphere. [Abstract]
27 January (Tues.)
Dr Georgy Zastenker (Space Research Institute, Moscow), Review of some new solar wind features investigated by Interball project. [Abstract]
19 February
Dr Masatoshi Yamauchi (IRF-K), Wedge-like structured sub-keV ions inside the ring current region. [Abstract]
26 February (Aula)
Prof. Rickard Lundin (IRF-K), Solar wind removal of volatiles from celestial objects - perspectives on the Mars Express- and Rosetta missions. [Abstract]
4 March
Dr Alexander Kozlovsky (Sodankylä Geophysical Observatory), Response of Dayside Auroras and Ionospheric Plasma Flows to a Solar Wind Pressure Pulse. [
Abstract]
10 March (Wed.)
Dr Alexander Zakharov (IKI, Moscow), The PHOBOS-SOIL Project - Phobos Sample Return Mission.
11 March
Dr Edmond Murad (Air Force Research Laboratory, USA), Melting and Evaporation of Meteoroids. [Abstract]
25 March
Dr Evgenia Belova (IRF-K), Polar Mesosphere Summer Echoes and ionospheric heating: results and future plans. [Abstract]
15 April
Dr Vladimir Safargaleev (Apatity), The objectives and some preliminary results of EISCAT campaign on investigation of dayside auroras dynamics. [Abstract]
22 April
Dr Yasuhide Hobara (IRF-K), High Altitude Oxygen Outflow Observed by Cluster Satellites: Energization and Subsequent Wave Activities (Preliminary Results). [Abstract]
12 May (Wed.)
Sachiko Joko (IRF-K), The relations between geomagnetic activities and O+ outflows observed in the dayside magnetospheric polar region by Cluster/CIS (reversion of ICS-7 presentation). [Abstract]
24 May (Mon.), 11 am
Grigory Nikulin (IRF-K), The Mean Meridional Circulation and Wintertime Ozone Buildup in Midlatitudes. [Abstract]
27 May
Johan Arvelius (IRF-K), Simulations of a molecular sieve adsorption efficiency (DESCARTES).
3 June Postponed
Dr Tima Sergienko (IRF-K)
10 June
Dr Herbert Gunell (IRF-K), Solar wind charge exchange at Mars. [Abstract]
Abstracts
Dr Uwe Raffalski (IRF-K), Odin’s future: STEAM ? - A new Swedish Satellite for the Investigation of Earth’s Atmosphere.
The Odin satellite was launched on 20 Feb 2001 into a near polar orbit and is fully operational since. On 15 orbits a day measurements of a large number of trace gas constituents between 8 and 100 km are performed covering the latitude range 82°S to 82°N (in atmospheric mode). In astronomical mode it studies the physics and the chemistry of the interstellar medium by observing emission from key species. Odin is a Swedish-led mission in co-operation with Canada, Finland and France using sub-mm spectroscopy for astronomical and atmospheric studies. This is the first time sub-mm frequencies have been used from space for such studies. Earlier instruments such as the MLS instrument on NASA\'s Upper Atmosphere Research Satellite (UARS) and the MAS instrument on the Space Shuttle operated at mm-wave frequencies which limits their sensitivity and height resolution for a given antenna size. In addition to the Sub-mm Radiometer (SMR), an Optical Spectrometer and Infrared Imaging System (OSIRIS) is included in the payload to complement and enhance the atmospheric studies. OSIRIS is one of the first limb viewing spectrometers operating in scattered light.
The status of Odin is better than ever. However, even Odin will eventually die and new projects are coming up all the time. In 2002 the Swedish National Space Board sent out a call for ideas for future satellites and space missions. This led to a project called STEAM (stratosphere-troposphere exchange and monitoring), which received highest priority at SNSB. If this project gets funding this satellite will proceed the monitoring tasks of Odin. But it will also address scientific questions like the exchange of gases between the upper troposphere lower stratosphere region. Most important will be the water vapor transport which has significant importance on the future climate.
In my talk I will present the achievements with Odin as well as the ideas that make STEAM such an interesting project for the Swedish space activities.
Dr Georgy Zastenker (Space Research Institute, Moscow), Review of some new solar wind features investigated by Interball project.
Some new features of the solar wind were found in the INTERBALL project by comparison of the multipoint observations and using high-resolution plasma measurements onboard INTERBALL-1/MAGION-4 satellites. These results allow us to suggest some new concepts about solar wind in several points, namely:
- dimensions and persistent time of the middle-scale structures,
- large and very sharp plasma density changes on the borders of the small-scale structures,
- significant inclinations of many sharp plasma phase fronts,
- geoeffectivity of the sharp changes of the plasma dynamic pressure,
- not only magnetic field but also plasma in phase fast variations in the foreshock,
- large amplitude, low and high frequency plasma and magnetic field variations in the magnetosheath; their origin, dependence on IMF direction and comparison with MHD models.
Dr Edmond Murad (Emeritus, Space Weather Center of Excellence, Air Force Research Laboratory, Hanscom AFB, MA, USA), Melting and Evaporation of Meteoroids.
Meteors are by definition transitory phenomena arising from the entry of meteoroids in the Earth’s atmosphere. The meteoroids are small particles generally arising from the dust released by comets as they near perihelion. The dust, for the most part consists of silicates, some organic matter, and some water; the dust is released into a very cold environment (< 100 K), even though the temperature of the comet nucleus at perihelion may be as high as 330 K. As the orbit of the dust cloud intersects that of Earth, some of the dust is captured by Earth. The captured dust begins its fiery descent into Earth’s atmosphere, giving rise to the shooting star phenomenon. The shooting star phenomenon indicates that the temperature of the meteoroid is quite high – somewhat resembling an incandescent lamp. At that point most of the meteoroid material is evaporated. Between the point of capture and early descent into the atmosphere (say ~ 200 km) and the evaporation (when the meteoroid is incandescent) of the metals, a complex set of chemical processes occurs, despite the short transit time. I will talk during this seminar about phase transitions undergone by the dust material, eventual melting, and evaporation (or sublimation of the metals). I will briefly discuss how fractionation and possible formation of eutectic mixtures might affect the observed metallic species.
Dr Masatoshi Yamauchi (IRF-K), Wedge-like structured sub-keV ions inside the ring current region.
Structured dispersive sub-keV ions inside the ring current region (L=3 to 10), so called wedge-like dispersions, are surveyed using Viking, Freja, Munin, and Cluster satellites.
(1) What is the signatue, and why they are interesting (to me)?
(2) Patterns classification and statistics.
(3) Comparison to past simulation (based on long-time drift by ExB and grad-B drifts).
(4) correlation to the geomagnetic activity (past 12 hours).
(5) problems/puzzles (identification, composition, LT distribution,
substorm relation).
Prof. Rickard Lundin (IRF-K), Solar wind removal of volatiles from celestial objects - perspectives on the Mars Express- and Rosetta missions.
The Mars-Express and the upcoming Rosetta-missions are two important ESA-missions with major IRF involvement, scientifically as well as technically. A key science objective for both missions is to understand the evolution of celestial bodies in the solar system, in particular the question about source and loss mechanisms for volatiles. The solar wind interaction with the atmosphere/ionosphere of the Earth-like planets and comets represents an important loss process. The Earth-like planets, orbiting close to the Sun, are subject to a continued forcing by solar radiation - electromagnetic as well as corpuscular. Comets are in a similar manner subject to strong forcing during their perihelion passes. The solar forcing leads to escape of matter from the celestial objects by thermal (Jeans) escape and non-thermal (plasma) escape processes. The visible evidence for the erosion of matter from a comet is the long tail, specifically the plasma tail (ion tail). Thermal and non-thermal escape are both important, but non-thermal escape is more efficient as a loss process.
ASPERA on Mars Express will address new aspects of the non-thermal escape processes (ENA-imaging) but it will also enable a follow-up of our Phobos-2 findings on the \"planetary wind\" (plasma escape) from 1989. Moreover, ASPERA may or may not corroborate some controversial findings obtained from Phobos-2 (e.g. dusty plasma).
On board the Rosetta space probe, scheduled for launch on 26 Feb 2004, we have two IRF instruments, ICA (ion composition analyzer) and LAP (Langmuir probe), with the prime objective to study the solar wind interaction with comet 67P/Churyonov-Gerasimenko.
The escape of matter from a celestial body by non-thermal escape can be modelled from relatively simple energy and momentum considerations. We use Mars and 67P/Churyonov-Gerasimenko as typical targets for the solar wind energy and momentum exchange and compute the model escape of volatiles as a consequence of this interaction. The results from the model is interesting, indicating that solar wind erosion is sufficient in explaining the major erosion from non-magnetized objects in the inner solar system.
Key words: Solar wind, the atmosphere of planets and comets, plasma escape
Dr Alexander Kozlovsky (Sodankyla Geophysical Observatory, Finland), Response of Dayside Auroras and Ionospheric Plasma Flows to a Solar Wind Pressure Pulse.
Global ultraviolet auroral images from the IMAGE satellite are used to investigate the response of the dayside auroral oval to a sudden impulse (SI) in the solar wind pressure. The observations are supplemented by the TV all-sky camera images over Svalbard in the pre-non sector. We show that after the SI, new discrete auroral forms appear in the poleward part of the auroral oval so that the middle of the dayside oval moves poleward from about 70 to about 73 deg. AACGM latitude. This poleward shift started in the 15 MLT sector, then similar shift was observed in the MLT sectors located more westerly, and eventually the shift was seen in the 6 MLT sector. Thus, the auroral disturbance \"propagates\" westward (from 15 MLT to 6 MLT) at an apparent speed of the order of 7 km/s. We show that the above auroral disturbances are associated with the westward propagating convection vortex as inferred from the global convection maps produced by the SuperDARN HF radars. The poleward boundary of the auroral oval did not show any prominent motion associated with the SI. The optical and radar observations can be interpreted in terms of the pressure disturbance propagation through the magnetosphere at a velocity of the order of 200 km/s that is essentially slower than a magnetosonic (fast Alfvén) wave, and generation of a potential (curl-free) electric field in the wake of the disturbance. We suggest that the interchange instability is a possible reason for the development of discrete dayside auroral forms after the SI. We discuss the reasons for the slow propagation speed of the disturbance and for a vortex-like convection pattern associated with the auroral motions.
Dr Vladimir Safargaleev (Apatity), The objectives and some preliminary results of EISCAT campaign on investigation of dayside auroras dynamics.
The EISCAT experiment on study the dayside auroras over Svalbard was performed on 19-27 January 2004. Participants: Swedish Institute of Space Physics, Kiruna, Sweden (H Nilsson, T Sergienko), Sodankylä Geophysical Observatory, Oulu University, Oulu, Finland (A Kozlovsky), Polar Geophysical Institute, Apatity, Russia (V Safargaleev). We used ESR-32m antenna (pointed to west at 45 deg. elevation) to measure the plasma flow along East-West, and mainland UHF radar was pointed to north at low elevation (20 deg.) to observe the North-South plasma flow. The auroral activity was monitored by the PGI TV camera in Barentsburg and the FMI ASC camera in Longyearbyen. The data of the PGI induction magnetometer allowing the registration of magnetic field variations in the range of 0.1 ˆ 20 Hz were also available. Three intervals of auroral activity will be discussed: an auroral \"torch\" formation, the poleward displacement of auroras after IMF Bz turning northward and the PMAF event accompanying with electron density enhancement in EISCAT data and \"pearl\" type magnetic pulsations in magnetometer data. The possible interpretation will be suggested.
Dr Evgenia Belova (IRF-K), Polar Mesosphere Summer Echoes and ionospheric heating: results and future plans.
Polar mesosphere summer echoes (PMSE) are very strong radar returns that occur during summer months near the mesopause at high latitudes. They were discovered about 20 years ago. It seems that PMSE reflect complicated processes occurring in a multi-component plasma consisting of electrons, ions and charged aerosols and interaction between ionized and neutral atmospheric components. So far there is no clear and complete understanding the mechanism of PMSE. In order to influence the electron component during PMSE events, we conducted, in the summers of 1999, 2001, 2002 and 2003, joint PMSE/Heating experiments using the EISCAT VHF radar and the EISCAT Heating facility.
I will give a review of these PMSE and ionospheric heating experiments. Obtained results will be discussed and future plans will be presented.
Dr Yasuhide Hobara (IRF-K), High Altitude Oxygen Outflow Observed by Cluster Satellites: Energization and Subsequent Wave Activities (Preliminary Results)
Cluster spacecrafts observe high altitude ion outflow events rather frequently. In this report, we concentrate on one ion outflow event with a significant energization of oxygen ions in concert with Broad-band ELF emissions in April 2001 to study the relationship between high-altitude heavy ion energization and subsequent wave activities.
The outflow events are observed by two S/Cs for which CIS-CODIF measurements are available at high altitude polar cap region around 7.5 Re. The separation distances between the S/Cs are a few hundreds km. The energy spectrogram of oxygen ions shows an increase of their energies up to a few tens of keV from hundreds of eV within 30 seconds and wave equipments (EFW and STAFF) detect enhanced wave activities in the ULF/ELF range. During this event, hydrogen ions do not show the meaningful heating. Comparative analysis of temporal variations between particle characteristics (distributions, temperature, moments, energy flux etc) and wave properties (such as wave normal angle, polarization, and Poynting flux calculation) for three S/Cs will be performed to investigate the source mechanism and spatio-temporal characteristics of the oxygen ions and subsequent wave activities.
Dr Herbert Gunell (IRF-K), Solar wind charge exchange at Mars.
Wherever the solar wind meets a neutral atmosphere, X-rays are emitted by a charge exchange process between the neutrals and heavy solar wind ions.
A hybrid simulation of the solar wind-Mars interaction and a test particle simulation of heavy ion trajectories near Mars is used to compute the contribution from charge exchange processes to the X-ray emission from Mars. The results are compared to observations of X-rays from Mars made with the Chandra telescope (Dennerl, K., Astronomy & Astrophysics, vol. 394, pp. 1119-1128, 2002). The comparison indicates that the solar wind charge exchange process is a likely candidate for the production of the X-ray halo at Mars.
The calculations were performed in three steps. First the solar wind parameters were estimated from data obtained by the WIND spacecraft. Since Mars was near opposition the plasma that was sampled by WIND near the earth on 2 July 2001 arrived at Mars two days later during the X-ray observation. The data was scaled with the distance from the sun, and the average parameter values over the period of the observation were used as input parameters for a hybrid simulation.
The second step was running a hybrid simulation of the interaction between the solar wind and Mars to obtain the electric and magnetic fields around Mars.
As a third step a test particle simulation was run, calculating the trajectories of heavy solar wind ions in the electric and magnetic fields that were obtained from the hybrid simulation. The X-ray emission density was saved on a grid for each time step of the test particle simulation. A hundred thousand trajectories were calculated for each of ion species.
Sachiko Joko (IRF-K), The relations between geomagnetic activities and O+ outflows observed in the dayside magnetospheric polar region by Cluster/CIS (reversion of ICS-7 presentation).
The terrestrial-origin O+ ions outflowing in the dayside
high-altitude (from 3Re up to 11Re)/-latitude (from 70 to 90
degrees in invariant latitude, ILAT) polar region have been
observed by the CIS instrument onboard the Cluster satellite.
The statistics of polar outflowing O+ ions ((1) energy of max
number flux, (2) max number flux, and (3) number density) is
complied in terms of geomagnetic activities represented by
Kp index for global/planetary geomagnetic activity and ASY/SYM
indices for mid-latitude geomagnetic disturbances (instead of
AE and Dst).
It seems that O+ ions outflowing in the polar region respond
well to ASY/SYM indices rather than to Kp on (2) and (3)
according to on-going study.
Grigory Nikulin (IRF-K), The Mean Meridional Circulation and Wintertime Ozone Buildup in Midlatitudes.
Vertical residual velocities calculated from the quasigeostrophic
transformed Eulerian mean thermodynamic and continuity equations are used to study connections between the residual mean circulation of the stratosphere and wintertime midlatitude ozone buildup. We found agreement with theoretical considerations for November, January and February while there are no expected connections in December. Difference between months may be explained by stronger contributions from other processes (meridional mixing, chemistry) than the residual mean circulation.
Also I will explain theoretical background for calculations of mean meridional velocities.
Autumn Semester 2003
Tues. 2 September
Prof. Amos Zemel (Ben Gurion University of the
Negev, Israel), Innovative Renewable Energy
Research in Israel: From Large Scale to Small Scale
and Back. [Abstract]
11 September
Prof. Dr Ingrid Mann (Institut für
Planetologie, Westfälische
Wilhelms-Universität, Germany), The
Heliosphere and the Meteoritic Complex.
[Abstract]
18 September
Prof. Bengt Hultqvist (IRF-K), Downward
Accelerated Ions: Acceleration Mechanism and Ion
Source. [Abstract]
25 September
Prof. Rickard Lundin (IRF-K), Plasma in the
magnetospheric boundary layers: Frozen in - or not?
[Abstract]
2 October
Magnus Emanuelsson (IRF-K), Strålningstest
av OpAmpar. [Abstract]
Mon. 13 October, 10 am (Aula)
Dr Evgenia Belova (IRF-K), How and why we heat
the ionosphere. (Docent lecture)
16 October, 10-12 (Aula)
Spatial Modelling Centre (SMC), Umeå
University: Presentation of the database ASTRID,
the micro-simulation model SVERIGE, and related
projects. [Abstract]
23 October
Dr Mats Holmström (IRF-K), Monte Carlo
simulations of planetary ions and neutrals at
Mercury. [Abstract]
30 October
Grigory Nikulin (PhD student, IRF-K), Influence
of early winter wave activity on midwinter
circulation in the stratosphere and troposphere.
[Abstract]
6 November
Dr Yasuhide Hobara (postdoc, IRF-K), Extremely
low frequency radiation and ionospheric
disturbances in association with transient luminous
events in the mesosphere. [Abstract]
13 November
Dr Peter Dalin (IRF-K), The comparison of Danish
and Moscow NLC observations: statistical results.
[Abstract]
20 November
Dr Hans Nilsson (IRF-K), Radar Observations in
the Vicinity of Pre-noon Auroral Arcs.
[Abstract]
4 December (Aula)
Walter Allvin (Zero Group) presents Xero and the
Zero Group\'s activities (in the Aula): www.xero.se
11 December
Dr Tima Sergienko (IRF-K), The lateral spread of
proton precipitation: A comparison between
incoherent scatter radar observations and model.
[Abstract]
ABSTRACTS
Professor Amos Zemel (Ben
Gurion University of the Negev, Israel),
\"Innovative Renewable Energy Research in Israel:
From Large Scale to Small Scale and Back.\"
Renewable energy research carries a long
tradition in Israel. It is strongly
associated with the name of Dr. Harry Zvi
Tabor, the solar energy pioneer who, back in
the 50\'s, introduced and promoted the concepts
of selective coatings, the solar pond (based
on the idea originated by R. Bloch) and
participated in the development of the Organic
Rankine Cycle turbine. These concepts have now
turned classical, and evidence of solar energy
at
work is apparent on the rooftop of every
Israeli house by the obligatory domestic solar
hot water systems. While intensive R&D
efforts in Israel continue to advance nearly
every aspect of solar energy research, my aim here is to
present some of the most exciting approaches
that are being investigated. Not all of the
systems described here have reached the stage
of commercialization. Yet, if they stand up to
expectations, some may revolutionize the way
we think about solar energy and use it for the
benefit of mankind. In order to illustrate the wide scope and
diversity of these novel ideas, the systems
are classified according to their scales - from
very large dishes and central receivers
through mini-dishes to the molecular structure of
novel PV materials - and back to the
gigantic \"energy towers\" that involve the highest
structures ever built by human beings.
Prof. Dr Ingrid Mann (Institut
für Planetologie, Westfälische
Wilhelms-Universität, Germany), \"The
Heliosphere and the Meteoritic Complex.\"
The near-solar cloud inside Earth orbit
is the central region of the meteoritic complex
that evolves from the small bodies of our
planetary system. With its complexity of acting
forces, physical processes, and interactions, it
provides a unique opportunity for directly
studying a cosmic dust-plasma cloud and
processes therein that also appear in other
cosmic environments. Dust particles produce the
solar F-corona and the zodiacal light and
sun-grazing comets are observed falling into the
Sun. Yet, these astronomical phenomena reveal
only a part of the dust physics in the inner
solar system. Dust charging, surface reactions
and dust destruction are not accessible to
direct observations. The production of pick-up
ions provides the connection of the meteoritic
complex to other populations of heliospheric
particles. Recent observations from spacecraft
open up new possible scenarios as to the sources
and composition of meteoritic material in the
inner solar system.
Prof. Bengt Hultqvist
(IRF-K), \"Downward Accelerated Ions: Acceleration
Mechanism and Ion Source.\"
First, a summary of the observations of
downward accelerated ions with keV or sub-keV
energies at altitudes of about 1700 km is given
and the mechanism causing the accelerating
quasi-static potential difference is described.
Thereafter it is shown that the ionospheric ions
may be transported upward through the potential
region in a process sometimes called the
\'pressure-cooker\' mechanism involving wave
turbulence within the region. The turbulence
also gives rise to pitch-angle scattering of the
ions so that a fraction of them are precipitated
into the altitude range where they are observed
by the satellite. This process gives the
observed spectral characteristics of the
accelerated ions.
Prof. Rickard Lundin
(IRF-K), \"Plasma in the magnetospheric boundary
layers: Frozen in - or not?\"
The notion Frozen-in Magnetic
Field-Lines originates from Hannes
Alfvén, a result of a work on
electromagnetic-hydrodynamic waves published in
1942 that rendered Alfvén the Nobel prize
in Physics in 1971. Frozen.in magnetic field, or
ideal MHD, IM, has subsequently become widely
used in space plasma physics - misused according
to the inventor himself. The debate on the
applicability of IM started in the late 1950:ies
and has basically continued ever since. The
debate is not about the limitations of IM, these
are relatively well understood. Magnetic
reconnection, the \"fusing\" of magnetic field
lines, is an example of a microscopic process
where ideal MHD is locally violated. However, it
is then also assumed that the local violation
will not affect the macrostructure. IM is
assumed to hold on an overall basis regardless
of microphysical exceptions.
The issue is therefore to determine directly
from plasma measurements whether IM holds on a
large-scale basis - or not. One crucial aspect
is to test whether E = - vxB, i.e. the plasma
drift is determined by the electric field. Yet
another is to test whether the change in
magnetic flux (dB/dt) equals the rotation of vxB
(rot(vxB)). In this report I will present
Cluster CIS-data showing when IM applies and
when it does not. I will also give a study
report on a way to determine an IM-index from
space plasma data.
Magnus Emanuelsson (IRF-K),
\"Strålningstest av OpAmpar.\"
På seminariet avhandlades:
- Hur målsättningen
med resan var att öka IRF-K:s
kunskaper om stråltester i Uppsala,
och dessutom utvärdera både
mätmetoder och komponenter.
- Vilka resurser som finns att
tillgå hos IRF-U och The Svedberglaboratoriet i Uppsala.
- Vilka instrument, vilken
testmetod och vilken uppkoppling som
användes i stråltesten.
- Testresultat för
operationsförstärkarna LMC6484,
AD704, AD713.
- Vilka erfarenheter vi
fått av resan och testerna och hur
dessa kan förbättras.
- Vad mer vi vill testa
framöver.
Spatial
Modelling Centre, Umeå University,
\"Presentation of the database ASTRID, the
micro-simulation model SVERIGE, and related
projects.\"
After a short presentation of SMC, we
will inform you about our demographic database
ASTRID. This database is one of the most
important sources for all research performed at
SMC.
The main project, that more or less all the
other projects are connected to, is the
micro-simulation model SVERIGE. We can simulate
the lives of 10 million citizens in Sweden where
everyone on a yearly basis is exposed to the
possibility of various life events
happening.
The life events in SVERIGE are divided into
different modules. The modules that affect the
demography are fertility, mortality, emigration
and immigration. In addition there are modules
concerning family structures such as leaving
home, finding a partner and forming a new family
(cohabiting), marriage and divorce. In SVERIGE
everyone is educated to different degrees, they
can get a job and a salary. All these modules
are connected and they influence each other
dynamically. It is possible to simulate the life
of 10 million people in about one and a half
minutes per year.
We will also mention some other simulation
projects such as KINA, LISA and Transmission of
infections in Sweden.
To run such large models it is necessary to
develop techniques so that the computer can
handle all the agents and their variables in an
acceptable time. We will inform you of how we
handle this technically.
Lastly we will give you a short introduction
to subprojects such as Long-distance commuting,
Mortality related to weather situations and
climate, Mortality related to distance to care,
Tourism and regional development, Tourism in
protected national areas, and Employment, labour
market and regional development.
Dr Mats Holmström
(IRF-K), \"Monte Carlo simulations of planetary ions
and neutrals at Mercury.\"
Very low energy neutral atoms (VLENA)
at Mercury are produced at the surface by photon
stimulated desorption, micro meteoroid
vaporization, sputtering (from precipitating
neutrals and ions) and thermal release. Also,
charge-exchange is a source. The loss processes
are, surface precipitation, photoionization and
charge-exchange.
We have studied the production of photoions
at Mercury using a Monte Carlo model, and have
computed distribution functions and
precipitation maps for photoions produced from
several neutral species, such as O and Na. Using
the computed precipitation maps, the amount and
morphology of sputtered neutrals, due to
precipitating photoions, can be estimated. Among
other things, it is found that photoions can be
accelerated to high energies before impacting
the planetary surface, e.g., several keV for
oxygen.
Grigory Nikulin (PhD
student, IRF-K), \"Influence of early winter wave
activity on midwinter circulation in the
stratosphere and troposphere.\"
Using NCEP/NCAR reanalysis data we show
that the November-December averaged
stratospheric eddy heat flux is strongly
anticorrelated with the January-February
averaged eddy heat flux in the midlatitude
stratosphere and troposphere. This finding
further emphasizes differences between early and
midwinter stratospheric wave activity behavior,
which have recently been found in long-term
variations. Our analysis suggests that this
anticorrelation results from changes in wave
activity generation in the troposphere. Stronger
(weaker) wave activity in early winter leads to
weaker (stronger) wave activity generation in
the troposphere during midwinter. We show also
that enhanced equatorward wave refraction during
midwinter that is due to the stronger polar
night jet, is associated with weak wave activity
in the early winter. It is suggested that the
effect of enhanced midwinter wave activity
generation in the troposphere in the years with
weak early winter wave activity overcompensates
the effect of increased equatorward wave
refraction in midwinter, leading to a net
increase of the midwinter wave activity flux
into the stratosphere.
Trends are opposite in early- (positive) and
midwinter (negative) wave activity for the
1979-2002 period. However, the early winter
trends are at the edge of statistical
significance and very sensitive to the choice of
period in contrast to the midwinter trends.
Dr Yasuhide Hobara (postdoc,
IRF-K), \"Extremely low frequency radiation and
ionospheric disturbances in association with
transient luminous events in the mesosphere.\"
TLEs (transient luminous events) in the
mesosphere like red sprites and elves were
observed over the sea of Japan during the
thunderstorm activity in the wintertime. We
analyze quantitatively the results from
coordinated measurements consisting of ELF
(extremely low frequency) electromagnetic
radiation, VLF (very low frequency)
subionospheric disturbances, and lightning
discharges associated with these optical events.
We found a clear relationship between vertical
charge moment change calculated from ELF
observation and the ionospheric disturbances
regardless of the types of optical events. This
indicates significant
atmosphere-mesosphere-ionosphere coupling.
Sprites tend to associate with large ionospheric
disturbances (-13 to +4.6 dB) with a large
vertical charge moment change, whereas a large
lightning peak current (+223 to 479 kA) leading
to the strong EMP (electromagnetic pulse) is
necessary to initiate elves, but with rather
small ionospheric disturbances.
Dr Peter Dalin (IRF-K), The
comparison of Danish and Moscow NLC observations:
statistical results.
P. Dalin, S. Kirkwood, H.
Andersen, O. Hansen, V. Romejko
Systematic NLC observations conducted in
Denmark and Moscow during the period 1983-2002
are compared and statistical results both for
seasonally summarized NLC parameters and for
individual NLC appearances are described.
Careful attention is paid to the weather
conditions in each NLC case. This turns out to
be a very important point both for NLC case
study and for correlation analysis of average
values. Time series of seasonal values show
rather good similarity (taking into account the
weather conditions) but, at the same time, the
comparison of individual cases of NLC occurrence
reveals substantial differences.
Dr Hans Nilsson (IRF-K),
Radar Observations in the Vicinity of Pre-noon
Auroral Arcs.
A combination of EISCAT incoherent
scatter radar observations, FMI Longyearbyen
allsky camera observations, IMAGE magnetometer
chain data and Polar spacecraft data has been
used to study pre-noon dayside auroral arcs. The
studied arcs are mainly related to the shear
region between the morningside eastward flow
(the return flow region) and the shielded,
corotating plasma. These arcs thus appear on
closed field-lines, though they still show
mainly poleward motion similar to poleward
moving auroral forms. The EISCAT Svalbard radar
data allow us to study in some detail the plasma
in and surrounding the arcs and in particular
the morpholgy of the transverse electric field
associated with the arcs. It turns out that the
arcs are associated with a strong transverse
electric field on the poleward side, consistent
with post-midnight nightside observations. The
appearance of the arcs studied in detail is
associated with enhancements of the electric
field in the equatormost part of the eastward
flow region. Electric field and arc
intensifications occur on a 3-5 minute time
scale. The interchange instability is discussed
as a plausible source process for the arcs. The
source plasma population is studied using Polar
data. Polar electron data is also used as input
to a model, and the model results are compared
to the EISCAT and all-sky camera observations.
Agreement is found to be very good in the
diffuse aurora.
Dr Tima Sergienko
(IRF-K), The lateral spread of proton
precipitation: A comparison between incoherent
scatter radar observations and model.
Incoherent scatter radar (EISCAT)
observations of the quiet time evening sector
ionosphere show a very smooth equatorward border
of the region of enhanced ionization associated
with the diffuse auroral precipitation.
Conjugate satellite observations show that the
equatormost diffuse aurora typically consist of
proton precipitation only. Furthermore, a rather
sharp equatorward cut-off of the proton
precipitation is observed. The difference
between the radar and satellite measurements is
expected to be due to charge exchange spread of
the protons. A comparison between the satellite
and radar data thus allows for an unprecedented
observation study of the charge exchange
spreading effect. The satellite (DMSP) data are
used as input to a model of the electron and
proton transport into the atmosphere based on
Monte Carlo simulations. The agreement is found
to be very good.
Sven Bugarski (University of Heidelberg),
Methods and Problems of BrO DOAS Analysis.
[Abstract]
7 February
Mats André (IRF Uppsala), Layers at ion
and electron scales in the high-latitude
magnetopause.
11 February
Dr Takumi Abe and Dr Takeshi Imamura (Japan),
Japanese Venus Climate Orbiter.
13 February
Evgenia Belova (IRF-K), A Study of Polar
Mesosphere Summer/Winter Echoes with the EISCAT VHF
Radar. [Abstract]
20 February
Vladimir Safargaleev (Polar Geophysical
Institute, Apatity, Russia), High-latitude dayside
Pc1 events as indicator of reconnection.
[Abstract]
27 February
Rickard Lundin (IRF-K), The Wakes and
Magnetotails of Venus and Mars. [Abstract]
13 March
Grigory Nikulin (IRF-K), Dynamical contributions
to the total ozone trends in the Northern
Hemisphere midlatitude. [Abstract]
20 March, 1 p.m.
Sheila Kirkwood (IRF-K), Dust in the mesosphere
- is it really there and why should we care?
[Abstract]
27 March
Susanne Roslin (Umeå University),
Adsorbtion of CFC on Carboxen during sampling in
the stratosphere. [Abstract]
3 April
Peter Dalin (IRF-K), The observation of gravity
waves in Noctilucent Clouds. [Abstract]
10 April, 1 p.m.
Asta Pellinen-Wannberg (IRF-K), The EISCAT
meteor method: a review and recent results.
[Abstract]
Tues. 22 April, 10 a.m.
Hans Nilsson (IRF-K), Cluster multi-point
observations of ion outflow. [Abstract]
8 May
No seminar (Rymdforum 03 conference in
Kiruna)
15 May
Csilla Szasz and Johan Kero (IRF-K), A Solar
Active Region Quasi-Biennial Fluctuation.
[Abstract]
22 May
Sachiko Joko (IRF-K), Ion velocity distributions
at higher altitudes observed by CIS/Cluster:
Formation of shell-like distribution as observed in
cometary pick-up ions? [Abstract]
5 June
Jane Zheng-Johansson (IOFPR, Nyköping),
Unification Scheme for Classical and Quantum
Mechanics at All Velocities. [Abstract]
12 June
Herbert Gunell (IRF-K), Simulated ENA images of
the Venus-solar wind interaction region.
[Abstract]
19 June
Tima Sergienko (IRF-K), Quenching rates of O(1D)
in the upper thermosphere. [Abstract]
ABSTRACTS
\"Methods and problems of
BrO DOAS analysis\", Sven Bugarski (IRF-K)
The focus of the seminar will be the
DOAS (Differential Optical Absorption
Spectroscopy) measurements from the University
of Heidelberg at IRF. I will briefly describe
the involved instruments, explain the methods to
calculate SCDs (slant column densities) of trace
gases and discuss problems, results and aims of
my work.
\"A Study of Polar Mesosphere
Summer/Winter Echoes with the EISCAT VHF Radar\",
Evgenia Belova (IRF-K)
I will tell about use of EISCAT VHF
radar in studies of mesospheric layers which
occur in summer and winter time. My report is
based on the presentations given on the last
COSPAR conference in Houston, USA in October
2002. The abstracts of these presentations are
below:
STUDY OF POLAR MESOSPHERE WINTER ECHOES
DURING SOLAR PROTON EVENTS WITH THE EISCAT VHF
RADAR
E. Belova (1), S. Kirkwood (1), M. Rietveld
(2, 3), I. Häggström (3)
(1) Swedish Institute of Space Physics, Kiruna,
(2) EISCAT Scientific Association, Kiruna, (3)
Max-Planck-Institut für Aeronomie,
Katlenburg-Lindau
Recently, Kirkwood et al. (2002) reported
detecting enhanced MST radar echoes from
mesospheric altitudes in the winter period
during Solar Proton Events (SPEs). It was
proposed to refer to them as Polar Mesosphere
Winter Echoes (PMWE). They showed
characteristics from which one can conclude that
aerosols are most likely involved in generation
of the radar echoes, in the same way as for
PMSE. It was also found that there is no direct
dependence of PMWE occurrence on electron
density (calculated using ionospheric
modelling). However PMWE occurrence correlates
well with low values of l (the ratio of negative
ion density to electron density, derived also
from the model). Our aim is to check these
results by applying a new EISCAT D-layer program
during PMWE events. On November 5 and 23, 2001
two strong SPEs occurred. The ESRAD 52 MHz MST
radar detected enhanced backscatter from 65-75
km altitude. The EISCAT VHF radar was running
the D-layer Common Program. We use electron
density profiles derived from incoherent
backscattered power to interpolate electron
density at the PMWE altitudes. The relationship
we obtain between PMWE power and electron
density will be presented and discussed.
RELATION BETWEEN POLAR MESOSPHERE SUMMER ECHO
POWER AND ELECTRON DENSITY AS MEASURED WITH THE
EISCAT VHF RADAR
E.Belova (1), I. Häggström (2), P.
Chilson (3), S. Kirkwood (1)
(1) Swedish Institute of Space Physics, Kiruna,
(2) EISCAT Scientific Association, (3)
Cooperative Institute for Research in
Environmental Sciences, University of Colorado,
and NOAA Environmental Technology Laboratory,
Boulder
Strongly enhanced radar echoes from the polar
summer mesopause (PMSE) are an indicator of the
complex processes occurring in this important
region. They reflect coupling between neutral
and ionised atmospheric components, the latter
including electrons, ions and charged aerosols.
The dependence of PMSE power on background
electron density has been discussed in several
papers. Electron density values used for such
studies have been derived from model
simulations, or proxies such as riometer data
have been used to estimate electron density at
mesospheric altitudes. Reliable rocket
measurements of electron density are available
only for a small number of cases. They are not
sufficient to make a firm conclusion either on
the dependence of PMSE power on electron density
or on electron density limits for the existence
of these strong echoes. The latter may be
crucial for testing existing PMSE theories. We
propose to use a new D-layer EISCAT Common
Program (CP) for deriving electron density and
other ionospheric parameters just below and
above the layers with abnormally enhanced power.
Values of background electron density at
altitudes of PMSE can be calculated using
interpolation. In summer 2002 a PMSE experiment
will be conducted in Northern Norway using the
EISCAT VHF radar. It will be run in 2 modes: the
D-layer CP and Special Program (SP). The SP is
designed to detect and to measure PMSE power. By
running the D-layer program for 24 hours we
expect to cover a wide range of electron density
values. The first results of this experiment
will be presented. The relationship we obtain
between PMSE power and electron density will be
discussed.
\"High-latitude dayside
Pc1 events as indicator of reconnection\", Vladimir
Safargaleev (Polar Geophysical Institute, Apatity,
Russia)
The data of induction magnetometer
installed at Barentsburg observatory in
Spitsbergen archipelago are analyzed in combination with the data
of two other magnetometers located on
Scandinavian and Kola Peninsulas. We considered the
intervals of very large negative IMF Bz when
the cusp is assumed to be shifted at large distance south of
its statistical position and Spitsbergen
turns out in the polar cup.
Altogether, eight intervals were
considered. In all cases the DMSP data
indicated that Barentsburg observatory was in the polar cap, whereas
the location of two others might be
associated with either cusp or llbl or bps projections. The
magnetic pulsations of Pc1 frequency range
were observed around the local noon and in the polar cap only.
They had a form of several short-living
bursts and lasted for 5 - 15 minutes. In the cases when
the CUTLASS data were available, the interval
of Pc1 activity coincided well with the appearance and
decay of fast ionospheric convection flow
channel. We think that these pulsations are originated from
the magnetosheath (namely, from the plasma
depletion layer) where the plasma is anisotropic and
undergoes the IC-instability. Due to
impulsive reconnection, the unstable plasma turns out on the magnetic
field lines connected with the Earth\'s
ionosphere and IC-waves may be seen on the ground as the bursts
of Pc1.
\"The Wakes and Magnetotails
of Venus and Mars\", Rickard Lundin (IRF-K)
R. Lundin and S. Barabash
The solar wind interaction with the weakly
magnetized Venus and Mars differs from the solar
wind interaction with the Earth and other
strongly magnetized planets in our solar system.
A significant difference between magnetized and
unmagnetized planets is the stand-off distance
to the solar wind, the solar wind impacting
directly on the topside atmosphere of
nonmagnetized planets, whilst a strongly
magnetized planet fends off the solar wind well
above the atmosphere. In fact, neglecting the
difference in gravitational pull, there are many
similarities between Mars, Venus and comets in
terms of their interaction with the solar wind.
However, for the nightside tail region the
difference between magnetized and nonmagnetized
celestial objects are less marked. Nonmagnetized
celestial objects with an atmosphere have, like
magnetized objects a magnetotail induced by
their interaction with the solar wind.
In this report we review the magnetotails of
Mars and Venus and compare with the
observational/ visible characteristics of
comets. Besides their overall morphology and the
general atmospheric outflow/erosion, we also
consider the filamentation of ionospheric plasma
ejected into the magnetotail from non-magnetized
as well as magnetized bodies in the inner part
of the solar system.
\"Dynamical contributions to
the total ozone trends in the Northern Hemisphere
midlatitude\", Grigory Nikulin (IRF-K)
During last years more and more evidences
showing importance of
dynamic processes for the total ozone
decline have been presented. A
separation of chemical and dynamical
contributions to total ozone
variability is the significant question
for understanding of the ozone
changes. Several recent studies have
shown that a substantial part of
year to year winter-spring total ozone
variations in the Northern
Hemisphere (NH) middle and polar
latitudes are influenced by dynamic
factors. Wave activity in the lower
stratosphere and different indices
of atmospheric circulation patterns are
mostly used as dynamical
proxies. At the same time estimations of
dynamical contributions in
the observed long term ozone trends are
very different. Partly it
could be explained by different months
and periods that have been
taken for investigations.
The multiple linear regression model
describing evolution of the NH
midlatitude total ozone during
February-May (1979-2001) has been
applied to estimate contributions of
atmospheric circulation changes
to the observed long-term trends in total
ozone. We use 4 predictors,
namely: the 100 hPa zonal mean heat flux,
the Arctic Oscillation index,
the quasi-biennial oscillation and the
11-year solar cycle. The
regression accounts for 77% of the
observed total ozone variance in
May, 83% in April, 77% in March, and 76%
in February. There are no
significant trends in the model residuals
from March to May. The
February residual trend is on the edge of
statistical significance and
reduced by more than two times. The
obtained results show that the
dynamic factors can play the primary role
in the long-term changes of
the NH midlatitude total ozone.
\"Dust in the mesosphere -
is it really there and why should we care ?\" Sheila
Kirkwood (IRF-K)
There is a continual rain of
extraterrestrial matter into our atmosphere.
There are also increasing amounts of material
sent up from the Earth\'s surface (space debris,
rocket exhausts). There are theoretical grounds
for expecting that this leads to a population of
\'dust\' in the middle atmosphere, but this dust
has not yet been proven to exist. If it does
exist, it can have significant consequences for
atmospheric composition by introducing
heterogeneous chemical reactions. It is also of
importance for the interpretation of remote
sensing by optical methods - the usual
assumption is that there is no dust so that dust
layers will be interpreted as something else
(e.g. extremely low temperatures or high water
content).
In the last 3 years we have found radar
echoes with ESRAD and EISCAT which seem to
correspond to dust layers. The seminar will be a
progress report on how we are building up
evidence (using radar, lidar and rockets) that
these echoes cannot be explained by anything
else (such as turbulence).
\"Adsorbtion of CFC on
Carboxen during sampling in the stratosphere,\"
Susanne Roslin (Umeå University)
DESCARTES is a balloon-borne instrument
for the measurement of long-lived trace
gases in the stratosphere. The principle
behind the instrument is that by letting
a
measured amount of volume pass through
sample tubes containing the adsorbent
Carboxen, trace gases will be trapped
inside the sample tube while the rest is
passing
through. The instrument adsorb CFC-11,
CFC-113, CCl4 and CH3CCl3 in measurable
quantities but is optimised for
CFC-11.
The seminar will focus on the adsorption
efficiency of the sample tubes.
Preliminary
results of my study will be presented.
Can quantitative adsorption of primary
CFC-11
be secured during sampling with DESCARTES
in the stratosphere?
\"The observation of gravity
waves in Noctilucent Clouds.\" Peter Dalin
(IRF-K)
We have considered one case of
observation of gravity wave in the NLC observed
above Sweden. Visual observations supplement
substantially to radar measurements (Esrange and
Andenes) with the finding of small and
medium-scale of gravity waves and may be very
useful in the analysis of their dynamics even
the NLC being observed from one point. In the
examined case both optical and radar
observations revealed a gravity wave with
approximately the same characteristics
propagating from south-east to north-west
direction. This direction coincides with what
was found by Vincent and Fritts (1987) for
medium-period waves in summer season.
\"The EISCAT meteor method:
a review and recent results\", Asta
Pellinen-Wannberg (IRF-K)
The most important stages of
development of the High Power Large Aperture
(HPLA) radar method for meteor observations is
presented from the European Incoherent Scatter
(EISCAT) Facility point of view. The strength of
EISCAT for this application is its high
latitudinal location, dual frequency and
tristatic observation possibilities. Meteoroid
vector velocities can be derived from the
tristatic observations. At EISCAT they average
at about 65 km/s, which can be related to large
cross sections for collisional ionization in
hyperthermal collisions. Recent very high
resolution observations simultaneously from
three directions show processes occurring as
some meteoroids pass through the radar beam.
Finally, intensive shower meteor input during
2002 Leonids is related to ordinary ionospheric
incoherent scatter observations.
\"Cluster multi-point
observations of ion outflow\", Hans Nilsson
(IRF-K)
A case study of oxygen ion energization and
outflow is presented. The data
show oxygen ions being energized to energies
of up to 40 keV, the upper
energy limit for the CLUSTER CIS ion
spectrometer. The most important finding
is that the energization appear to be
isotropic at high altitude, in contrast
to lower altitude energization which is
typically transverse to the magnetic
field.
Furthermore the multi-spacecraft configuration
is used to analyze the observed
structures in detail. It is discussed what
we can expect to observe for
different situations, and this is compared
with actual observations. In
particluar a mesoscale event of strong
heating and associated outflow appears
to show a temporal decay which is similar
for the two observing spacecrafts.
This indicate that both spacecrafts were
situated in a coherent region where
all field-lines had a similar history, as
could for example be expected in
the flux bundle expected from a flux
transfer event.
\"A Solar Active Region
Quasi-Biennial Fluctuation\", Csilla Szasz and Johan
Kero (IRF-K)
A quasi-biennial fluctuation has been
detected in the time-series of the sunspot
umbra/penumbra area ratio (U/P) on the basis of
the Debrecen Photoheliographic Data. The study
is based on an intermittent period of nearly
eight years; the material comprises more than
18.000 individual sunspots.
In the seminar we will present information
about the temporal behaviour of the U/P ratio,
period analysis and umbral area dependence. The
physical background of the phenomenon is yet
unclear but it seems to belong to the growing
family of mid-term fluctuations.
\"Ion velocity distributions at
higher altitudes observed by CIS/Cluster: Formation
of shell-like distribution as observed in cometary
pick-up ions?\" Sachiko Joko (IRF-K)
During the years of 1986 and 1987,
after exploring comet Giacobini-Zinner and comet
Halley, a lot of observations and theoretical
studies by means of computer simulation on
cometary newborn \'pick-up\' ions and their
behaviours have been reported. Cometary newborn
ions picked up by the solar wind are known to
form shell-like configuration in velocity phase
space at ralatively far upstream of the nuclei
of comets, in which particle density is small
enough to be collisionless and so that linear
theory of electro-magnetic instabilities is
considered to be applicable. By means of
observations by the CIS instrument onboard the
Cluster satellite, at the dayside magnetosphere,
supposed to be in the poleward cusp or the
mantle region with above 8 Re (Earth radii) in
altitude, shell-like configuration in velocity
distribution of O+ ions has been found (We
believe so at this moment). In this seminar,
I\'ll just present how the shell-like velocity
distribution looks like and how related
electro-static and electromagnetic data seem to
be as the first stage of this study.
\"Unification Scheme for
Classical and Quantum Mechanics at All Velocities\",
Jane Zheng-Johansson (IOFPR, Nyköping)
I first review the whereabouts,
especially the unsolved problems in my opinion,
in the issues of physics relevant to here,
including the interpretation of
Schrötdinger\'s wave function, the nature of
inertial mass, space and time, the picture of
elementary particles in qft and in string
theory, and the unification schemes, etc.
I then introduce our recently achieved
result, The Unification of Classical and Quantum
Mechanics. Our approach is to firstly derive a
realistic submicroscopic model for vacuum (of a
Dirac kind) based on overall experimental
observations, establish Newtonian equation of
motion of it under external perturbation, and
solve. The solution and predictions are
presented in two parts. (I) The fundamental
formation of martial particles: Our solution
shows that, a basic particle, which may be e.g.
an electron, is composed of a tiny free
aether-pole (a bare charge) and the mechanical
wave disturbancesidentifying with
electromagnetic wavesgenerated by it in the
medium. When in motion, of velocity v (here
(v/c)-->0), as a result of a first kind
source effect this particle wave exhibits all of
wave and dynamic properties known for a de
Broglie wave, and is here called a Newton- de
Broglie (NdB) particle wave. In a confined
space, the Newtonian solution for the NdB
particle wave is equivalent to that given by
Schrödinger\'s quantum mechanics. Through
this general scheme for particle formation we
have accomplished a basic task of the
unification of classical- and the quantum-
mechanics, both in terms of the deduction of the
latter from the former, and the convergence of
the latter into the former at high velocities.
And we unfold the origins of a series of
phenomena including the electromagnetic waves,
the electromagnetic radiation and absorption,
atomic and thermal excitations, the inertial
mass, the Schrödinger\'s wavefunction and de
Broglie wave, the Heisenberg\'s uncertainty
relation, the de Broglie relations, the
simultaneous existence of electron and positron
or generally of particles and their
anti-particles, the (rest) mass-energy
equivalence relation, etc. (II) The Theory of
Relative motion: (A) we show that the
(v/c)^2-dependent terms yield in the particle
wave and dynamic quantities a second kind source
motion effect (SSME). The SSME augments the
particle mass, and the wavevector and frequency
of the particle\'s constituent waves, etc., by a
factor \\g = 1/\\sqrt{1-v^2/c^2} in the
v-direction; and conversely for the reciprocal
quantities. Subsequently a moving body
comprising the so affected particles will
present a simultaneous length and time
contractions (of Lorentz-Fitzgerald kind) as
measured in the frame attached to the body. (B)
A systematic survey of pivotal experimental
indications leads us to conclude that the light
velocities, c measured in vacuum and c\' measured
by a moving observer, and the observer\'s v obey
the common triangle law of vector addition,
conforming to the Galilean transformation (GT).
(C) Combining (A) and (B) yields a set of
transformation equations between an inertial
reference frame at rest (in vacuum) and one
moving relative to it, called Galilean-Lorentz
transformation (GLT). The GLT together with the
underlying theoretical basis of the general
scheme yields a consistent Theory of Relative
Motion. With the theory, we predict the
observational null-/constant- fringe shift
result of the Michelson-Morley/Kennedy-Thorndike
experiment, the Doppler effects of
electromagnetic waves, the equivalence principle
of Newton\'s laws of motion in all inertial
frames, etc, and we extend the classical and
quantum mechanics to (v/c)^2 >>0. The
complete agreement is in turn a justification of
the general scheme.
Finally, I outline the on-going and planned
research problems within our unification
projects, these including the derivation of
Schrödinger\'s equations from Newton
mechanics, the formulations of a microscopic
theory of gravity, and a theory of relative
motion in non-inertial frames, and a treaty of
cosmological problems.
\"Simulated ENA images of the
Venus-solar wind interaction region\", Herbert
Gunell (IRF-K)
We present simulated images of
energetic neutral atoms (ENAs) produced in
charge exchange collisions between solar wind
protons and neutral atoms in the exosphere of
Venus.
The ENA images are generated through the
integration of the ENA production along lines of
sight to a virtual ENA instrument. A model, that
is based on measurements, of the neutral gas
density in Venus\' upper atmosphere is used in
combination with a model of the plasma flow
around Venus. The plasma model is a
semi-analytical MHD model developed by Helfried
Biernat and Nikolai Erkaev.
The images are found to be dominated by two
local maxima. One produced by charge exchange
collisions in the solar wind, upstream of the
bow shock, and the other close to the dayside
ionopause. The simulated ENA fluxes at Venus are
lower than those obtained in similar simulations
of ENA images at Mars.
\"Quenching rates of O(1D) in
the upper thermosphere\", Tima Sergienko
(IRF-K)
The 6300Å (red line)
originated from the metastable O(1D) state is
extensively used in the optical remote sensing
of the upper atmosphere. The radiative lifetime
of the 1D sate is rather long (~110 sec) and
collision quenching by atmospheric gases is
significant loss process for this state.
Therefore the quenching rate coefficients are
crucial in determining the 6300Å emission.
While rate coefficients for quenching by N2
obtained in laboratory measurements and deduced
from aeronomical observations are in good
agreement, the importance of quenching by atomic
oxygen is still under debate. Multipoint Auroral
Large Imaging System (ALIS) measurements of
enhanced 6300Å airglow caused by HF
pumping in the ionosphere from the
EISCAT-Heating facility were used to determine
the effective lifetime of O(1D) state in
altitude range of 200-300 km. The quenching rate
coefficients obtained from the altitude
dependence of the O(1D) lifetime are discussed.
Autumn Semester 2002
3 October
Carl-Fredrik Enell (IRF-K), Optical Studies of
Stratospheric Clouds. [Abstract]
17 October
Narayana Rao (IRF-K), UTLS Ozone Variations
over Northern Europe. [Abstract]
24 October
Johan Arvelius (IRF-K), The Problem of
Identifying Tropopause Folds in Ozone Soundings
Avoiding Seasonal Biases. [Abstract]
14 November
Peter Dalin (IRF-K), An Estimation of
Inertio-Gravity Wave Parameters in Noctilucent
Clouds. [Abstract]
21 November
Sachiko Joko (IRF-K), Ionospheric Ions
Outflowing at High Altitudes in the Dayside
Magnetosphere. [Abstract]
Tuesday 26 November
Rickard Lundin (IRF-K), Ponderomotive Forces in
the Magnetosphere. [Abstract]
5 December
Herbert Gunell (IRF-K), Beam-Plasma Interaction.
[Abstract]
12 December (10-10.30)
Professor Liu (Center for Space Science and
Applied Research, China), A Brief Introduction to
the Chinese Double Star Project.
12 December (10.30-11)
Dr Li (Center for Space Science and Applied
Research, China), The Plasma Sheet Oscillation and
Compressional Pc5 Pulsations in the
Magnetotail.
12 December (11-11.30)
Pontus C:son Brandt (Applied Physics Laboratory,
USA), Usefulness of ENA Imaging for Magnetospheric
Research: New IMAGE Results.
19 December
Khaled Fadel (IRF-K)
Friday 20 December
Gösta Gahm (Dept of Astronomy, Stockholm
University), The Architecture of Interstellar
Clouds.
ABSTRACTS
Optical Studies of
Stratospheric Clouds, Carl-Fredrik Enell
(IRF-K)
This seminar is a short summary of the methods
used and developed in my PhD thesis, \"Optical
studies of polar stratospheric clouds and related
phenomena\". The principles of zenith-sky scattering
and the use of bistatic imaging will be discussed
and a few of the results discussed. It is shown
that PSC presence can be detected, but probably
underestimated, with zenith-looking photometers. A
case study of PSCs by bistatic imaging shows
changes on very short temporal and spatial
scales.
UTLS Ozone Variations
over Northern Europe, Narayana Rao
(IRF-K)
There has been growing interest in the upper
troposphere and lower stratosphere (UTLS) region in
the atmospheric scientific community over the past
few years for various reasons. They include
concerns about increase in emissions, in particular
NOx, from subsonic and supersonic aircrafts, which
normally fly in this region and variations of ozone
trends with height as well as spatial variations.
Different 3-D global chemistry and transport models
have estimated a NOx perturbation of 20-70% in the
8-12 km layer, causing an increase in O3
concentration by 2-9% through photochemical
reactions. Observed trends in ozone shows
interesting features with large decreases in the
lower stratosphere at high and mid latitudes in
both hemispheres, while the trends in the
troposphere shows regional differences with a
positive trend over Europe, a negative trend over
Canada and no statistically significant trend over
North America. However, most of the results on
trends and seasonal variation of ozone are based on
the data collected at mid-latitudes and Canadian
Arctic stations. There are no reported reliable
long-term measurement series of ozone in the
European Arctic mainly because of the paucity of
the long-term measurements of ozone. Most of our
understanding on European Arctic ozone is based on
results from a series of large campaigns, for
instance EASOE, SESAME, THESEO, SOLVE, conducted in
the European Arctic augmented by some other small
campaigns. So in this talk, I will discuss about
variations of ozone (annual as well as interannual)
over northern Europe using a relatively long-term
database of 7 years. I would also like to discuss
the relation between ozone and potential vorticity.
Further, I will present preliminary results on
the climatology of tropopause folds at high
latitudes.
The Problem of Identifying
Tropopause Folds in Ozone Soundings Avoiding
Seasonal Biases, Johan Arvelius (IRF-K)
A discussion forum on the easily-explained
problem of looking for tropopause folds in ozone
soundings avoiding seasonal biases. Hopefully the
discussion will concern the problem of looking for
similar structures in data with variable
structure.
An Estimation of
Inertio-Gravity Wave Parameters in Noctilucent
Clouds, Peter Dalin (IRF-K)
The case study of the Noctilucent Cloud (NLC)
appearance on August 10-11, 2000 is examined. The
clear wave dynamics are observed and the
inertio-gravity wave is supposed to be responsible
for the observed modulation in the NLC field. With
the Esrange MST Radar data and Andøya MF
Radar data we have managed to find the
inertio-gravity waves which propagate upward from
the stratosphere to the NLC altitude and could be
responsible for observed wave dynamics in the
NLC.
Ionospheric ions outflowing at
high altitudes in the dayside magnetosphere,
Sachiko Joko (IRF-K)
At the last spring EGS assembly I presented a
case study of the ionospheric ions, especially O+
ions in this case, outflowing at high altitudes
(higher than 6 Re) in the dayside magnetosphere
observed by CIS/Cluster. I have continued to study
this case and in this seminar I present several
additional issues including other cases. The case
of \"12 April, 2001\" shows that O+ ions were
continously accelerated/energized during the whole
orbit from the duskside polar cap, the cusp and the
magnetopause to the magnetosheath. But the
acceleration/energization processes differed
depending on the altitude. As for ion species
differencies, O+ and H+ behaved in different ways,
by which I mean that the influence of the
acceleration/energization processes on each ion
species seem to be different. In this seminar, if
we have enough time left, Hans Nilsson will give a
short talk on issues relevant to mine, based on his
presentation at the last COSPAR congress.
Ponderomotive Forces in the
Magnetosphere, Rickard Lundin (IRF-K)
We review the current state of the art in the
study of ponderomotive forces caused by ULF
electromagnetic waves in the terrestrial
magnetosphere. This field of research has attracted
considerable attention in recent years. Even though
the literature on the subject is quite extensive,
there are still challenging questions encountered
in applying the concept of ponderomotive forces to
analysis of concrete space phenomena. The review
presents a brief but clear and rational account of
the subject from the basics up to problems of
interest to research workers in the field of space
physics. The hydrodynamic, quasi-hydrodynamic and
test-particle approaches are used for description
of ponderomotive acceleration and redistribution of
ions in the ionosphere-magnetosphere coupled
system. Theoretical problems of the ponderomotive
wave-particle interaction are discussed in the
light of recent satellite investigations of the
auroral acceleration processes. We conclude that
the ponderomotive forces play an important role in
the structures and dynamics of the
magnetosphere.
Beam-Plasma Interaction,
Herbert Gunell (IRF-K)
This seminar concerns the interaction
between an electron beam and a
plasma. Laboratory experiments were
conducted using two different
setups; one with an electric double layer
and the other with a hot
cathode as the electron beam source.
In both experiments the it was found that
the electrostatic waves
generated by the beam-plasma interaction can
concentrate to a narrow
spike with a full width at half maximum that
is on the order of one
wavelength.
The narrow electric field spike has been
reproduced in a one-dimensional
electrostatic particle in cell simulation.
The spike is formed
only when the interaction occurs in the
plasma density gradient that
surrounds a double layer and exists in front
of a hot cathode. The
electron beam is spread in velocity space as
it passes the spike.
Based on a simplified fluid descriptions of
eigenmodes of a plasma
diode with a density gradient the
localisation of the spike, spatially
and in frequency, can be explained. The
conclusion, that is proposed
here, is that the spike can be seen as a
coupled system of two such
eigenmodes that receive their energy from
the beam-plasma interaction.
Spring Semester 2002
4 February
\"Kan man höra norrskenet? Den
naturvetenskapliga bakgrunden till ljudfenomen i
samband med starka norrsken\". Seminar by Christer
Jurén, IRF Kiruna.
14 March
\"Observations and Analysis of Artificial
Aurora\". Seminar by Björn Gustavsson, National
Institute of Polar Research, Tokyo, Japan.
21 March
\"Case Studies of the Dynamical Development of
Polar Stratospheric Clouds Using Multistatic
Imaging\". Seminar by Carl-Fredrik Enell, IRF
Kiruna. [Abstract]
28 March
\"Locations of proton isotropic boundaries as
measured by conjugate high-altitude and
low-altitude satellites\". Seminar by Natalie
Ganushkina, FMI. [Abstract]
9 April
\"Substorm results from Interball\" and a report
from the substorm conference in Seattle by Ingrid
Sandahl, IRF Kiruna.
11 April
\"Cluster high-altitude observations of
ionospheric plasma outflow\". Seminar by Sachiko
Joko, IRF Kiruna [Abstract]
18 April
\"Response of Polar Mesosphere Summer Echoes to
Ionospheric Heating\". Seminar by Evgenia Belova,
IRF Kiruna. [Abstract]
2 May
\"Trends in Moscow NLCs occurrence and
brightness.\" Seminar by Petr Dalin, IRF Kiruna.
[Abstract]
16 May
\"Aerosols, clouds and climate.\" Seminar by Johan
Arvelius, IRF Kiruna. [Abstract]
21 May
\"Longtime DOAS observation of trace gases in
Kiruna.\" Seminar by Thomas Wagner, Heidelberg,
Germany.
30 May
\"Auroral radiation of Jupiter.\" Seminar by Anil
Bhardwaj, Space Physics Laboratory, Vikram Sarabhai
Space Centre, India.
31 May
\"Space Program of India.\" Seminar by Anil
Bhardwaj, Space Physics Laboratory, Vikram Sarabhai
Space Centre, India.
4 June
\"Fast volume rendering.\" Seminar by Mats
Holmström, IRF Kiruna. [Abstract]
NB: in the Aula.
7 June, 1.30 p.m.
\"Waves and Fluctuations in Non-Maxwellian
Plasmas.\" Seminar by Herbert Gunell, Dept. of
Physics and Astronomy, University of Iowa.
[Abstract] NB: in the
Aula.
ABSTRACTS
\"Case Studies of the
Dynamical Development of Polar Stratospheric Clouds
Using Multistatic Imaging\". Seminar by Carl-Fredrik
Enell, IRF Kiruna.
The important role of polar stratospheric
clouds (PSCs) in
stratospheric chemistry is firmly
established. The formation of PSCs
is closely related to temperature, which is
affected by wave activity
on different scales. PSC occurrence thus
reflects radiative and/or
dynamical stratospheric temperature
changes.
The most obvious indication of PSC presence
is the visual observation
of mother-of-pearl clouds. We present case
studies of the development
of visual PSCs undertaken by means of
ground-based cameras. Our
observations show that the presence of
mother-of-pearl clouds varies
on a scale smaller than that of typical
mesoscale models.
The images are studied further in the
context of the meteorological,
dynamical situation, and visibility
conditions (solar elevation and
tropospheric cloudiness).
\"Locations of proton
isotropic boundaries as measured by conjugate
high-altitude and low-altitude satellites\". Seminar
by Natalie Ganushkina, FMI.
Polar CAMMICE MICS data of proton pitch
angle distributions with energies
of 31-80 keV for the period of 1997-1998
were analyzed to determine the locations
where
anisotropic pitch angle distributions
(perpendicular flux dominating) change to
isotropic
distributions. We study this high-altitude
isotropic distribution boundary
(IDB) in terms of its location in L-shell
and MLT. Statistical results
showed that this boundary is located at
lower L-shells on the nightside and
at higher L-shells on the dayside with most
distant location at dawn. With
the increase of magnetic activity, the IDB
positions shift towards lower
L-shells at all MLT. The locations of IDBs
were also determined for
different storm phases. A superposed epoch
analysis revealed that the
L-shells of the IDBs move to lower L-shells
with decreasing Dst and to
higher L-shells during Dst recovery. Several
events were selected during
which simultaneous observations in the same
local time sector were
available from Polar at high altitudes and
from DMSP at low altitudes. The
magnetic field mappings to find the relative
locations of both spacecraft
were made using the Tsyganenko T01 model
with the observed solar wind input
parameters. The mappings showed that Polar
and DMSP were placed on nearly
the same field lines, which leads us to
suggest that the Polar IDB and the
b2i boundary at DMSP are closely related,
and that the mapping between high
and low altitudes can be made sufficiently
accurately.
\"Cluster high-altitude
observations of ionospheric plasma outflow\".
Seminar by Sachiko Joko, IRF Kiruna.
With respect to ionospheric-origin O+ ions
upflowing through the polar cap, cusp/cleft or
mantle, and magneto-
sheath, observed by Cluster/CIS above 3-Re
altitude, increase of parallel flow velocity
seems to be fed
by increase of transverse energy, as shown
also by the previous study of Lundin and
Hultqvist (1989), but on the other hand,
parallel flow velocity continues to increase by
some other processes, like pressure gradient or
inertial drift.
\"Response of Polar
Mesosphere Summer Echoes to Ionospheric Heating\".
Seminar by Evgenia Belova, IRF Kiruna.
Polar mesosphere summer echoes (PMSE) are
abnormally strong radar returns
that occur during summer months near the
mesopause at high latitudes. They
were discovered about 20 years ago. It seems
that PMSE reflect complicated
processes occurring in a multi-component
plasma consisting of electrons,
ions and charged aerosols, and so far there
is no clear understanding of
the mechanism of PMSE. In order to influence
the electron component during
PMSE events, we conducted, in summer 1999, a
joint PMSE/Heating experiment
using the EISCAT VHF radar and the EISCAT
Heating facility. During our
experiment we demonstrated that PMSE was
indeed affected by the heating
pulses, with the back-scattered signal
decreasing when the heater was on.
The response time was less than 2 seconds.
(Chilson et al., 2000). We have
now analysed the backscattered powers for
selected time intervals and
heights for different PMSE/heating
experiments with the highest available
time resolution of 29.85 ms. We find that
there is an upper limit for the
time which it takes for PMSE power to
respond to switching the heater on or
off which is less than 30 ms. Such a rapid
response of the PMSE allows us
to differentiate between mechanisms which
could be responsible for the
heating effect on PMSE. We find that
enhancment of electron diffusivity
during heating is unlikely to be able to
account for so rapid a decrease of
radar backscattered power when the heater
switches on. We suggest that
increase of the Debye length up to half a
radar wavelength due to electron
heating in a presence of aerosols might
explain the heating effect on PMSE.
The time constant for this process is
expected to be in the 1 ms range.
Finally, we make a proposal for the next
PMSE/heating experiment which is
planed to conduct in summer 2002.
\"Trends in Moscow NLCs
occurrence and brightness.\" Seminar by Petr Dalin,
IRF Kiruna.
NLCs near Moscow, Russia are observing in
specially organized campaigns
every summer season from 1962 up to present
time. During this period all
the observers have been following the same
procedure of NLC registration
and accompanying comments, elaborated in
1962.
Some statistical results were obtained from
the database. One of its
important advantages is an accurate
accompanying meteorological information. It
allowed to
separate the cases of NLC no-registration
due to a break in observation or
due to a bad weather from the cases of real
absence during a clear night.
Such separation proved to be substantial for
obtaining of geophysical
significant statistical results for NLC
parameters. Long-term behaviour of
seasonally averaged NLC parameters was
studied. Most interesting results of
this investigation are decadal (about 10
years) variability, zero trend in
a NLC occurrence probability for a clear
night and a positive trend in
seasonally accumulated NLCs brightness
(normalized by the number of clear
nights). The difference between this result
and well-known result of
M.Gadsden (1990) is discussed.
\"Aerosols, clouds and
climate.\" Seminar by Johan Arvelius, IRF
Kiruna.
I will present some of the contents from the
course \"Aerosols, clouds and climate\" that
I
participated in this winter. The contents
was (luckily) not as broad as the
title indicated. It was rather about the
climatic effects of antropogenic
aerosols both directly and indirectly from
their impact on the cloud
formation processes. This large perspecive
will be discussed as well as
the modifications to the Köhler theory
of partly soluable aerosols and
gases as well as surfactants.
\"Fast volume rendering.\"
Seminar by Mats Holmström, IRF Kiruna.
It is difficult to interpret observed
energetic neutral atom (ENA)
images, since an image only depends
indirectly on the quantities that
usually are of interest - the distribution
of ions and neutrals.
For a detailed, quantitative, analysis of
observed images one can use
inversion techniques to extract parameters
from a mathematical model
of the ENA production. Basically, we
generate images until we find
one that closely match the observed image.
The parameters that
produce the best match is our parameter
estimate. The sequence of
generated images is determined by the chosen
minimization algorithm.
Thus, to solve the inverse problem,
hundreds, or even thousands, of
images must be generated and it is crucial
that we can generate each
image as fast as possible.
Computer imaging of volume emissions is a
general problem, of which
ENA imaging is just a special case. In
computer graphics this process
is denoted volume rendering. We have
developed an hierarchical,
wavelet based, method for fast imaging of
volume emissions. The
proposed method also provides error
estimates and error control,
automatically. The approach is to find a
sparse representation of the
volume emission, a three-dimensional
function, before the projection
onto the image plane. The representation is
based on conservative
subdivision. Numerical experiments suggest
that the proposed method
can be orders of magnitude faster than
traditional line of sight
integration, for similar errors in the
generated images.
\"Waves and Fluctuations in
Non-Maxwellian Plasmas.\" Seminar by Herbert Gunell,
Dept. of Physics and Astronomy, University of
Iowa.
A simple pole expansion can be used to model
the distribution function for
the purpose of calculating dispersion
relations for electron waves
(Lfgren and Gunell, Phys. Plasmas, vol. 4,
pp.3469-3476, 1997) and
ion-acoustic-like waves (Gunell and Skiff,
Phys. Plasmas vol. 8, pp. 3550-3557, 2001).
The
expansion is a rational function of the
complex phase velocity, and the
integration along the real axis is reduced
to a sum of the residues at the
poles of the expansion of the distribution
function.
For waves on the ion acoustic time scale we
find that slow weakly damped
modes exist in two-temperature plasmas, and
in plasmas with beam-like
tails, i.e. plasmas where the ion
distribution consists of two components
centred at different velocity. These slow,
weakly damped, acoustic-like
modes exist also when the tail component
constitutes a small fraction of
the total ion density. These weakly damped
modes have been observed in
laboratory experiments (Skiff, De
Souza-Machado, Noonan, Case, and Good,
Phys. Rev. Letters, vol. 81, p. 5829, 1998).
For plasmas with equal ion
and electron temperatures weakly damped
modes are found when there is a
depletion of the high energy tails. Weakly
damped modes are also found in
plasmas with equal ion and electron
temperatures in the presence of a low
density cold ion component.
Electrostatic fluctuations appear in stable
plasmas due to the
discreteness of the plasma particles. The
calculation of the spectral
density of these fluctuations in an
isotropic three-dimensional plasma
through superposition of the electric fields
of dressed test particles is
described in textbooks (e. g. Krall and
Trivelpiece, Principles of Plasma
Physics. New York: McGraw-Hill, 1973). The
test particle method has been
used to calculate the spectral density for
electrostatic fluctuations in a
plasma where the particles follow a kappa
distribution (Mace, Hellberg,
and Treumann, J. Plasma Physics, vol. 59,
pp.393-416, 1998).
Here we show how the electrostatic
fluctuations can be calculated for in
plasmas where both the ion and electron
distributions are described by
simple pole expansions, in 1D and isotropic
3D plasmas. We present
calculations of the spectral density of the
fluctuations as a function of
frequency and wavenumber. For comparison
with measurements we integrate
over wave number to obtain the spectral
density as a function of
frequency only.
Autumn Semester 2001
23 August
Evidence for impulsive solar wind plasma
penetration through the dayside magnetopause,
Rickard Lundin, IRF [Abstract]
30 August
Recent Cluster CIS (Cluster Ion Spectrometry)
results, Rickard Lundin, IRF
11 September
Comment on V.M.Vasyliunas, \"Electric field and
plasma flow: What drives what\". Seminar by M.
Yamauchi, IRF [Abstract]
23 October
The Use of Stratosperic
Tracer-Interrelationships to study chemical
reactions in the Spring Polar Vortex. Seminar by
Johan Arvelius, IRF [Abstract]
30 October
First results from RAPID on Cluster. Seminar by
Ingrid Sandahl, IRF [Abstract]
1 November
Analysis Technique School for Space Plasma Data.
Seminar by Sachiko Joko [Abstract]
6 November
Fast neutral atom imaging: A journey to Mars,
Mercury, and back. Seminar by Mats Holmström
[Abstract]
15 November
The Munin Plasma Data. Seminar by Kan Ogawa
[Abstract]
20 November
Framtiden för IRF:s jonosonderingar med
anledning av ett nytt anslag på 890 tkr
från Kempestiftelserna. Seminar by Christer
Jurén [Abstract]
NB: Seminar to be held in the Auditorium
(Aulan)
27 November
Fine structure of the diffuse auroral zone
observed simultaneously by ALIS and the FAST
satellite. Seminar by Tima Sergienko.
29 November
Cosmic Dust Measurements with HPLA radars.
Seminar by Asta Pellinen-Wannberg.
4 December
Are there clouds in the winter mesosphere?
Seminar by Sheila Kirkwood. [Abstract]
11 December
En kamera är väl en kamera? Ett
seminarium om äpplen och päron. Seminar
by Urban Brändström [Abstract]
ABSTRACTS
Evidence for impulsive solar wind
plasma penetration through the dayside magnetopause, Rickard
Lundin, IRF Kiruna.
This seminar will present in-situ observational evidence
from the Cluster Ion Spectrometer, CIS, on Cluster of
injected solar wind \"plasma clouds\" protruding the dayside
high-latitude magnetopause. The plasma clouds, presumably
injected by a transient process through the dayside
magnetopause, show characteristics implying a generation
mechanism denoted impulsive penetration (Lemaire and Roth,
1977). The injected plasma clouds, here termed \"plasma
transfer events\", PTEs (Woch and Lundin, 1991), are temporal
in nature and relatively limited in size. They are initially
moving inward with a high velocity, and a magnetic signature
that makes them essentially indistinguishable from regular
magnetosheath encounters. However, well inside the
magnetosphere PTEs are more easily distinguished from
magnetopause encounters. The PTEs may still be moving while
embedded in an isotropic background of energetic trapped
particles. Well inside the magnetosphere they expand along
magnetic field lines. However they frequently also have a
significant transverse drift component. The drift is
localised, thus constituting an excess momentum/motional emf
generating electric fields and currents. The induced emf
also acts locally, accelerating a pre-existing cold plasma
(e.g. Sauvaud et al, 2001). Observations of PTEs-signatures
range from \"active\" (strong transverse flow, magnetic
turbulence, electric current, local plasma acceleration) to
\"evanescent\" (weak flow, weak current signature).
Comment on \"Electric field and plasma
flow: What drives what\" by V.M. Vasyliunas, GRL, Vol 28, No,
11, June 2001. Seminar by M. Yamauchi, IRF Kiruna.
Vasyluinas recently revisited the cause-effect
problem of ExB drift and
polarization (VxB) electric field in
magnetohydrodynamics (MHD)
[Vasyluinas, 2001]. He substantially proposed
two critical things: (1)
inclusion of displacement current instead of
conduction current in Ampere\'s
law; (2) Viewing cause-effect relation as the initial
value problem. With
straight forward mathematical formulation under given
assumptions, initial
condition, Ohm\'s law, and boundary condition, he
showed that in 3-D free
space a given convection with finite linear initial
momentum causes
electric field which altogether keep the momentum
whereas a given
distribution of electric charge does not generate
substantial linear
momentum but only a mere oscillation. This is a
beautiful formulation of
plasma oscillation in MHD regime.
However, his lacks two important things:
(1) He did not include source terms (or boundary
condition) in his
formulation and he ignored non-uniform condiiton. As
a result the
formulation is not applicable to the large-scale
space phenomena although
the formulation is correct.
(2) He completely forgot the original causality of
MHD equations. While
mass conservation law is not cause-effect relation,
the momentum equation
and the induction equations are causality equations
which we need special
care. Then we have \"time scale of frizen-in
condition\" concept, which is
important for Solar wind plasma enter to the
magnetosphere without pilling
up the magnetic field.
The Use of Stratosperic
Tracer-Interrelationships to study chemical reactions in
the Spring Polar Vortex. Seminar by Johan Arvelius, IRF
Kiruna
A refresher of the idea of Stratospheric Tracers and
their
interrelationships that I\'ve given a couple of
seminars on earlier.
Thereafter there will be a presentation of some
resent studies that use
these to quantify chlorine and bromine activation and
the following ozone
depletion in the northern polar stratosphere during
the SOLVE/THESEO 2000
campaign winter 1999/2000.
First results from RAPID on
Cluster. Seminar by Ingrid Sandahl, IRF Kiruna
RAPID, the high energy particle instrument on
Cluster, measures electrons
in the energy range 20-400 keV and ions from 30 to
1500 keV. There is also
an ENA mode. There have been a number of initial
operation problems and
some sensor heads have suffered degradation of
sensitivity, but the RAPID
instruments on all spacecraft are now giving
scientifically useful data. In
this seminar the RAPID instrument will be described
and initial results
will be presented. I will also discuss the
capabilities as well as problems
of the instrument.
A report on the meeting in La
Londe les Maures in October on Analysis Methods for
Multi-Spacecraft Data. Seminar by Sachiko Joko, IRF
Kiruna
Sachiko will talk about:
Analysis Technique School for Space Plasma Data
- not on contents in detail but useful information
for you
This school (course) aims to get and exchange
advanced analysis
skills, including basic concepts, on space plasma
data analyses.
This sounds limited to space plasma, but it\'s not
true, I think.
Actually this course, in some senses, gave me hints
for analysis
techniques. I\'d like to say that these techniques are
just applied
to space plasma data analyses!
Anyhow, this course roughly consisted of:
1. Statistics
2. Spectral Analysis
3. Multivariate Analysis
4. Nonlinear Time Series Analysis
5. Neural Nets (Artificial Intelligence)
6. Others
I\'ll try to present what I\'ve become acquainted with
going through this
course. So this presentation will not be a technical
one.
Fast neutral atom imaging: A
journey to Mars, Mercury, and back. Seminar by Mats
Holmström, IRF Kiruna
In this talk, Mats Holmström will present
simulation results for,
and discuss:
* ENA albedo images, and directional fluxes, near
Mars,
* the imaging of sputtered very low energy neutral
atoms (VLENA),
* the distribution of neutrals and ions near
Mercury,
* a characteristic method for computing phase space
density, and
* an algorithm for fast volume rendering.
The Munin Plasma Data. Seminar by
Kan Ogawa (Japan)
In this seminar, Kan Ogawa will talk about the plasma
data observed by the Munin
satellite. The Munin satellite was launched on
November 21, 2000 and it
collected data for nearly 3 months. Also, he will
present the observed ion
injection events.
Framtiden för IRF:s
jonosonderingar med anledning av ett nytt anslag på
890 tkr från Kempestiftelserna. Seminar by Christer
Jurén, IRF Kiruna
* Matematisk beskrivning av \"tillväxt\" vid
IRF.
* Ansökan om en Miljon.
* Den historiska utvecklingen av jonosonderingen vid
IRF, FOA, Chalmers...och i hela världen.
* Jonosfären.
Are there clouds in the winter
mesosphere? Seminar by Sheila Kirkwood, IRF Kiruna
It is well known that clouds sometimes appear in the
winter stratosphere
(polar stratospheric clouds) and the summer
mesosphere (noctilucent
clouds). But it is generally believed that the
atmosphere above the
tropopause is otherwise free of clouds.
During the last year, the ESRAD MST radar has
observed thin layers of
enhanced radar echoes in the winter mesosphere (50-80
km altitudes) during
almost all of the solar proton events which have
ocurred. These layers are
extremely thin, highly aspect sensitive and are seen
only when the
mesosphere is illuminated by sunlight. Arguments will
be presented that
they are caused by thin layers of aerosols, i.e.
clouds?
En kamera är väl en
kamera? Ett seminarium om äpplen och päron.
Seminar by Urban Brändström, IRF Kiruna
Idag kan många olika sorters kameror avbilda
norrsken. Vad är skillnaden mellan en vanlig småbildskamera,
vår firmamentkamera från 1977, ALIS-kamerorna från 1994 och den nya
firmamentkameran från år 2000? Hur förhåller sig dessa instrument
till liknande instrument i våra grannländer? Är det skillnad
mellan rymd och markbaserade kameror? Varför går norrskensfilmerna
alltid för fort?
IRF har tidigare haft ett mycket aktivt och
innovativt forskningsprogram för optisk norrskensforskning.
En sammanfattning av de senaste tio årens verksamhet kommer att
ges.
En populärvetenskaplig film om optiska
mätningar, ca. 8 min speltid, kommer att visas under seminariets gång. (Samma
film som visades under Öppet hus).
Det kommer att vara gott om tid för diskussioner
och frågor.
Spring Semester 2001
11 January 2001
\"Modelling small-scale mountain lee-waves over
Kiruna\", by Sheila Kirkwood, IRF, Kiruna
[Abstract]
16 January 2001
\"The Munin Project\", by Olle Norberg, IRF,
Kiruna
13 February 2001
\"Simulations of Charge-Exchange Processes near
Mars\", by Mats Holmström, IRF, Kiruna
[Abstract]
15 February 2001
\"The Physics of the Cusp from an Interball
Perspective\", by Ingrid Sandahl, IRF, Kiruna
[Abstract]
22 February 2001
\"Numerical simulations of the One-Dimensional
Vlasov Equation\" by Bengt Eliasson, Departments of
Scientific Computing and Astronomy and Space
Physics, Uppsala [Abstract]
Friday, 23 February 2001 (10.30-11.30)
\"The Solar Wind and Geomagnetic Storms\" by Prof.
Y. Kamide, STE LAB, University of Nagoya, Japan
1 March 2001
\"Interplanetary Dust Studies using Large
Aperture Radars meteor observations\" by Diego
Janches, IRF, Kiruna
6 March 2001
Professor A. Suzuki, Saga University, Japan. A
seminar presenting his university, its
education/research system and his work on Magsat
satellite data.
15 March 2001
\"Energized heavy ions measured by Interball -2
satellite\" by Sachiko Joko, IRF, Kiruna
[Abstract]
16 March 2001
\"Lower Hybrid Cavities and Other Plasma
Phenomena in the Subauroral Region\" by Solveig
Høymork, IRF, Kiruna [Abstract]
22 March 2001, 10:00 (10 am)
\"Fine Structures in Auroral Emissions\" by Jim
LaBelle, Dartmouth College [Abstract]
22 March 2000, 13:30 (1.30 pm)
\"Wave Propagation in Inhomogeneous Plasmas\" by
Hans Pécseli, University of Oslo, Norway
[Abstract]
\"Direct Magnetosheath Plasma Injections into the
Closed Geomagnetic Field Region Observed at Mid-
and Low-altitudes\" by Yamauchi Masatoshi, IRF,
Kiruna [Abstract]
26 April 2001
\"Motion and Origin of the Noon Poleward Moving
Auroral Arcs\" by Alexander Kozlovsky, Oulu
University, Finland [Abstract]
8 May 2001
\"Imaging of PSCs in 0-3 dimensions\" by
Carl-Fredrik Enell, IRF, Kiruna [Abstract]
10 May 2001
\"Inertial Resistivity and Current Limitation in
a Collision-free and Inhomogeneous Plasma\" by
Martin Bohm, Department of Space Physics,
Umeå University, Kiruna [Abstract]
15 May 2001
\"The Frontal Systems, Fundamentals\", by Narayana
Rao, IRF, Kiruna
ABSTRACTS
\"Numerical simulations
of the One-Dimensional Vlasov Equation\", by Bengt
Eliasson, Department of Scientific Computing and
Department of Astronomy and Space Physics,
Uppsala
In order to facilitate numerical simulations
of plasma
phenomena where kinetic processes are
important, we have
studied the technique of Fourier
transforming the Vlasov equation
analytically in the velocity space, and
solving the resulting
equation numerically. Special attention has
been paid to the
boundary conditions of the Fourier
transformed system, avoiding
the so-called recurrence phenomenon.
I will make a short presentation of the
numerical techniques
and then present some numerical results; the
process of
electrons getting trapped in waves
(nonlinear Landau damping),
comparison with thery of linear waves
etc.
We are currently looking on a problem of
tunneling of information
throught the ionosphere, where the tunneling
may be caused by
electrons trapped in the self-consistent
electrostatic potential
due to the ion density profile. I will show
some
numerical results from this problem.
\"The physics of the cusp
from an Interball perspective\", by Ingrid Sandahl,
IRF
The Interball project has given important
contributions to our
understanding of the morphology and the
physical processes in the cusp and
cleft. Interball-Tail and Magion-4 have
performed more extensive
measurements in the high altitude cusp than
any previous spacecraft.
Interball has also been a part in the ISTP
program and data have been used
in many multipoint studies. In this paper
cusp studies based entirely or
partly on Interball data will be
reviewed.
The high altitude cusp/cleft is always a
clearly distinguishable feature.
It is wider than suggested by direct mapping
from low altitude, but the
position is controlled by the solar wind in
a similar way as the low
altitude cusp. The dependence of the high
altitude cusp position on IMF By
is, however, smaller than expected. Above
the cusp/cleft there is almost
always a region of strong ULF turbulence and
low magnetic field, the
turbulent boundary layer, TBL. The TBL
extends tailward from the cusps and
is proposed to be related to the
magnetospheric \"sash\".
The cusp is the site of very many physical
processes. It acts like a funnel
collecting magnetosheath plasma into the
magnetosphere. A number of
different plasma entry mechanisms are
supported by the data including
direct plasma entry through the turbulent
boundary layer, direct entry
along open high-latitude field lines,
sub-solar point reconnection, and
lobe reconnection. For the overall
magnetosheath plasma entry into the
magnetosphere, however, the magnetotail
boundary is probably more important than the
cusp.
Cusp energetic particles (Å 100 keV-MeV) are
observed by Interball, but
their origin is not well understood. One
view is that they have drifted to
the cusp from the ring current and outer
radiation belt.
Acceleration and outflow of ionospheric
plasma also take place in the cusp.
\"Simulations of
Charge-Exchange Processes near Mars\", by Mats
Holmström, IRF-Kiruna
Ions interact with neutrals by
charge-exchange.
We study the interaction between the solar
wind
and Mars\' exosphere.
The results of, and methods used in,
the
simulations of two different problems are
presented.
The production of energetic neutral atoms
(ENAs)
and the production of X-rays, near
Mars.
The production rate computations are based
on an
empirical proton flow model and an
exospheric model.
Using these parametric models, X-ray and ENA
images
are generated by line-of-sight
integration
(the forward problem).
The possibility of detecting the X-ray
emissions
from Mars and Venus using the X-ray
observatories
Chandra and XMM-Newton is discussed.
To speed up the computations and control the
error,
a new algorithm for evaluation of
line-of-sight
integrals is presented.
We also discuss the inverse problem of
extracting flow parameters from
measured
ENA and X-ray images.
\"Modelling small-scale
mountain lee-waves over Kiruna\", by Sheila
Kirkwood, IRF.
Nacreous clouds, the brightly coloured type
of polar straospheric clouds
which are often seen in the Kiruna area in
January, often show clear
wave structure. The wavelength of the wave
structures are of the order 30 km
or less. Model simulations of mountain lee
waves in the stratosphere using
the MM5 meteorological model have been made
for recent ozone research
campaigns by German and British groups.
However, the lee-waves in these
simulations have have wavelengths of 100 km
or more. There is clearly a
need to model the smaller-scale waves to aid
in interpretation of
photographic records of the clouds, and
ESRAD radar observations of the
vertical winds associated with
lee-waves.
In this seminar a relatively simple model
for small scale waves will be
presented. The model uses a 1-km resolution
digital terrain model over
northern Scandinavia, synoptic atmospheric
wind and buoyancy data from
UKMO assimilations and wave refrective index
and ray-tracing concepts as
described by Salby.
The audience are invited to discuss how this
model could be used in our
research and how it might usefully be
improved.
\"Energized heavy ions
measured by Interball-2 satellite\", by Sachiko
Joko, IRF.
*Joko, S., IRF-K, Sweden,
sachiko.joko@irf.se
Sandahl, I., IRF-K, Sweden,
ingrid.sandahl@irf.se
Yamauchi, M., IRF-K, Sweden,
masatoshi.yamauchi@irf.se
Sergienko, T., IRF-K, Sweden,
timothy.sergienko@irf.se
Upward moving heavy ions with energies of up
to at least 600 eV are
studied using the PROMICS-3 instrument on
board the Interball-2
(Aurora Probe) satellite. While many past
studies revealed O+ outflow
from the ionosphere, non-thermal escaping
heavy ions, like N2+, NO+
and O2+, have not been well investigated,
partly because of a lack of
proper instrumentation in previous mid- and
high-altitude satellites.
PROMICS-3 on board Interball-2 is capable of
measuring non-thermal
heavy ions because the instrument shares a
mass spectrometer mode
(1-64 amu/q for 100 eV and 600 eV positive
ions) and an energy
spectrometer mode (4 eV-70 keV ions for four
masses and 0.3-35 keV
electrons).
We have examined all the Interball-2
observations (October 1996 -
December 1999) of heavy ions (m/q > 16)
during geomagnetically
active periods (Kp >= 4). Heavy ions are
observed in all MLT, i.e., in the noon
(cusp), dawn, dusk and midnight. According
to the comparison between mass spectra
of upward moving heavy ions and the energy
spectra of H+, O+,He+ and
He++ in the transverse direction, heavy ions
events seem to be
associated with energized and upflowing O+
events.
These appear to be caused by large potential
drops, seen as the ion
beam energy and related to plasma injection
from the solar wind or the
plasma sheet.
Note:
1. \"Energized Heavy Ions\" should be changed
like this;
\"Molecular Ions\". Compared to other studies
on
this subject, 600eV that I\'m now focusing on
as a
fixed energy is much higher than others, but
I prefer
just saying \"molecular ions\" or \"heavy ions\"
(this
means \'heavier than lighter ions like O+ and
N+\').
2. I\'d like to clarify the physical
mechanism of \"molecular
ions upflowing (escaping from the Earth)\" as
the goal
of this study, but I\'m still under stastical
study, which
means that I also encourage audiences to
give me any ideas on this.
\"Lower Hybrid Cavities
and Other Plasma Phenomena in the Subauroral
Region\", by Solveig Høymork, IRF.
Solveig Høymork will present the main
points in her thesis which analyses data from
two Swedish satellites, Freja and Astrid-2.
These satellites orbited the earth over the
poles and took measurements in the auroral zone
at heights of 1700 km and 1000 km respectively.
This is the upper ionosphere where a large
proportion of the atoms are ionized, creating a
plasma. The study is restricted to the
subauroral region. This area is expected to be
less dynamic than the area in which aurora is
usually visible. Nevertheless exciting phenomena
occur there as well. Data shows localized
thinning in plasma density, known as cavities.
Both small-scale (ca 50 m) and large-scale (ca
1000 km) cavities have been observed. There are
many physical processes that can lower the local
density of plasma and thus create cavities, for
example wave-particle interaction, electric
fields and plasma transport. The thesis deals
with several different types of cavities and
localized higher density ion clouds, and gives
possible explanations as to why these
occur.
Both Freja and Astrid-2 were relatively
cheap satellites. They have supplied a wealth of
very interesting data and contributed to an
increased understanding of our universe and some
of the processes which affect its environment.
It is becoming increasingly important to
understand the environment in space , as more
and more human activity takes place there (for
example commercial satellites and space
travel).
\"Fine Structures in
Auroral Emissions\", by Jim LaBelle, Dartmouth
College.
The aurora emits a variety of types of radio
waves,
and most of these exhibit frequency fine
structure;
i.e., they are composed of multiple discrete
features
which often vary in frequency. This talk
addresses the
fine structure in two of these emissions:
auroral roar
and auroral Lanmuir waves. After reviewing
the experimental
evidence for the fine structure of these
emissions,
revealed in both ground-based and
rocket-borne wave
receiver data, we explore the possibility
that these
fine structures are consequences of the
inhomogeneity
inherent in the auroral plasma. We put forth
that both types
of fine structure may be explained by
considering wave
excitation in the presence of density
structures that
impose an eigenmode structure on the
waves.
\"Wave Propagation in
Inhomogeneous Plasmas\", by Hans Pécseli,
University of Oslo, Norway
Models for describing the properties of
waves propagating in inhomogeneous
plasmas are reviewed. Particular attention
is given to electron plasma
waves (Langmuir waves) in plasmas containing
density gradients, Alfvén
waves in inhomogeneous plasmas and ion sound
waves in magnetized plasmas with inhomogeneous
electron temperatures. It is shown how it can be
argued that these waves are not following any
dispersion relation for inhomogeneous
conditions, and the concept is then
\"de-mystified\".
\"Direct Magnetosheath Plasma
Injections into the Closed Geomagnetic Field Region
Observed at Mid- and Low-altitudes\", by M.
Yamauchi
Some decade ago observations of Viking
showed that direct solar wind
injection may occur deep inside the CPS
region. Since then other
observations of plasma injection into CPS
have been reported, from highly
transient injections to more stagnant ones
with different magnetic
(field-aligned current) signatures. Such
observations raises a question
identifying/defining the open-closed
boundary.
Satellite cusp observations in 1990\'s also
indicate that we do not have a
simple open-or-closed concept. It seems
necessary to introduce a fuzzy
concept for the openness of regions such as
\"semi-open\" and \"extra-open\"
(extra here means accessibility of
ionospheric ions to the magnetosheath).
We also report on recent searches for direct
plasma transfer with other
satellites. Interball-tail, from similar
altitudes, found similar types of
events. Freja, from low-altitude, sometimes
observes cusp-like injections
into early dawn and late dusk. Finally, data
from Astrid-2 display
characteristics of ion clouds which could be
attributed to direct
injections of the solar wind.
\"Motion and Origin of
the Noon Poleward Moving Auroral Arcs\", by
Alexander Kozlovsky, Oulu University,
Finland
Near-noon auroral arcs were investigated
together with the
ionospheric plasma flows derived from the
EISCAT VHF measurements over
Svalbard. The auroral arc motion was monitored
at 0800 - 1300 MLT by the
all-sky camera during four days in December
1998. It has been found that the
noon auroral arcs move poleward at the
velocity of the order of 200 - 600
m/s, and this velocity does not show any
dependence on the velocity of the
ionospheric plasma convection along the same
direction. The arcs appear at 5
- 15 min after strong changes (up to 4 km/s)
in the meridional plasma flow,
which resulted from variations in the
interplanetary magnetic field.
Particle precipitation data from DMSP
satellites show location of the
auroras on closed magnetic field lines in a
vicinity of the boundary between
BPS and LLBL. Spectrums of the northward
electric field variations measured
by the radar demonstrate clear peaks
corresponding to the FLR oscillations.
Period of the oscillations increases from 6
min at 74.3 MLAT to 14 min at
76.4 MLAT. Corresponding spectral
characteristics were observed in the
magnetic field measured on ground. The
observed features allow to suggest
that the noon auroral arcs arise as a result
of interference between Alfvén
field line eigenmode toroidal oscillations
on different L-shells. The FLR
oscillations at the near-cusp L-shells are
excited by the Alfvén impulse
associated with the convection disturbance
followed after variations in
interplanetary parameters.
\"Imaging of PSCs in 0-3
dimensions\" by Carl-Fredrik Enell
The method generally used in studies of
polar stratospheric clouds is
optical remote sensing from the ground,
balloons or satellites. This
can be thought of as imaging in 0-3
dimensions depending on the technique
used and the corresponding geometry.
This seminar is indended as a discussion
of the data we have available:
-Colour index
-Lidar
-Images
and the best ways to use and interpret
these data, including some
mathematical problems encountered in the
analysis.
Everybody is welcome to bring ther own
pictures, lists of PSC observations,
and so on.
\"Inertial Resistivity and
Current Limitation in a Collision-free and
Inhomogeneous Plasma\" by Martin Bohm, Department of
Space Physics, Umeå University,
Kiruna
Measurements in space show that a
collision-free plasma can support large
potential drops. In interplanetary space
collective processes, connected with plasma
turbulence, can assume the roll of
collisions. Inhomogeneous and collision-free
plasmas may support large potential drops on
the electron time scale even for
free-streaming electrons in time-independent
motion. This \"inertial resistivity\" has
recently been used to interpret measured
magnetic-field-aligned potential drops in the
auroral zone of the Earth. In the seminar the
results of one-dimensional particle-in-cell
simulations of the response of an
inhomogeneous plasma to a suddenly applied
high voltage drop Va are presented. The
results are compared with a theoretical model
of the inertial conductance and with
experiments. In the initial phase inertial
conductivity dominates. Then the simulations
show a sharp current drop associated with
turbulence and reflection of current carrying
electrons. In this case turbulent resistivity
is the likely current limiting
mechanism.
Autumn semester 2000
10 October 2000
Julien Forest, \"Modelling of Spacecraft-Plasma
Interactions (IPICSS Project): Introduction to the
Particle-In-Cells method and Presentation of the
PicUp3D/Spis system [Abstract]
11 October 2000
Dr. Alya Osepian, PGI Murmansk, \"A pulsating
regime of whistler cyclotron instability\"
12 October 2000
Shu T. Lai, Space Vehicles Directorate, Air
Force Research Laboratory, Hanscom AFB., MA,
\"Electron Temperature as a Key Parameter for
Predicting Spacecraft Charging in Changing Space
Weather\" [Abstract]
17 October 2000
Rickard Lundin, \"Planetary Plasma Acceleration
Processes: Implications on Astrophysics\"
[Abstract]
26 October 2000
Yusuke Ebihara, \"Wedge-Like Ion Dispersion in
the Inner Magnetosphere: Viking Observation and
Particle Simulation\" [Abstract]
31 October 2000
Takayuki Kanda, \"A brief introduction to our
group in Tohoku University and my background in
space physics\" [Abstract]
7 November 2000
Uwe Raffalski, \"The SOLVE/Theseo2000 ozone loss
campaign in Kiruna during winter1999/2000. Part 1:
An overview\" [Abstract]
9 November 2000
Hans Nilsson, \"EISCAT and DMSP observations of
the quiet time evening sector ionosphere\"
[Abstract]
ABSTRACTS
Julien Forest, \"Modelling of
Spacecraft-Plasma Interactions (IPICSS Project):
Introduction to the Particle-In-Cells method and
Presentation of the PicUp3D/Spis system
The orbital structures (e.g. spacecraft) are in intimate
interaction with the environment created by the space
plasma. By simple contact, a large number of charged
particles (electrons, ions) hit its external surface. Added
to the ionisation effect by Sun UV or high energy particles,
this leads to the accumulation of a net electrical charge on
the spacecraft, inducing itself an electrostatic difference
of potential between the satellite and the plasma.
This mechanism, called spacecraft-charging, and more
generally the modifications of the spacecraft electrostatic
environment, have many scientific and technological
consequences, with sometimes as final conclusion the loss of
satellite.
In the context of an European network, the IPICSS
project, for Investigation of Plasma Induced Charging of
Satellite Systems, had as objectives a complete analysis of
these effects on modern satellites and scientific systems,
including instrument calibration and in-flight
interpretations. Its first goal was to find new mathematical
models and test new numerical tools for more advanced and
accurate simulations. This effort has led to the detailed
study of the Particle-In-Cell (PIC), method initially issue
from the hot plasma domain. This work was concretised be the
development of a experimental simulation code, PicUp3D/Spis,
based on a complete 3D PIC approach and fully written in
JAVA. On a computing side, this effort of development has
allowed to check in details the increasing possibilities of
the JAVA language and the free, or open sources, softwares
for intensive numerical simulations and scientific
visualisation. The final results of the IPICSS project and
the PicUp3D/Spis code are presented here. In addition, a
discussion about these new computing approaches can be
opened.
Shu T. Lai, Space Vehicles Directorate,
Air Force Research Laboratory, Hanscom AFB., MA, \"Electron
Temperature as a Key Parameter for Predicting Spacecraft
Charging in Changing Space Weather\"
The space plasma electron temperature, Te, is a key
parameter for predicting spacecraft surface charging. Two
important properties are discussed: (1) the onset of
spacecraft charging depends on a critical, or threshold,
temperature, which depends on the surface materials, and (2)
the approximately linear dependence of surface charging
potential on the ambient plasma temperature in a Maxwellian
space plasma. The onset of spacecraft charging in a
Maxwellian space environment is independent of the ambient
electron density, ion density, and ion temperature, but
depends solely on a critical, or threshold, electron
temperature. Below it, no spacecraft charging occurs; above
it, spacecraft charging occurs. The current balance between
the incoming and outgoing electrons gives an indeterminate
spacecraft surface potential. The potential has to be
determined by the balance between the incoming electrons,
outgoing electrons, and the ambient ions. Other significant
currents such as photo-electron or artificial beam
emissions, if present, have to be included. The collection
of currents by a spacecraft at geosynchronous altitudes is
well described by the Langmuir probe formulation in the
orbit-limited regime. That is, the spacecraft behaves like a
Langmuir probe. Whereas the currents respond to an applied
voltage on a Langmuir probe in the laboratory, the
spacecraft potential V responds to the currents in space.
For eV < kT, Taylor expansion of the current balance
equation immediately gives the linear dependence of the
spacecraft potential on the ambient electron temperature T,
approximately. We present abundant evidences from ATS-5,
ATS-6, LANL-90, LANL-94, and LANL-97 satellite data to
support our contention of the two properties. Amazingly,
surface potentials measured day after day on several
satellite over several years confirm the existence of a
critical temperature and the approximate linear dependence
properties. We discuss limitations of the formulation. We
also extend our discussion to non-spherical spacecraft
geometry, double Maxwellian space plasma environments,
including of photoelectrons, and beam emissions. Heretofore,
photoelectron currents have been assumed to be one to two
orders of magnitude larger than ambient electrons and ion
currents. We explain physical mechanisms why only a small
fraction of the photoelectrons can leave from a
differentially and negatively charged spacecraft. Curve
fitting using LANL-94 data shows that the fraction is indeed
smaller than previously thought. Finally, we discuss the
surprising good agreement between the Maxwellian theory and
the satellite charging data.
Rickard Lundin, \"Planetary Plasma
Acceleration Processes: Implications on Astrophysics\"
Contemporary space plasma
physics have demonstrated that non-thermal energization and
outflow of plasma is an important process for the loss of
matter from celestial objects. The losses are due to
internal processes, such as those occuring in stars like our
own sun (the solar wind) or due to external/scavenging
process by a stellar/solar wind impacting on neighbouring
objects, e.g. comets, planets etc. Strongly magnetized
objects, prohibiting a direct \"scavenging\" interaction, are
losing matter by a process denoted charge exchange. Charge
exchange is a process where energetic ions become
neutralized by interacting with neutral atoms, thererby
producing fast neutral atoms. In this way a fast \"wind\" of
energetic neutrals is produced by hot plasma interacting
with a neutral gas. Charge enchange have long been known to
represent a major loss process for \"stably\" trapped
energetic ions in planetary magnetospheres such as those for
the Earth, Jupiter and Saturn. In this way one may consider
planetary magnetospheres as objects \"radiating\" energetic
neutral atoms into space.
In this report we consider other
celestial objects such as stars and galaxies and compare
them with planetarys magnetospheres. We point to the fact
that stars and galaxies are also likely to \"shine\" of
energetic neutral atoms. Depending on the locus of
observation an observer will experience a blueshift or
redshift of the light emitted/absorbed by the neutral wind.
For instance, the Lyman alpha emissions from the wind of
neutral hydrogen emitted from the Sun by charge exchange
will be primarily redshifted, except in the direction
pointing directly towards the Sun. The net outward wind of
ENA:s from the ensamble of stars within a galaxy is expected
to lead to a similar results for an observer situated within
the galaxy, that is primarily a redshift of
emission/absorbtion lines from the expanding neutral
wind.
Although the galactic ENA-wind is not
the only factor leading to a redshift of astrophysical
objects outside our own galaxy, it yet remains an important
factor that must be considered when discussing
dopplershifted absorbtion and emission lines. We will
present examples of stars and galaxies where this is quite
obvious.
Yusuke
Ebihara, \"Wedge-Like Ion Dispersion in the Inner
Magnetosphere: Viking Observation and Particle
Simulation\"
In the dayside inner magnetosphere, Viking ion detectors often observed
dispersed structures of sub-keV ions (\"wedge-like\" dispersion), which had
not been understood well. We have proposed a possible process producing them
by means of a single particle simulation. Finally, they are found to be
results of temporal and spatial changes in the density (or temperature)
structure in the nightside plasma sheet. This analysis will enable us to
monitor remotely variations of density(temperature) structure in the
near-earth plasma sheet if this method is valid and established.
Takayuki
Kanda, \"A brief introduction to our group in Tohoku
University and my background in space physics\"
The seminar will be a short introduction to our laboratory\'s works
and my background in space physics in order to have you know
the phenomena, which I have been interested in and I have studied,
before I start my work at IRF.
Division of Space Physics in Tohoku University is one of the
largest space-research organizations in Japan, which consists
of four groups, electromagnetism of Space and Earth Group,
Planetary Atmosphere Physics Group, Planetary Radio Wave
Science Group, and Planetary Optical Emission Science Group.
The latter two groups are parts of Planetary Plasma and
Atmospheric Research Center (PPARC), which was established
in April 1999. We research a variety of phenomena from the
atmosphere up to space in the solar system, such as airglow,
aurora, planetary atmosphere, planetary radio waves/optical
emissions, and so on.
I am a currently graduate student in Master\'s programme and
a member of Planetary Radio Science Group in PPARC. In the
talk I would like to review our group\'s works and my studies.
Our common purpose is to reveal the physical processes
produced in planetary plasma and atmosphere by observations
of planetary radio waves and using data measured by spacecrafts,
and our targets are mainly the electro-magnetic dynamics,
acceleration process of energetic particles, and auroral
phenomena (including studies on related plasma waves and
particles) in the terrestrial and Jupiter\'s magnetosphere.
I would like to present some topics of them, that is,
observations of the decimeter radio waves which are generated
by synchrotron radiation from relativistic electrons in the inner
Jovian magnetosphere, the dynamics of energetic electrons in
the radiation belt during geomagnetic storms, and the
morphological study on black aurora.
I began to study electron acceleration mechanisms this spring,
and I have been very interested in suprathermal electron bursts
phenomena(STEB) which might be related to black aurora in the
low-altitude region. Therefore I am just looking through all
electron data measured by Freja satellite and searching for
interesting events such as STEB.
Uwe
Raffalski, \"The SOLVE/Theseo2000 ozone loss campaign in
Kiruna during winter1999/2000. Part 1: An overview\"
This presentation addresses the interested audience even with little
knowledge on stratospheric research. I will present a general overview
over the campaign without going into technical details of instruments
and techniques involved. I will rather present basic information, for
instance the the climatology of the winter, the development of the
vortex and some interesting measurements from the campaign. The
collected data show a significant ozone depletion during the course of
the winter. This will be presented and compared to earlier winters.
Since the role of polar stratospheric clouds has been studied during the
winter, some of the findings will be presented here as well, not without
showing some nice pictures from January and February, when there were
strong PSC events.
A second part of this presentation will be given later in the year with
some more detailed discussion of certain measurements and findings and
it will address to the even more interested audience.
Hans Nilsson,
\"EISCAT and DMSP observations of the quiet time evening
sector ionosphere\"
A combination of EISCAT CP-3 data (latitude scans) and DMSP
observations of charged particle precipitation has been used to study
the structure of the evening sector auroral and subauroral
ionosphere. We seek to establish the interrelationship between
electric fields, conductance structures, F region structures (i.e.
the trough) and proton precipitation. In particular we try to compare
the most common explananation for the formation of the main
ionospheric trough, that through the decay of F region plasma due to
long residence time in darkness, with the theory for auroral cavity
formation in which F region thermal plasma carries a downward
field-aligned current (FAC) which leads to an evacuation of E and F
region plasma in the current region. The region of downward FAC in
the evening sector (i.e. the region 2 current) is also associated
with proton precipitation. We show how most proton precipitation
regions are closely associated with the most equatorward region of
wesward flows, i.e. northward electric fields, in the auroral
ionosphere. The proton precipitation is charge exchange spread, and
it is experimentally shown how large this spread is, and how the
resulting conductance structure is smoothly spread into the lower
latitude region with low flows (i.e. corotating ionospheric plasma).
This spread allows for a smooth and simple relation beween the
electric field and associated field-aligned currents. We discuss
whether the existence of proton precipitation in association with the
trough can be used to diagnose the convective history of the plasma
in the trough (with we I mean all of us attending the seminar).
Finally, can we say something about the proton precipitation? Why are
the proton scattered into the loss cone and precipitated? Can this
dataset give a clue?
GENERAL SEMINARS, Spring Semester
2000
23 May 2000
\"My experience as an environmental researcher\",
by Sachiko Joki
9 May 2000
Henrik Svensmark, Danish Space Research
Institute [Abstract]
2 May 2000
\"What does a single number say about a winter\'s
ozone depletion?\" by Johan Arvelius [Abstract]
4 April 2000
\"Some aspects on Incoherent-Scatter Radars\" by
Micce Hedin [Abstract]
28 March 2000
\"Some notes about past, present and future
Ionosondes in Sweden\" by Christer Jurén
[Abstract]
21 March 2000
\"Why study IRF? A presentation of Science &
Technology Studies(STS)\" by Marta Nyborg,
Linköping University [Abstract]
14 March 2000
\"Global atmospheric electric circuit and
geomagnetic substorm interrelation: a possible new
link between solar and terrestrial phenomena?\" by
Evgenia Belova [Abstract]
7 March 2000
Olle Norberg
29 February 2000
\"Climate forcing by anthropogenic aerosols\", by
Robert Charlson, USA
15 February 2000
Winter Cities Conference in central Kiruna
8 February 2000
Yasuhito
1 February 2000
Tima Sergienko
24 January 2000
\"The cusp as seen from Interball\" by Ingrid
Sandahl [Abstract]
11 January 2000
\"Direct plasma acceleration by the radiation?\"
by M. Yamauchi [Abstract]
SPACE PLASMA SEMINARS, Spring
Semester 2000
6 April 2000
\"Radar Micrometeors studies at Arecibo - an
overview\" Diego Janches, USA [Abstract]
23 March 2000
\"What is the big difference between biological
and technical image processing?\"Thomas
Lindblad, KTH [Abstract]
10 February 2000
\"Dynamic Trapping of Electrons in Space Plasmas\"
by Martin Bohm [Abstract]
27 January 2000
Ingemar Häggström
* To confirm dates and seminar-holders, contact the seminar
co-ordinator, Bruno Aparicio, bruno.aparicio@irf.se
(tel. +46-980-79086) *
ABSTRACTS
Henrik Svensmark, Danish Space
Research Institute
Satellite data have revealed a striking correlation
between the intensity of galactic cosmic rays (GCR) and low
liquid clouds ( < 3 km). GCR is responsible for nearly
all ionisation in the atmosphere below 35 km. However, a
direct link between GCR and cloud formation is yet to be
unambiguously established and, moreover, the microphysical
mechanism is not understood. One mechanism could involve
aerosol particles (0.001- 1 mu in diameter) and the
formation of cloud condensation nuclei (CCN). A systematic
variation in the properties of CCN will affect the cloud
droplet distribution and thereby influence the radiative
properties of clouds. If the GCR/Cloud link is confirmed,
variations in galactic cosmic ray flux, caused by changes in
the solar activity could influence Earth\'s radiation energy
budget. In particular the magnetic flux carried by the solar
wind has more than doubled during the last 100 years, at the
same time as the global temperature has risen.
In the talk we will show a few examples that demonstrate
remarkable correlation between solar activity and climate.
The possible link between solar activity and clouds will be
discussed. Finally plans to test the link under controlled
laboratory conditions in a particle beam at CERN with a
cloud chamber, will be presented.
\"What does a single number say
about a winter\'s ozone depletion?\" by Johan Arvelius
In a pressrelease from the European Commission\'s
Research Directorates-General we could all read that
there has been an ozone-loss of 60% at 475K level this
season.
Ozone depetion over a large area and a full season is
a quite different task to deal with. Estimations of the
chemical depletion of ozone in the arctic over the winter
is a complex and burning research topic involving a lot
of different mesurements and simulation.
The seminar will be a short review of polar
atmospheric science mainly at stratospheric levels under
winter conditions.
The headlines from last week that talked about 60%
ozone depletion at certain heights will be discussed and
I hope you should get a more realistic picture of this
year\'s ozone depletion.
\"Radar Micrometeors studies at
Arecibo - an overview\" by Diego Janches, USA
UHF radar meteor observation have seen a rebirth
after almost 30 years
(Evans, J. Geophys. Res., 70, 1965) starting with the
pioneering work of
Pellinen-Wannberg and Wannberg (J. Geophys. Res., 99,
1994). Following
this work, a similar line of research grew at Arecibo
Observatory (AO)
from incoherent scatter radar observations of the
ionosphere, where
meteors were simply treated as measurement-noise, to
a distinctly
different scientific focus. Data-taking and analysis
capabilities
reached a high enough degree of sophistication that
meteors could be
observed with the current 150 m and 1 ms range and
time resolutions,
respectively, at the 430 MHz radar frequency. These
measurements are
very distinct from the classical HF/VHF radar
observations in that the
head-echo (radar scattering from the region
immediately surrounding the
meteoroid) is always observed leading uniquely to
very accurate speed
determinations. We have developed a multi-pulse
Doppler technique that
permits the direct measurement of Doppler velocities
from the
micrometeor leading-edge (or head-echo) and in some
cases micrometeor
deceleration. The realization of highly resolved
meteor altitudes,
velocities and deceleration are crucial for
understanding a number of
aeronomical and astronomical problems. Particle sizes
and masses can be
estimated from these results, which are needed to
estimate the meteoric
mass flux in the upper atmosphere. Extra-atmospheric
speed can also be
determined if the mass-loss mechanisms that these
particles undergo are
understood. These speeds are essential for the
determination of dust
orbital parameters. More than 7000 and 3000 events
detected during the
Leonids 1997 and 1998 period respectively were so far
analyzed.
Approximately 10% of these manifest deceleration. An
overview of the
results obtained so far is discussed.
\"Some aspects on Incoherent-Scatter
Radars\" by Micce Hedin
I will present and discuss selected parts from the
theory of IS-radars
(eg EISCAT). The focus will be put on parts where
approximations are
done, and where a priori assumptions are made about
the ionosphere.
\"Some notes about past, present and
future Ionosondes in Sweden\" by Christer Jurén
In the past Sweden had a well-known reputation in
shortwave sounding of
the ionosphere. The sounding had its culmination
during the 60\'s. The first
ionosondes in Sweden were built during the 40\'s by
two almost independent
groups: one scientific and one which focused on
prognosis service for
shortwave propagation. Today all ionosondes in Sweden
are handled by the
Swedish Institute of Space Physics with its
headquarters in Kiruna. They
are mainly used in connection with aurora research
but data are also sent
all over the world for use in space weather prognoses
and in prognosis of
the state of the ionosphere related to short radio
wave propagation.
The above is described with the help of
audio-visualisations on a computer
connected to the Net.
The theory of radio wave propagation in the
ionosphere is discussed from an
historical point of view as an introduction to the
modern development of
the shortwave sounding of the ionosphere over
Sweden.
Finally the relation to other similar instruments in
the world,
Dynasondes, Digisondes, Candi etc., is described
together with the
planned sounding activity in Sweden during the next
solar cycle (the year
2000).
\"What is the big difference
between biological and technical imageprocessing?\" Thomas Lindblad, KTH
Even small kids can see if there is an animal in a
picture flashed during
20 ms while a computer easily mistakes some sunflowers
for a tiger. So
what is the big difference between biological and
technical image
processing? After all the \"speed\" of becoming aware of
things, i.e the
operations in the visual cortex, is only slightly higher
than \"video rate\"
The answer is that the processing is done in a very
cleaver manner in the
mid-brain. One typical thing is that there are more
feedback signals than
feedforward signals. Perhaps there is one or two lessons
to be learnt for
the next generation of smart sensors.
\"Why study IRF? A presentation of
Science & Technology Studies(STS)\" by Marta Nyborg,
Linköping University
Jag kommer från Linköpings Universitet och
har varit här sedan januari. Jag
gör en studie på IRF som ingår i mitt
avhandlingsprojekt \"Från pojkdröm
till könsblandad vetenskap - svensk rymdforskning\".
(Med \"svensk
rymdforskning\" menas också
atmosfärsforskning!).
På seminariet kommer jag att prata lite om min
hemmainstitution, Tema i
Linköping; den samhällsvetenskapliga
forskningstradition som jag tillhör
(STS); genus (= \"det socialt konstruerade
könet\")/vetenskap/teknik och till
slut en del om varför jag valde IRF som plats
för min fältstudie.
\"Global atmospheric electric circuit
and geomagnetic substorm interrelation: a possible new
link between solar and terrestrial phenomena?\" by Evgenia
Belova
The modern scientific point of view on the global
atmospheric electric
circuit will be presented. The three main generators,
or energy sources, of
this circuit are believed to be thunderstorms, the
ionospheric dynamo
(tides) and the solar wind/magnetosphere dynamo.
Thunderstorms, which occur
mostly at equatorial and subequatorial latitudes
maintain the potential
difference of 150-600 kV between the ground and the
ionosphere. Tides in
the ionosphere lead to the appearance of a horizontal
potential difference
of 5-15 kV between high and low latitudes at
ionospheric heights. Solar
wind-magnetosphere coupling results in an additional
ionospheric potential
drop of 40-100 kV across the polar caps. Main
attention in this
presentation will be paid on contribution of the
solar wind/magnetosphere
dynamo generator into this electric system.
The geomagnetic substorm is a common phenomenon at
high latitudes. The
distribution of the ionospheric electric field and
conductivity are known
to change in characteristic ways during substorms, so
substorms could
provide an additional ionospheric source of large
enough horizontal scale
to contribute to the local atmospheric electric
current.
We have analysed air-earth vertical currents (AECs)
measured by a long wire
antenna at Esrange, northern Sweden during 35
geomagnetic substorms. Using
superposed epoch analysis we compare the air-earth
current variation during
the 3 hours before and after the time of the magnetic
X-component minimum
with that for corresponding local times on 35 days
without substorms. After
elimination of the average daily variation we can
conclude that the effect
of substorms on AEC is distinguishable but small.
During about 2 hours
before the time of geomagnetic X-component minimum,
the AEC increases
probably due to enhancement of the ionospheric
electric field. To explain
these results we analyse the data on ionospheric
electric field measured by
STARE above Tromso, Norway. The results of analytical
modelling will also
be presented.
Because the geomagnetic substorms are associated with
changes in the
interplanetary magnetic field, the obtained effect in
AEC could be
considered as one more channel for solar-atmospheric
interaction. Different
others suggestions on the role of the global
atmospheric circuit in
relation between solar variability and climate will
also be discussed.
\"Dynamic Trapping of Electrons in Space
Plasmas\", by Martin Bohm
The neutralization of positive space charge is
studied in a case where
heavy positive ions are added to a limited region of
length L in a
collisionfree magnetized plasma. It is found that
electrons which become
accelerated towards the positive space charge can
only achieve a partial
neutalization: they overshoot, and the positive
region becomes surrounded
by negative space charges which screen the electric
field from the
surroundings. The process is studied both
analytically and by computer
simulations with consistent results: large positive
potentials (U>>kte/e)
can be built up with respect to the surrounding
plasma. In the process of
growth, the potential maximum traps electrons in
transit so that
quasineutrality is maintained. The potential U is
proportional to the
ambient electron temperature and the square of the
plasma density increase,
but independent of both the ion injection rate and
the length L.
The process explains several features of the
Porcupine xenon beam injection experiment.
\"The cusp as seen from Interball\" by
Ingrid Sandahl
The Interball project is very well suited for cusp/cleft
studies. Interball-Tail and its subsatellite Magion-4 visit
the cusp at several altitudes, and also traverse the
external cusp during both quiet and disturbed conditions,
while Interball-Auroral and Magion-5 cross the cusp at lower
altitudes. In this paper, cusp results from Interball will
be reviewed and some new observations will be presented. The
data from Interball show that the cusp is always a clearly
distinguishable feature, but that the location of the
external cusp, as well as the plasma behavior changes
dramatically with solar wind condi-tions. A number of
different entry mechanisms are supported by the data,
including sub-solar point recon-nection, high latitude flank
reconnection leading to entry along open field lines at high
latitude, lobe re-connection, and direct entry through the
turbulent, low-B-field outer cusp region. Plasma entry from
high lati-tudes seems to be more important than thought
earlier. The plasma flow in the magnetosheath outside the
cusp displays a complicated pattern and high latitude lobe
field lines are strongly indented.
\"Direct plasma acceleration by the
radiation?\" by M. Yamauchi
Although the solar radiation carries 1000 times more momentum than the
solar wind at 1 AU, the direct solar wind acceleration by photon has been
considered negligible because the cross section of the Thomson scattering
is extremely small.
However, the theory of the Thomson scattering is not perfect because the
effect of the plasma state has not been included. Since a simple
displacement of a charged particle causes a shift of electric potential
which is comparable to the energy of the incident wave (1-10 eV), the
collision cross section might be enhanced if we consider the plasma state
and background electric/magnetic field, e.g., via transient absorption
through which the radiation looses very little energy.
So far no laboratory experiment examined such scenario.
Therefore, it is worth while to examine the conditions/consequences for
direct acceleration of protons and electrons by the UV and visible light.
If this process works, it might explain :
(1) additional substantial momentum flux of the solar wind;
(2) lower solar constant during the solar maximum than during the solar
minimum;
(3) fast solar wind flow from the coronal hole;
(4) a part of the angular momentum of the super-rotation of Venus upper
atmosphere; and
(5) a part of the red-shift of spectrum from distant galaxies.
The last consequence requires revision of the Hubble constant.
AUTUMN 1999
14 December 1999
\"Ring current proton precipitation and its
consequence to the ionosphere\" by Yusuke Ebihara
[Abstract]
25 November 1999
\" Source and loss processes of magnetospheric
plasma\" by Bengt Hultqvist
23 November 1999
\"Artificial airglow and analysis of ALIS data\"
by Björn Gustavsson [Abstract]
16 November 1999
Seminarium: Origin of Life, Hans Nilsson och
Ingrid Sandahl [Abstract]
11 November 1999
\"Meteorskur värdig millennieskiftet?\" by
Asta-Pellinen-Wannberg [Abstract]
9 November 1999
\"ENA Imaging of Planetary Magnetospheres\" by
Pontus C:son Brandt [Abstract]
ABSTRACTS
\"Ring current proton precipitation
and its consequence to the ionosphere\" by Yusuke
Ebihara
EISCAT incoherent radar measurements are compared with
precipitating particle data from Viking and DMSP satellites
and numerical simulations to reveal a role of the
precipitating ring current protons (1-100 keV) to electron
production in the auroral E region. It has been pointed out
that precipitating protons enhance significantly the
electron density in the auroral E region as compared with
that due to precipitating electrons. However the spatial and
temporal variation of the ionization structure due to
precipitating protons has not yet been understood. We
simulate the motion of ring current protons and calculate
the precipitating proton flux. If we assume that the trapped
protons are scattered into the loss cone with a
characteristic time scale of the strong diffusion limit, the
results fairly account for the lower latitude portion of the
ionization structure measured by EISCAT.
\"Artificial airglow and analysis of
ALIS data\" by Björn Gustavsson
Today\'s seminar will show the observations of
artificially enhanced airglow produced by the EISCAT-Heating
facility in Tromsø. Detailed image analysis can
reveal some physically interesting charateristics of the
enhanced airglow, such as:
* Characteristic lifetimes of O1D
* Time evolution of O1D excitation
* Spatial structure of airglow emission
in 3D
The current theories will be compared with the ALIS
observations.
Seminarium: Origin of Life, report by
Hans Nilsson och Ingrid Sandahl
Some thoughts, notes and impressions from the Origin of
Life workshop in Sigtuna 27 - 29 October and a discussion on
if and how IRF and space physics can contribute to the
subject. Rosetta and Mars Express were the two future
missions where IRF Kiruna participates which were most
frequently mentioned during the workshop. Yama and Jan-Erik
Wahlund (Cassini) have been thinking about \'homochirality\',
and Yama has proposed possible future balloon missions.
\"Meteorskur värdig
millennieskiftet?\" by Asta-Pellinen-Wannberg
Natten till den 18 november återkommer meteorskuren
Leoniderna. En meteorskur uppträder när jorden
går igenom en kometbana och träffas av utspridd
kometstoft. Leonidernas moderkomet är 55P/Tempel-Tuttle
med 33-års period, och den besökte det centrala
solsystemet på våren 1998. År 1833
bjöd Leoniderna på det mäktigaste naturliga
fyrverkeriet som någonsin observerats med miljontals
stjärnfall under några intensiva timmar.
Troligtvis kommer vi inte att uppleva något
så intensivt i år, men det är kanske
ändå den bästa chansen i vår livstid.
Prognoserna för årets meteorsvärm varierar
kraftigt. Vissa experter påstår att aktiviteten
skulle ha varit som högst 1998, andra menar att den
maximerar i år. Man förväntar sig allt
från inga förhöjda flöden alls upp till
100 000 meteorer per timme. Före fjolårets
Leonidsvärm bröt full panik ut i världens
stora rymdorganisationer då man insåg att den
jordnära rymden skulle fyllas av stoft som närmade
sig jorden med 70 kilometer i sekunden. Kanske dels på
grund av alla försiktighetsåtgärderna
rapporterades inga skador på satelliter, men det
observerade meteorflödet var inte heller speciellt
högt - bara några hundra per timme som bäst.
Fjolårets erfarenheter och resultat diskuteras,
årets planerade mätningar samt
förväntningar så väl för gemene
man som forskare och satellitoperatörer kommer att
spekuleras.
\"ENA Imaging of Planetary
Magnetospheres\" by Pontus C:son Brandt
What do we mean by \"imaging\" and why is it important? And
what are \"ENAs\" and what makes them so special in
magnetospheric physics? These questions will be answered and
not until the audience understands the answers I will give
glimpse of the results from the microsatellite Astrid-1 and
some of the simulation results from Mercury. If time
permits, additional ENA sources will be discussed.
AUTUMN 1998
IRF popular or general seminar
IRF plasma seminar (PS)
IRF atmospheric seminar (AS)
02/09 8:45-17:20 ENA imaging at Mars. Workshop
03/09 09:00-17:55 ENA imaging at Mars. Workshop
08/09 Dr. Uwe Feucht, German Space Operations Center Section Space Flight Dynamics
10/09 Kerstin Stebel (AS)
15/09 Mikael Hedin
17/09 PS: Plasma conference reports
Laila Andersson
Yamauchi
Solveig Kjus
24/9 Sheila Kirkwood (AS)
25/09 Sheila Kirkwood Professorsinstallation
29/09 Assar Westman (popular seminar)
01/10 Solveig Kjus (PS)
06/10 Pontus C:son Brandt, Overview of Basic Plasma Theory - Review of the
Culham Summer School in Plasma Physics
08/10 Uwe Raffalski (AS)
13/10 Barbara Popielawska
15/10 Björn Gustavsson (PS)
20/10 Sten Yngström
22/10 Carl-Fredrik Enell (AS)
29/10 Laila Andersson (PS)
03/11 Urban Brändström
10/11 Asta Pellinen-Wannberg (popular), Leonids are coming!!!
12/11 Ulrik Eklund (PS)
19/11 Johan Arvelius (AS)
24/11 Arndt Meier (popular), Vetenskap ur fågelperspektivet
01/12 Martin Bohm
03/12 Arndt Meier (AS), Results from the NDSC intercomparison and some recent
work