Cluster Mission Conference Presentations



XXVI EGS General Assembly, Nice, 25-30 March 2001

  Proceedings published in: ST6.CLUSTER II - the first results, Geophysical Research Abstracts (2001) Vol. 3   Alleyne, H.StC., Balikhin, M.A., N., W.S., Yearby, K., Gustafsson, G.G., André , M., Cornilleau-Wehrlin, N. and Décréau, P.M.E.

Magnetosheath waves from Cluster 

Alleyne, H.StC., Yearby, K., Balikhin, M., Walker, S., Cornilleau-Wehrlin, N., Décréau, P.M.E., Gurnett, D. and Gustafsson, G.

DWP correlative results from the WEC instruments on cluster (Solicited Paper).

André, M., Gustafsson, G., Behlke, R., Carozzi, T., Eriksson, A., Khotyaintsev, Y., Tjulin, A., Vaivads, A., Wahlund, J.-E. and Cornilleau-Wehrlin, N .

Overview of multi-satellite observations of waves 

Behlke, R., André, M., Pedersen, A., Opgenoorth, H. and Eglitis, P.

Characteristics of electric field and wave signatures measured by the Cluster satellites during magnetopause crossings

Cully, C., André, M., Carozzi, T., Pedersen, A., Jackel, B., Pitout, F., Donovan, E., Opgenoorth, H. and Reme, H.

Multisatellite observations of mesoscale electrostatic structures in the outer cusp 

Gustafsson, G.; Ahlen, L.; Eriksson, A. I.; Gunnarsson. H.; Lundgren, A.; Thomas, H.; Berg, P.; Harvey, P.; Khyunge, K. 

The electric field and wave experiment on Cluster

PS12. Space instrumentation (co-sponsored by ST and GI), Geophysical Research Abstracts (2001) Vol. 3 

Gustafsson, G., André, M., Alleyne, H. STC., Blomberg, L., Bostrom, R., Carozzi, T., Cattell, C., Cornilleau-Wehrlin, N., P. Décréau, A. Egeland,, A. Eriksson, C-G. Falthammar, R. Grard, D. Gurnett, C. Harvey, B. Holback, G. Holmgren, O. Holter, J. Holtet, P. Kellogg, Y. Khotyaintsev, P. Kintner, S. Klimov), H. Laakso, J-P. Lebreton, P-A. Lindqvist, B. Lybekk, R. Manning, M. Maksimovic, G. Marklund, N. Maynard, J. Moen, F. Mozer, K. Mursula, H. Opgenoorth, A. Pedersen, H. Pecseli, R. Pfaff, B. Popielawska, I. Roth, A. Roux, H. Singer, K. Stasiewicz, R. Schmidt, P. Tanskanen, M. Temerin, O. Thrane, J-E. Wahlund, J. Wygant

An overview of early results from the Electric Field and Wave investigation on Cluster(Solicited Paper). 

Gustafsson, G., Mursula, K., Carozzi, T., Lybekk, B., Stasiewicz, K., Tanskanen, P., Singer, H. and Laakso, H.

ULF observations on Cluster 

Khotyaintsev, Y., Stasiewicz, K., Eriksson, A. and André, M.

On wave related density structures 

Khotyaintsev, Y., Stasiewicz, K. and Khotyaintsev, M.

3D Visualization of Cluster data with OVT 

Laakso, H., Grard, R., Masson, A., Escoubet, P., Lebreton, J.-P. and André, M., et al

Comparison between bulk electron densities and potential difference measurements on the Cluster satellites 

Lindqvist, P.-A., Marklund, G., Mozer, F.S., Bale, S., Hull, A., André, M., Gustafsson, G., Eriksson, A. and Pedersen, A.

Electric field and plasma density mesurements at Cluster magnetopause crossings 

Marklund, G., Lindqvist, P.-A. , Karlsson, T., André, M. and Gustafsson, G.

A search for large-amplitude electric field structures using Cluster multi-point observations near perigee 

Moen, J., Holtet, J.A., Pedersen, A., Lybekk, B., Oksavik, K., Østgaard , N. and Gustafsson, G.

CLUSTER observations related to postnoon auroral arcs 

Pedersen, A., Décréau, P.M.E., Escoubet, C.P., Gustafsson, G., Laakso, H., Lindqvist, P.-A., Lybekk, B., Mozer, F. and Vaivads, A.

Four-point high time resolution information on electron density on Cluster 

Pulkkinen, T.I., Palmroth, M. and Ganushkina, N.Y.

Large-scale magnetospheric modeling and Cluster II observations 

Stasiewicz, K., Khotyaintsev, Y., Gustafsson, G., Lindqvist, P.-A., Mozer, F., Eriksson, A. and Carozzi, T.

Large amplitude Alfven waves at the magnetopause 

Torbert, R.B., Paschmann, G., Quinn, J., Haerendel, G., Mozer, F.S., André, M., Ericsson, A., Gustafsson, G., Vaith, H., Foersten, M., Georgescu, E., Mcilwain, C., Kern, S.S., Fillius, W., Kletzing, C., Briggs, B., Matsui, H., Lindqvist, P.-A. and Pederse

Cluster stormtime electric fields from EDI and EFW 


2001 AGU Spring Meeting, John B. Hynes Convention Center, Boston, Massachusetts, 29 May - 2 June 2001

Bale, S.D., Mozer, F.S., André, M., Ericsson, A.I., Gustafsson, G., Holmgren, G., Lindqvist, P., Holtet, J., Lybekk, B., Pedersen, A., Grard, R., Laakso, H., Mursula., Tanskanen, P. and Yerby, K

Cluster EFW measurements of bow shock thickness, speeds, and normals 

Bale, S.D., Mozer, F.S., André, M., Ericsson, A.I., Gustafsson, G., Holmgren, G., Lindqvist, P., Holtet, J., Lybekk, B., Pedersen, A., Grard, R., Laakso, H., Mursula., Tanskanen, P. and Yerby, K.

The normal, thickness and speed of the dusk magnetopause from Cluster Electric Field and Wave experiment measurements 

McFadden, J. .P., Mozer, F.S., Carlson, C.W., Parks, G., Larson, Bosqued, J.M., Dandouras, I., Reme, H ., Sauvaud, J.A., Balogh, A., Dunlop, M., Décréau, P., Kistler, L., Moebius, E., McCarthy, M., Klecker, B., Bavassano-Cattaneo, M. and Lundin, R.

Cross-calibration and comparison of measurements between the particle and field instruments on Cluster 

Torbert, R.B., Paschmann, G., Quinn, J., Mozer, F.S., Mozer, F.S., Kistler, L..., Mouikis, C., Haerendel, G., Puhl-Quinn, P., André, M., Gustafsson, G., Vaith, H., Foerster, M., Georgescu, E., McIlwain, C., Kerr, S..., Kletzing, C., Matsui, H. ; Lindqvist, P.; Pedersen, A., Fillius, W. 

Inter-comparison of Electric Fields measured by the Electron Drift Instrument(EDI) and the Electric Field and Waves Instrument (EFW ) on the CLUSTER Spacecraft 

Wygant, J. R .; Way, P.; Keiling, A.; Cattell, C. A.; Lysak, R. L.; Temerin, M. A.; Mozer, F. S.; Mende, S.; Parks, G.; Brittnacher, M.; Kletzing, C. A.; Scudder, J. D.; Petersen, W. K.; Russell, C. T.; Spann, J.; André, M.; Toivanen, P.; Lotko, W.; Streltsov, A. 

Spacecraft observations of intense electric and magnetic field fluctuations and associated earthward magnetic field -aligned poynting flux throughout the plasma sheet at 4-6 Re altitudes during major geomagnetic storms 


Sheffield Space Conference: Multipoint Measurements Versus Theory, 24-26 April 2001, Sheffield, UK

André, M. An overview of first results from the electric field and wave investigation on Cluster

Pedersen, A., André, M., Gustafsson, G., Vaivads, A., Bale, S. and Lindqvist, P.A.

Cluster electric field measurements at the magnetopause 

Roux, A., Le Contel, O., Perraut, S., Robert, P., Cornilleau, N., Gustafsson, G., André, M., Eriksson, A.I. and Wahlund, J.E.

Electromagnetic fluctuations measured on board cluster satellites 


Fysikermøtet 2001, 14-17 June, Realfagbygget, NTNU, Trondheim, Norway (2001)

André, M. The Cluster mission: some results and plans related to electric field observations

Pedersen, A.

Cluster observations at the magnetospheric boundaries 


Fourth International Workshop on Nonlinear Waves and Chaos in Space Plasmas, Tromsø, June 17-22, 2001 (2001)

Cattell, C. Observations of high and low altitude solitary waves and comparison to theory

Eriksson, A.

Cluster EFW multipoint magnetosheath wave observations

Kintner, P.

Measurements of solitary electron holes


2001 AGU Fall Meeting, San Francisco,California, 10-14 December (2001)

André, M., Balogh, A., Cornilleau-Wehrlin, N. and Paschmann, G. Electric Field Investigations by Cluster The four Cluster satellites give a unique opportunity to investigate plasma processes in the terrestrial magnetosphere. Here we summarize some recent findings where electric field observations are of major importance. The results include observations of the magnetopause and the auroral region. Both the motion of large scale (thousands of kilometers) structures as well as wave phenomena at smaller spatial scales (ion gyro radius) are compared and discussed.

Angelopoulos, V., Mozer, F.S., André, M. and Lindqvist, P.

Geotail-CLUSTER Correlative Measurements of Plasma Sheet Poynting Flux During the Course of Substorms

Two fortuitous conjunctions between Geotail in the equatorial plasma sheet and CLUSTER at ~4Re altitude on plasma sheet field lines are utilized to study the evolution of Poynting flux from its source to the aurora. Increased wave power at both satellites correlates with increased electrojet and auroral activity. The four Cluster satellites show qualitatively very similar Poynting fluxes and overall wave behavior. The differences between the satellites are being used to characterize the temporal and spatial properties of the observed waves. Of primary interest is the propagation and dissipation of the waves along the field lines, which in turn, depends critically on the perpendicular wavelength and propagation speed. We discuss ionospheric closure via Alfven waves or stationary field aligned currents as revealed by multiple crossings of the same region. We finally explore the possibility of high altitude dissipation (between CLUSTER and Geotail), if perpendicular scale-lengths are already on the ion gyroradius scale size at those altitudes.

Balikhin, M.A., Dunlop, M., S., W., Krasnoselskikh, V., Andre, M., Nozdrachev, M. and Allene, H.

Terrestrial Bow Shock in the Electrostatic Subshock Regime

Scales of the electromagnetic field in the shock front have been estimated using CLUSTER data. The values of these scales has allowed us to identify different classes of collisionless shocks. Based on this identification we have shown that CLUSTER observed the terrestrial bow shock in the electrostatic sub-shock regime, which has been studied theoretically but has only been previously observed in laboratory plasmas. According to our knowledge it has never been identified reliably in space plasma. This regime exists in a narrow parameter range between subcritical shocks and supercritical reflection shocks.

Bates, I., Balikhin, M.A. and André, M.

Wave Mode Identification Using Cluster Data

In two satellite data wave-mode identification is limited by the methods for finding the wave propagation directions (e.g. minimum variance analysis). These methods put strong limitations on the properties of the observed waves. The Cluster-II mission allows the directions to be found without the limitations imposed by MVA. This enables identification of wave modes observed in the electric field components. Such an identification was carried out for low frequency waves observed in the magnetosheath by EFW.

Behlke, R., André,M., Buchert, S., Schwartz, S., Dunlop, M., Lucek, E., Balogh, A. and Mann, G.

Multi-Spacecraft Measurements of the Electric Field of Short Large Amplitude Magnetic Structures (SLAMS)

Short Large Amplitude Magnetic Structures (SLAMS) are observed in the upstream region of the quasi-parallel region of the Earth's bow shock. They seem to grow out of the upstream ULF wave field and associated diffusive ions in the foreshock. While convected with the solar wind, SLAMS decelerate and heat the flow. Thus, the quasi-parallel bow shock region could be considered as a patchwork of SLAMS. We present multi-spacecraft measurements of the electric field in SLAMS and the ULF wave field obtained by CLUSTER with the highest instruments' resolution. The relation between both the ULF waves and SLAMS is studied. Furthermore, the shapes and sizes of SLAMS and their spatial distribution are investigated.

Cattell, C.A., Dombeck, J., Kimkhan, K.H., Wygant, J.R.,  Mozer, F.S., André, M. and Elphic, R.C.

Observations of Solitary Waves and Wave Packets by Cluster

Solitary waves have, for the first time, been identified in the Polar 3d electric field data at the subsolar, equatorial magnetopause. These nonlinear, bipolar electric field pulses parallel to the magnetic field occur both as individual spikes and as trains of spikes. The solitary waves have amplitudes up to 25 mV/m, and velocities from 150 km/s to >2000 km/s, with scale sizes the order of a kilometer (comparable to the Debye length). Almost all the observed solitary waves are positive potential structures with potentials of 0.1 to 5 Volts. They are often associated with very large amplitude waves in either or both the electric and magnetic fields. Although most of the observed signatures are consistent with an electron hole mode, the events with very low velocities and the few negative potential structures may be indicative of a second type of solitary wave in the magnetopause current layer. The solitary waves may be an important source of dissipation and diffusion at the magnetopause.

Cornilleau-Wehrlin, N., Chanteur, G., Perraut, S., Rezeau, L., Robert, P., Roux, A., Sahraoui, F., Belmont, G., Chust, T., Le Contel, O., Maksimovic, M., Hubert, D., Lacombe, C., Lefeuvre, F., Parrot, M., Pincon, J., Décréau, P.M., Harvey, C.C. , Louarn, P., Kofman, W., Santolik, O., Gurnett, D. A., Alleyne, H.S., Gough, M.P., André, M., Gustafsson, G., Pedersen, A., Roth, M., Pellinen, R., Balogh, A.

First Results of the Spatio-Temporal Analysis of Field Fluctuations Experiment (STAFF) of Cluster

STAFF experiment is one of the five experiments which constitute the Cluster Wave Experiment Consortium (WEC). STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, a wave form unit (up to either 10 Hz or 180 Hz) and a spectrum analyzer (up to 4 kHz) (Cornilleau-Wehrlin et al, 1997). The spectrum analyzer combines the 3 magnetic components of the waves with the two electric components measured by EFW to calculate in real time the 5  5 Hermitian cross-spectral matrix at 27 frequencies distributed logarithmically in the frequency range 8 Hz to 4 kHz. The time resolution varies between 0.125s and 4s. Different tools have been prepared (Cornilleau et al., 2000), specific to the Cluster related studies. The first results presented will show the capabilities of the experiment in different key regions of the magnetosphere-solar wind system encountered by Cluster, using different specific tools.

Ericsson, A.I., André, M., Behlke, R., Tjulin, A. and Vaivads, A.

Magnetopause Waves: Cluster ResultsMagnetopause Waves: Cluster Results

Waves and fluctuations are of fundamental interest for understanding transport processes across the magnetopause. The four Cluster spacecraft have provided unprecedented possibilities to study the stability and localization of these processes. We present a study of waves in the 10 Hz frequency range, based on electric field data from the EFW instrument and supported by magnetic data from STAFF and FGM instruments. Our examples show general similarity over the length scale of the satellite separation (500 - 1000 km), with the strongest electric field signatures apparently localized to scales comparable to the ion gyroradius.

Gustafsson, G., Wahlund, J.E., Stasiewicz, K., André, M., Ericsson, A.I., Laakso, H., Mozer, F. , Lindqvist, P. and Pedredersen, A.

Electric Field and Density Observations of Small-Scale Plasma Structures on Cluster

The four-point measurements by Cluster are well adapted to study small-scale plasma structures in the plasma regions of the magnetosphere out to the solar wind. A new probe environment constructed for the Cluster electric field experiment produces electric field and spacecraft potential (density) data of very high quality. The observations used in this study are based on the period when the spacecraft had a separation of about 600 km in the tetrahedron configuration and apogee was on the dayside of the Earth. Data from the four spacecraft show that signatures in the electric field with high coherence are frequently observed for timescales of tens of seconds or longer in many plasma regions along the orbit. Both periodic waveform and solitary structures are observed. The three dimensional characteristics of the various events and their possible sources will be discussed.

Marklund, G.T., Karlsson, T., Ivchenko, N., Lindqvist, P., André, M., Buchert, S., Gustafsson, G. and Vaivads, A.

Auroral Electric Fields Observed by Cluster Near Perigee

Results are presented on auroral electric field structures using Cluster data obtained near perigee, where the four Cluster spacecraft are aligned as pearls on a string. Intense highly structured electric fields are frequently observed on auroral field lines by Cluster during substorm activity. The scale sizes are typically 5-20 km (at the ionospheric level) and field magnitudes up to 150 mV/m are observed. With a time separation of a few minutes between the four satellites the temporal evolution and stability of the structures can be investigated in detail. The stability of the structures is found to depend strongly on the substorm activity level. During oval expansion the structures are very dynamic and change shape and polarity but otherwise the structures can be fairly stable over 100 s.The more stable structures are associated with field-aligned currents and energetic electron transition regions associated with steep gradients in the satellite potential. For the more stable structures it is likely that they represent the high-altitude extension of quasi-stationary auroral potential structures. The Cluster data may further be used to reveal the specific form of the auroral potential structures and their stability.

Masson, A., Moullard, O., Laakso, H., Grard, R., André, M., Decreau, P. and Cornilleau-Wehrlin, N.

2-D MHD turbulence in the vicinity of the plasmapause

The CLUSTER quartet crosses the plasmasphere once per orbit when the geomagnetic activity is not too high. In this case, the plasmasphere may shrink to altitudes below L=4. The plasmapause, the boundary between the plasmasphere and the magnetosphere, is often considered to correspond to a step-like density drop out (around 1000 e-/cc in the plasmasphere and 1 e-/cc outside), which fits to the image of a dense and smooth electron density "doughnut" around the Earth. But, as observed by CLUSTER, the reality is more complex: large density fluctuations are observed inside the plasmasphere or at the plasmapause. We have analyzed these large fluctuations on the Spacecraft Potential, considered as a proxy of the electron density, measured by the Electric Field and Waves instrument. The WHISPER relaxation sounder is used for calibration below 100 e-/cc. A companion presentation on this subject will be made by O. Moullard. We check for the presence of 2-D MHD turbulence. Such turbulence could be produced by velocity shear at the flow separatrix, which can be detected using the electric field data. As a unique feature of CLUSTER, the use of the four satellites facility allows to investigate the spatial extension and the temporal evolution of this turbulence. Finally, the relation between these large amplitude fluctuations and low frequency emissions observed by STAFF are investigated.

Moullard, O., Masson, A., Laakso, H.,  André, M., Cornilleau-Werhlin, N. and Decreau, P.

Plasma waves observed during plasmapause crossings

Different types of plasma waves are observed during plasmapause crossings with the 4 CLUSTER satellites. Using WHISPER, STAFF and EFW data, we investigate the electromagnetic and electrostatic waves with frequency below the electron cyclotron frequency (fce), at fce (10-15 kHz), between harmonics of fce, and at near the plasma frequency (fp, 20-220 kHz). The waves are interpreted with respect to local density structures that have steep density gradients covering up to a few hundreds per cm3. Each of these density enhancements corresponds to an incursion into a plasmaspheric like plasma. Below the WHISPER observation limit, 80 kHz, the plasma density is inferred from the local fp emission and is used to obtain a relationship between spacecraft potential and density. Above 80 kHz, this relationship serves to determine fp from the spacecraft potential. Thus a density measurement is provided in a region where often particle instruments do not operate. Attempts are made to identify and inter-relate the observed waves using multi-point analysis. An interpretation on the density structures and the low frequency electromagnetic waves is also proposed in a companion paper (A. Masson et al.).

Mursula, K., Penttinen, K.,  André, M., Gustafsson, G., Bale, S., Mozer, F. and Cornilleau-Werhlin, N.

Observations of Electromagnetic Ion Cyclotron Waves Onboard the Cluster Satellites

The electric field and wave (EFW) instrument on board the four Cluster satellites samples normally 25 samples of the two spin-plane components of the electric field per second. This covers the whole frequency range of electromagnetic ion cyclotron (EMIC) waves, allowing unique possibilities to study these waves in the different parts of the magnetosphere, magnetosheath and solar wind, and within their boundary layers. Observations at the four Cluster satellites give information about the conditions of EMIC wave generation, the spatial extent of the wave source and its temporal development as well as wave propagation. We will present here examples of EMIC waves observed by the EFW instrument in the different regions and compare the EFW observations with simultaneous waves observed on ground.

Persoon, A., Gurnett, D., Pickett, J., Canu, P., Decreau, P., Laakso, H., Pedersen, A., André, M., Parks, G., Wilber, M., Reme, H., Goldstein, M. and Fazerkerley, A.

Multipoint Plasma Density Measurements from Cluster Wave and Particle Instruments

Measurements from instruments onboard the Cluster spacecraft are used to study regions of diminished plasma density inside and poleward of the nightside auroral zone. The plasma density is derived from the digitization of the electron plasma frequency cutoff of the whistler mode auroral hiss, using the electric field spectrum measurements from the Wideband Plasma Wave Instrument (WBD). Two nightside auroral zone crossings, on May 8 and July 21, 2001, each with simultaneous measurements from two Cluster spacecraft, have been selected for this study. Both of these intervals contain multiple low density structures and provide an opportunity to make multi-instrument comparisons of the WBD electric spectrum measurements with the electron plasma frequency measurements of the WHISPER experiment and the spacecraft potential measurements of the Electric Fields and Waves (EFW) experiment. Since the satellite potential measurements are very sensitive to variations in the electron density, EFW spacecraft potential and density measurements will complement the WBD density measurements in the low density regions. Density variations will also be compared to the observed ion fluxes, using the ion distribution functions of the Cluster Ion Spectrometry (CIS) instruments and the low energy electron fluxes, using the electron velocity and energy distributions of the Electron and Current Experiment (PEACE).

Roux, A.F., Fontaine, D., Le Contel, O., Perraut, S., Robert, P., Cornilleau-Wehrlin, N., Sauvaud, J.A., Reme, H.,  André, M. and Balogh, A.

Multipoint and Multi-instrument Study of a Flux Transfer Event Crossing: Preliminary Results

Data from several instruments on Cluster (PEACE, CIS, EFW, FGM and STAFF) are used to investigate the transient interaction between the solar wind and the Earth's magnetic field. We study the crossing of an isolated FTE (January 26th, 2001, around 11:31 UT), presumably detached from the magnetopause. As the FTE is crossed (i) the modulus of the ion flow velocity (from CIS) is found to increase by about a factor 2, and its direction also changes. The ion flow is more or less anti-parallel to the magnetic field, and parallel to the current density (as determined from its magnetic signatures on the FGM experiments aboard the 4-Cluster spacecraft), at the edges of the FTE. Data from PEACE give evidence for enhanced electron fluxes, in particular in the directions parallel and anti-parallel to B. However the enhancement in the flux of relatively energetic electrons (> 1 keV) lasts much longer than that of electrons parallel to B, which suggests an escape from the magnetosphere. Conversely, when field aligned electric currents are measured the flux of medium energy electrons (about 100 eV) tends to be larger for electrons flowing along the magnetic field, than for electrons anti-parallel to B. This suggests that magnetosheath electrons flow earthward, inside the FTE. Waves observed on STAFF and EFW are shown to heat the electrons preferentially along the magnetic field, thereby explaining why enhanced fluxes of electrons, parallel and antiparallel to B are observed.

Torbert, R.B., Paschmann, G., Quinn, J., Baumjohaan, W., Mozer, F.S., Kistler, L., Mouikis, C., Puhl-Quinn, P., Andre, M., Kletzing, C.A. and Lindquist, P.- .

Three-Dimensional Electric Field Measurements at the Plasma Sheet Boundary as measured by the Electron Drift Instrument (EDI) and the Electric Field and Waves Instrument ( EFW ) on the CLUSTER Spacecraft

On CLUSTER, three dimensional electric fields, including the component parallel to B, can be measured by combining the information from the double-probe (EFW) , and those of the Electron Drift Instrument (EDI). EFW measures the potential difference between spherical probes spinning in a plane, and computes the two components of the field in that spin plane. EDI measures the drift-step vector, which is the displacement of electron orbits after one gyro-period, and computes the two components of the field in the plane perpendicular to the magnetic field. Comparison of the field along the axis which is common to these two planes, shows very good agreement in many plasma regions. We will show data from the night-time plasma sheet where large fields are sometimes observed near the boundaries and particle populations make rapid changes. These fields show a complex spatial and temporal structure that appears to be neither constant in time nor space.

Wygant, J., Way, P., Keiling, A., Cattell, C.A., Lysak, R.L., Lysak, R.L., Mozer, F.S., Mende, S., Frey, A., Kletzing, C.A., Scudder, J.D., André, M. and Elphic, R.C.

Observations of Intense Electric and Magnetic Fields and Associated Poynting Flux Through-Out the Plasma Sheet During Major Geomagnetic Storms

We present observations from the EFI and MFE instruments on the Polar spacecraft obtained during several major geomagnetic storms (Dst < -100 nT)of intense electric field (> 40 mV/m, ptp) and magnetic field fluctuations (40-80 nT, ptp). . These spatially extensive field wave fields are observed at altitudes of 4-6 Re and last for 10-30 minutes in the spacecraft frame and can exist over a large fraction of the spatial extent of the plasma sheet. The fields map to a latitudinal extent on the ground of 4-6 degrees. This is a much larger spatial extent than the previously reported observations of intense Poynting flux due to Alfven wave at the outer boundary of the plasma sheet which were observed to last in the spacecraft frame a period of about 3 minutes and occurred during the expansion phase of substorms. The Poynting flux associated with the fields presented herein is directed along the magnetic field direction towards the Earth and exceeds 0.25 erg/cm^2 s. If mapped to 100 km altitude along converging magnetic field lines, the Poynting flux peak values can exceed 30 ergs/cm^2 s. This is sufficient to power some of the most intense aurora in the UVI data set. Preliminary analysis indicates that the ratio of E/B for these waves is consistent with a mixture of Alfvenic fluctuations interspersed with steady state electric fields closing in the ionosphere through field aligned currents. We will compare these observations of intense Poynting flux to simultaneously obtained images of the aurora obtained from Polar and IMAGE spacecraft Ultravioltet Imagers and the associated estimates of the electron energy flux . The data from the four Cluster spacecraft will be analyzed to provide estimates of the spatial scale sizes of the waves from similar kinds of events.



EGS XXVII General Assembly, Nice (2002)

André, M. et al

Multi-Spacecraft Observations of Thin Layers at the Magnetopause (invited)

Backrud, M., André, M., Buchert, S., Olsson, A., Vaivads, A., Wahlund, J-E., Balogh, A., Cornilleau-Wehrlin, N., Fazakerley, A., Reme, H.

Cluster observations of broadband waves in the auroral zone

Behlke, R., André, M., Vaivads, A., Eriksson, A.I., Buchert, S., Lucek, E., Balogh, A., Bale, S., Mann, G., Schwartz, S.J.

Short Large Amplitude Magnetic Structures (SLAMS) are observed in the upstream region of the quasi-parallel region of the Earth´s bow shock

Morooka, M. et al

Dayside High Latitude Auroral Particle Acceleration Observed by the Cluster Satellites

Stenberg, G. et al

Multi-satellite observations of the wavevector of whistler waves near the magnetopause

Sundkvist, D., André, M., Cornilleau-Wehrlin, N., Dunlop, M., Vaivads, A., Wahlund, J-E.

Cluster II observations of broadband ELF emissions and energy transport in the polar cusp

Tjulin, A.

The simple-pole distribution function for a magnetized plasma

Vaivads, A.

Cluster Auroral Team, The auroral field-aligned acceleration -Cluster results (invited)


URSI XXVII General Assembly, Maastricht, The Netherlands (2002)

André, M. et al

Multi-Spacecraft Observations of Thin Layers at the Magnetopause (invited)

Gustafsson, V., André, M., Wahlund, L-E., Vaivads, A., Stasiewicz, K

Electric field measurements of low frequency waves on Cluster


AGU Fall Meeting, San Fransisco (2002)

André, M. et al

The Magnetopause at Ion and Electron Scales

Vaivads, A., André, M., Sundkvist, D, Wahlund, J-E., Buchert, S., Fazakerley, A., Savaud J. Cornilleau-Werlin, N.

Small Scale Magnetopause - Cluster Interferometric Measurements


IRF-days, Kiruna Sept 3, 2002

Sundkvist, D.

Cluster Observations of Broadband Extremely Low Frequency Emissionbs and Energy Transport in the Cusp (oral presentation)


Astrobiology Conference, Graz, 16-18 Sept

Wahlund, J-E. et al

Possible Swedish Astrobiology Missions to Venus


Cluster Workshop, RAL, UK, 2002/09/18-20

Cully, C.M., Donovan, E.F., Buchert, S. et al

Magnetic Reconnection Near Substorm Onset: Multipoint In-situ Observations

Morooka, M. et al

On the Pulsation phenomena above the dayside auroral region