Radial distribution of the inner magnetosphere plasma pressure using low-altitude satellite data during geomagnetic storm: the March 1-8, 1982 Event

Plasma pressure distribution in the inner magnetosphere is one of the key parameters for understanding the main magnetospheric processes including geomagnetic storms and substorms. However, the pressure profiles obtained from in-situ particle measurements by the high-altitude satellites do not allow tracking the pressure variations related to the storms and substorms, because a time interval needed to do this generally exceeds the characteristic times of them. On contrary, fast movement of low-altitude satellites makes it possible to retrieve quasi-instantaneous profiles of plasma pressure along the satellite trajectory, using the fluxes of precipitating particles. For this study, we used the Aureol-3 satellite data for plasma pressure estimation, and the IGRF, Tsyganenko 2001 and Tsyganenko 2004 storm time geomagnetic field models for the pressure mapping into the equatorial plane. It was found that during quiet geomagnetic condition the radial pressure profiles obtained coincide with the profiles, obtained previously from the high-altitude measurements. On the contrary, it was found that during geomagnetic storm the plasma pressure profiles became sharper; the position of the maximum of plasma pressure corresponds to expected one for given Dst minimum; the maximum value of inner magnetosphere static pressure correlates with the solar wind dynamic pressure. Increase in the plasma pressure profiles indicates the possibility to consider the interchange instability as one of important factors for the development of the main phase of geomagnetic storm.Comment: Accepted in Advances in Space Researc

Space and ground-based investigations of dayside reconnection: Cluster, double star and SuperDARN observations

In this paper, we present an overview of several investigations that have exploited Cluster, Double Star and SuperDARN radar data in order to scrutinise the coupling of the solar wind, magnetosphere and ionosphere. The studies introduced have drawn upon simultaneous space- and ground-based data in order to overcome the inherent shortcomings of the in situ (space-based) and remotely-sensed (ground-based) measurement techniques. In particular, we shall highlight the results of studies that investigate the dynamics arising from magnetic reconnection at the dayside magnetopause and the resulting ionospheric responses

Statistical study of the electron-only mid-altitude cleft region: Cluster observations

The Cluster spacecraft have now amassed 3 years of data from crossings of the mid-altitude cleft/cusp.Comparison of particle data from the PEACE and CIS instruments shows that there is pronounceable difference in latitude between the equatorward edges of the electron and ion populations of the cleft region, and this difference increases in the dawn/dusk directions. We define the electron edge of the cleft by the first injection of the magnetosheath-like electrons and the disappearance of the trapped plasma-sheet particles.Correspondingly the ion boundary is identified by the first injection of magnetosheath-like ions. The region between these two boundaries, which we define as the 'electron-only' cleft region, contains parallel and/or antiparallel electron beams. This region is co-located with sharp enhancements of the wave activity and with transverse heating and outflow of ionospheric ions. We present a statistical study of the plasma properties of the electron-only region, including an estimation of the electron anisotropy, density and velocity. We estimate the latitudinal size of this region as a function of magnetic local time (MLT) and the interplanetary magnetic field (IMF) conditions. Moreover, using time differences between the first injection of the electrons and ions in the mid-altitude cusp, we infer a distance along the field lines to the reconnection site on the magnetopause

Correction to ‘‘ULF wave identification in the magnetosheath: The k-filtering technique applied to Cluster II data’’

There is an error in the matrix transformation from the GSE frame to the MFA (Magnetic Field-Aligned) on

Correlation between suprathermal electron bursts, broadband extremely low frequency waves, and local ion heating in the midaltitude cleft//low-latitude boundary layer observed by Cluster

The Cluster spacecraft often cross the midaltitude cleft/cusp and observe a very well defined “electron-only cleft” region consisting of electron injections without magnetosheath ions. This region contains soft suprathermal (<500 eV) electron bursts in antifield and/or field-aligned directions. We present an example of such observations which shows that the O+ ion outflow at midaltitudes appears just poleward of the open-closed boundary simultaneously with electron injections and was observed in the cleft, cusp, and mantle in the form of narrow energy beam. Inside the “electron-only” cleft the suprathermal electron bursts are strongly correlated with strong O+ and H+ ion heating and with localized extra low frequency (ELF) (1–10 Hz) magnetic field wave power with broadband spectra. Our study shows that strong ion heating was observed only in the region with electron field-aligned anisotropy more than 2. In addition, comparison of particle data from two spacecraft, which crossed the heating region with a time difference of 4 min, shows the correlation between ion outflow fluxes and fluxes of the injected electrons. Whereas ELF electromagnetic waves are localized inside the ion heating region, ELF electrostatic waves are detected throughout the cleft/cusp/mantle regions, where strong ion heating was not observed, suggesting that electromagnetic ELF waves heat ions in the cleft region. Owing to the absence of magnetosheath ions and strong field-aligned currents, we suppose that inside “electron-only” cleft region the suprathermal electron bursts are most likely an energy source for the wave destabilization. We suggest that the location of the heating region and the level of the outflow ion fluxes could be related to electron injection in the cleft in such events