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

TL;DR

This study uses low-altitude satellite data to analyze the radial plasma pressure distribution in the inner magnetosphere during geomagnetic storms, revealing sharper profiles and correlations with solar wind conditions.

Contribution

It introduces a method to derive quasi-instantaneous plasma pressure profiles during storms using low-altitude satellite flux measurements and geomagnetic field models.

Findings

Pressure profiles become sharper during storms.

Maximum plasma pressure correlates with Dst minimum.

Profiles indicate interchange instability during main storm phase.

Abstract

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.