  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.
