Average terrestrial ring current derived from AMPTE/CCE‐CHEM measurements

The present study attempts to analyze the average ring current density and pressure in the magnetospheric equatorial plane (as a function of geocentric distance and local time) based on the AMPTE/CCE‐CHEM proton distributions according to two different AE ranges, corresponding to a low ( AE <100 nT) and a moderate (100 nT< AE <600 nT) geomagnetic or auroral activity. In order to obtain a statistically significant database for a high spatial resolution, the data were averaged over 2 years. The results provide a trend of the ring current and show its general average features as a function of geomagnetic activity. In particular, the total ring current is dominated by the pressure gradient term, resulting in an eastward current in the inner magnetosphere ( L <4.5) and an extended westward current at higher altitudes. The westward current is always stronger than the eastward current. Moreover, the ring current system is a function of magnetic local time, exhibiting a noon‐midnight asymmetry in general, as well as a function of geomagnetic activity exhibiting an enhancement of about 20% during active times (in midnight‐dusk region only). The location of the total current peak in the midnight sector is at about MLT=2300, and its changes with magnetic activity are interpreted as an effect of the particles injection from the tail during the storms/substorms. The derived current values are compared to previous model predictions and observations.