Disturbances at F2-region heights of equatorial anomaly during geomagnetic storms

Abstract

Neutral gas composition and ionospheric measurements taken by the Dynamic Explorer 2 satellite at F2-region heights during two geomagnetic storms are used to analyze the role of some possible physical mechanisms responsible for the changes of electron density at equatorial and low geomagnetic latitudes. The storms considered occurred on October 2, 1981 (storm 1) and July 13, 1982 (storm 2). During storm 1 (weak), vertical plasma drifts and equatorward storm-time winds operated increasing of the electron density at the trough of equatorial anomaly and the decreases at the crest region. During storm 2 (intense) changes of composition (increase of molecular nitrogen and atomic oxygen) played a fundamental role for the changes of electron density observed at low latitudes in summer hemisphere. It is concluded that different physical processes seem to have varying degrees of importance depending on the intensity of the storm.