Thermosphere-ionosphere disturbances during two intense geomagnetic storms

Abstract

Neutral gas composition data (molecular nitrogen N , atomic oxygen O and argon Ar) from the Dynamic Explorer 2 satel- 2 lite, and critical frequency of F2-layer obtained with ionosondes, are used to examine the response of the ionosphere-thermo- sphere system during two intense geomagnetic storms on July 13, 1982 and September 21, 1982. After the initial phase of the storms large fluctuations of O density at high and low latitudes and increases of N and Ar densities are produced. Increases of N /O ratio and negative ionospheric storms are correlated and the composition changes are produced by a storm-time circulation.
It is concluded that the behavior of the ionosphere is strongly compositionally controlled at high and low latitudes a few hours after storm commencement.