Theoretical calculations on the changes in the ionospheric composition and temperature profiles during storms

Abstract

The changes in the ionospheric composition and temperature profiles, in the altitude range of 120–1000 km, due to different mechanisms currently considered important during storms, are estimated quantitatively for a low latitude station, Delhi, for moderate solar activity conditions using the computer method of Stubbe. The theoretical results reported here are discussed in the light of the available ion composition and temperature variations observed at low latitudes during storms with satellite data in the topside ionosphere. The results are presented for the three atomic ions O +, H + and He + which are important in the F-region and topside ionsophere. It is found that all the three atomic ions increase or decrease in phase with the change in the concentration of n(O) when there is no change in total neutral density. When the change in the exospheric temperature T ∞ with its consequent change in neutral composition and an additional storm time increase in N 2 by a factor of 2 is considered, O + is found to increase in the topside and decrease in the bottomside ionosphere, whereas H + and He + decrease all throughout except for a small increase in He + above 800 km during day. The effect of eastward electric field or southward (equatorward) winds during the day is to increase all three ions in the topside ionosphere and to decrease them in the bottomside ionosphere and vice versa for westward fields or northward (poleward) winds. At night, O + shows the same type of behaviour as for day, while He + shows an increase above 900 km and a decrease below that height for eastward fields or soutward winds and H + shows an oscillating behaviour. Electron and ion temperature ( T e and T i ) during the day shows anticorrelation with the change in the electron concentration N e (equal to total ion concentration), whereas at night it does not show any significant change except for the case of change in T ∞ and N 2.