Effects of Magnetic & Sunspot Activities on the Topside Ionosphere

Abstract

Results of a study of the scale heights and transition levels in the scale height for magnetically quiet and disturbed conditions for the years 1962-E4 for the latitude range 40-70^ᵒN (geomag.lat.) during the interval 1400-1600 hrs LMT are presented. The scale heights and transition levels are evaluated from the plots of In<i>N </i> versus <i>h </i> obtained using Alouette-I data. Occasionally, these plots drawn for quiet and disturbed conditions show transition from negative changes in electron densities at low altitudes to positive changes in electron densities at high altitudes. From a study of the latitudinal variations of <i>H_D/H_Q </i>in the height ranges 300-500 and 800-1000 km it is found that this ratio increases with increase of latitude in all the sunspot epochs considered from 40 to 60^ᵒN. The latitudinal variations of the transition level in the scale height shows a peak around 55-60^ᵒN, i.e. around the trough in all the years during disturbed days only. The latitudinal variation of (<i>h_m</i>F₂) <i>_D-</i> (<i>h_m</i>F₂<i>)_Q </i> shows a peak, which gradually shifts to lower latitudes with the increase of sunspot number.