Variation of the 0+ ion density during low and high solar activity as measured by the SR0SS-C2 satellite

ANANNA BARDHAN, DINESH KUMAR SHARMA, SARVESH KUMAR, JAGDISH RAI

Abstract

The O+ ion density measured by the SROSS-C2 satellite during solar minima (year 1995, F10.7 = 77) and maxima (year 2000, F10.7 = 181) has been analyzed for studying diurnal, seasonal, latitudinal and geomagnetic variations. The study region covers an area encompassed between 5-35º N latitude and 65-95º E longitude over India at a ~500 km altitude (F2 region). The year 2000 shows significant enhancement in the annual average of O+ ion density and attainment of post sunset secondary enhancement compared to 1995. Attributed to photoionization, daytime shows a maximum ionization compared to nigttime. However, attainment of post sunset secondary maxima is attributed to the strong pre-reversal enhancement in the vertical E × B drift. The effect of geomagnetic activity Kp through the E × B drift dynamic movement on O+ ion density distribution studies indicates periodicities of seven and nine days in 1995 and 2000, respectively, and polynomial dependencyof the O+ ion density on geomagnetic activity Kp. Further on, stratification of the O+ ion density accordingto latitude (5-35º N) indicates high density in mid-latitudes (12-24º N) compared to high and low latitudes,except in the winter of 1995, which shows a distinct trend (i.e., density decreases with increasing latitude).

Keywords

F2 region; O+ ion density; pre-reversal enhancement; E × B drift: geomagnetic activity (Kp); solar minima and maxima.

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