Quiet time response of ionosphere over Nepal

Abstract

This study attempts to characterize the ionospheric behavior over Nepal during quiet periods by studying ionospheric total electron content in 2009 and 2014 utilizing ground-based GPS data from the station GRHI (Gorahi).  The GPS receiver and satellite pseudorange measurement is used to compute the VTEC.  Our study shows in the quietest day of January 12, 2009, at the minimum time of solar cycle 24, and January 19, 2014, during the highest phase of solar cycle, a flat curve with a slight peak in the diurnal TEC of around 12 and 28 TECU. In 2009, there was no equinoctial asymmetry; nevertheless, in 2014, spring VTEC was higher than autumn VTEC. The plot reveals the highest VTEC in 2009 was between 10 and 30 TECU, and it spreads roughly from 7.75 to 18.75 LT. In 2014, the maximum VTEC was between 20 and 120 TECU, and it spreads from 8.75 to 17.90 LT.  Spring had the highest value and winter the lowest in 2009, but, in 2014 summer had the lowest value and spring the highest value of TEC. The results of this study advance our understanding of ionospheric physics and offer important new perspectives on the evolution of the ionospheric layer over Nepal and other comparable regions.