Climatology of ionosphere over Nepal based on GPS TEC data from 2008 to 2018

Abstract. In this study, we analyze the climatology of ionosphere over Nepal based on GPS derived VTEC observed from four stations: KKN4 (27.80° N, 85.27° E), GRHI (27.95° N, 82.49° E), JMSM (28.80° N, 83.74° E), DLPA (28.98° N,82.81° E) during years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations of VTEC during all time of solar cycle 24. The results clearly revel the presence of equinoctial asymmetry in TEC which is more pronounced in maximum phases of solar cycle in year 2014 at KKN4 station followed by descending, ascending and minimum phases. Diurnal variation of VTEC showed short-lived day minimum which occurs between 5:00 to 6:00 LT at all the stations considered with diurnal peak between around 12:00 to 15:00 LT. The maximum value of TEC is observed during spring equinox than autumn equinox with a few anomalies. Similarly, winter anomalies are noticed during increasing and maximum phases of the solar cycle2011 and 2014 from almost all stations taken in the study.