Ionosphere TEC variations over Bosnia and herzegovina using GNSS data

Abstract

Total Electron Content (TEC) is the key parameter for studying ionosphere and corrections of ionspheric effects on positioning by Global Navigation Satellite Systems (GNSS). TEC variability using GNSS observation data of SRJV station from Sarajevo was analyzed, for the period January 2014–May 2015. Resulting day to day and seasonal variations show expected behavior. Special attention was paid to the analysis of TEC variations during the weeks before and after the earthquakes, that are registered by Federal Hydro-Meteorological Institute in Sarajevo, in February and April 2015, with epicenters located near Sarajevo. Magnitudes of earthquakes were M ~ 4 Richter, lower than the threshold for detection ionospheric earthquake precursors (M ~ 5). For analysis of TEC variations during seismic activities, GNSS observation data of ZADA station for February–April 2015 were used as well. Deviations from 15 day median values of TEC within weeks around these seismic activities were higher than 10 TEC units. A closer examination of the data showed that the anomalies were caused by gap in data and space weather conditions, but the rest of the anomalies are yet to be linked to seismic activities mentioned.