Modeling of GPS-TEC using QR-decomposition over the low latitude sector during disturbed geomagnetic conditions

Abstract

Given the continuous operation of satellite-based navigation applications, modeling of Total Electron Content (TEC) during magnetic disturbed periods is a significant challenge. The Global Positioning System (GPS)-TEC observations of the Bangalore station (13.02°N, 77.57°E) has been considered and covers the period (2009–2016) of the solar cycle 24. The study emphases on the analysis of TEC variations in eight geomagnetic storms of different intensity: (−223 nT < Dst < −80 nT). The QR decomposition is computed using the Gram-Schmidt (GS) process and is based on observational data from low latitude sectors. For interpolation, the QR model was evaluated on storms that occurred during different periods of solar activity (2009–2016), while for extrapolation the assessment was conducted for the intense storm of March 17, 2015 (St. Patrick's Day storm: Dst −223 nT) in different latitudes, covering the Asian sector between 10°N and 26°N. The R1 and Q1 modes patterns are consistent with changes in the solar proxy index (F10.7) and with regular daily variations and the correlation coefficient is 0.80 and 0.99. The post-residue between the QR model TEC and the GPS- TEC values is ±3 TECU. The QR model captured the TEC responses in consecutive storm cases (18–24, February 2014).The spatial variation of the TEC deviations increases as it moves towards the Equatorial Ionization Anomaly (EIA) crest from the magnetic equator and decreases beyond the crest. The proposed work could be useful for the further study of the Global Navigation Satellite System (GNSS) performance during geomagnetic magnetic disturbed periods.