GPS-TEC variations during low solar activity period (2007–2009) at Indian low latitude stations

Abstract

The paper is based on the ionospheric variations in terms of vertical total electron content (VTEC) for the low solar activity period from

Whistlers detected and analyzed by Automatic Whistler Detector (AWD) at low latitude Indian stations

“…Using the formula 3.5 in Park (1972) . This is in good agreement with ionospheric total electron contents (TEC) measured using Global Positioning Systems (GPS) based measurements over Indian low latitude stations (Chauhan and Singh, 2010;Kumar et al, 2012). Kumar et al (2012) reported that TEC over low latitude Indian stations varies between 10 TECU and 50 TECU.…”

“…This is in good agreement with ionospheric total electron contents (TEC) measured using Global Positioning Systems (GPS) based measurements over Indian low latitude stations (Chauhan and Singh, 2010;Kumar et al, 2012). Kumar et al (2012) reported that TEC over low latitude Indian stations varies between 10 TECU and 50 TECU. The International Reference Ionosphere (IRI) modeled TEC over Indian stations also compares well with our computed columnar ionospheric electron contents using observed whistlers (Chauhan and Singh, 2010;Kumar et al, 2012).…”

“…Kumar and Singh (2009) using GPS based measurements showed that Varanasi is situated at the edge to equatorial ionization anomaly region. We have also checked our GPS scintillation data for any possibility of observation of some ionospheric irregularities or plasma bubbles and found that some weak ionospheric irregularities were present at the time The ionospheric and other parameters derived from whistler measurements compare well with direct rocket and satellite measurements (Park et al, 1978;Singh et al, 1998;Chauhan and Singh, 2010;Kumar et al, 2012). The study of the latitudinal and longitudinal distribution of ionospheric parameters and its long term variations using rockets and satellites is financially and technically challenging, whereas these can be studied very readily by the whistler technique at a number of stations spread in latitude and longitude.…”

“…Kumar et al (2012) reported that TEC over low latitude Indian stations varies between 10 TECU and 50 TECU. The International Reference Ionosphere (IRI) modeled TEC over Indian stations also compares well with our computed columnar ionospheric electron contents using observed whistlers (Chauhan and Singh, 2010;Kumar et al, 2012). The analysis of whistlers recorded at a ground station yields information about the duct properties through which it has propagated.…”

Impacts of solar activity on performance of the IRI-2012 model predictions from low to mid latitudes

“…The ionosphere, being a complex physical system, exhibits different features like diurnal, seasonal, and spatial variability. The distribution and characteristics of TEC over low, mid, and high latitudes have been investigated by several authors (Rama Rao et al 2006;Yizengaw et al 2007;Liu et al 2008;Bagiya et al 2009;Jain et al 2011;Zou et al 2011;Sojka et al 2012;Kumar et al 2012). The latitudinal variation of the TEC is mostly dictated by the phenomenon of EIA (Kumar and Singh 2009;Venkatesh et al 2011).…”