Spatial and temporal variations of total electron content (TEC) and outgoing longwave radiation (OLR) during the period of greater earthquakes near the Indian subcontinent

Abstract

This paper purports the temporal and spatial variations of total electron content (TEC), outgoing longwave radiation (OLR) and sea surface temperature during the greater earthquake regime. Nighttime TEC variations have been observed to be lower than those of the daytime. They were in the range of 10–30 TECU (µ = 16 TECU) over nighttime, whereas 12–40 TECU (µ = 26 TECU) during daytime. The coefficient of variation (CV) is of 32 % during the daytime and 51 % over the nighttime by using the IRI-2012 model (as per the boundary condition and grid-level output during event period). Latitude and longitudinal variations of TEC values integrated over the preparatory zone with in 5-h limits are in the range of 8–48 TECU (µ = 30 TECU, CV = 45 %) and 14–48 TECU (µ = 28 TECU, CV = 37 %). Mapping for the 2 days anomalies of OLR have good influence with the effect of greater earthquake; except the three events, it has increased from 20 to 100 watts/m2. The detailed synthesis of this paper has showered light on the necessity of spatial variation of the TEC apart from temporal variations.