Spatial Variability of Sensible and Latent Heat Fluxes with Convective Thermodynamic Indices over East India during Pre-Monsoon Season

Abstract

This study investigates the spatial variation of surface sensible heat flux (SHF) and surface latent heat flux (LHF), along with the Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CIN), during the pre-monsoon season over east India (states of Odisha, West Bengal, and Jharkhand) for 2001–2021. The results reveal that at 0900 UTC, the mean values of upward SHF increase over the inland regions in the interior parts of east India, ranging from approximately 250 to 300 W/m². At 2100 UTC, parts of Odisha experience upward SHF, ranging from approximately 1 W/m² to 5 W/m², and rest of the study area experiences downward SHF. The LHF variability shows upwards values during the daytime, and very low values during the nighttime, with coastal regions exhibiting upward LHF values, ranging from 10 to 50 W/m². Mann-Kendall trend (MKT) analysis indicates that at 0900 UTC, southwest and northeast parts of east India show high positive trend values for SHF, approximately 2–6 W/m² per season/year. LHF exhibits a high positive trend in only a few parts of Jharkhand and West Bengal, with a similar range. At 2100 UTC, lower SHF values are present over the interior regions, displaying mixed trend patterns ranging between -0.2 and 0.2 W/m² per season/year. SHF–CAPE demonstrates higher positive correlation values, ranging between 0.4 and 0.6 at 0900 UTC in many regions of the study area. In contrast, nearly all regions exhibit a negative correlation at 2100 UTC, with values ranging from 0.2 to 0.4. Inland regions exhibit a positive correlation for SHF–CIN at 0900 UTC, ranging from 0.5 to 0.1, with lower values for 2100 UTC. The LHF correlations with CAPE and CIN are not significant for the study region.