Relationship between TTI and Various Thunderstorm Related Parameters over Kerala, India

This study mainly focuses on the relationship between Total Totals index (TTI) and other thunderstorm related parameters over Kerala region, India. This study has been carried out on thunderstorm days for the pre-monsoon season during the time period 2017–2022. The thunderstorm related parameters such as lightning, K Index (KI), Humidity Index (HI), Total precipitable water (TPW), Rainfall to Lightning Ratio (RLR), Maximum updraft speed (MUS), Lifted Index (LI), Convective available potential energy (CAPE), Dew point depression (DPD), Cloud fraction (CF) and Temperature Difference (TempDiff) have been considered for the analysis. For a better understanding between TTI and thunderstorm indices, two distinct regions D1 (10.8°-12.4° N, 75.2°-76.8° E) and D2 (9.2°-10.8° N, 76.2°-77.8° E) of Kerala state were selected as the study region. The results reveal that D2 region (135 days) showed more lightning activity than D1 region (88 days). A significant positive trend has been seen between TTI and KI parameters. RLR & TPW parameters showed a significant negative trend with TTI parameter. MUS exhibits positive trend whereas LI showed negative trends with TTI on lightning days over both regions. This study also shows that the CAPE and DPD showed an increasing trend with TTI during lightning days. We also utilized Random forest technique to study the relationship between various thunderstorm related parameters.