Dynamic Process Surpasses the Thermodynamic Process in Driving Precipitation Extremes over India

The recent increase in precipitation extremes has attracted immense attention, but the mechanisms are still inadequately comprehended. The primary focus of most studies is on the horizontal advection component of the atmospheric water budget. The present study attempts to comprehend the vertical advection component of the processes over India by decomposing it into dynamic and thermodynamic contributions using the framework proposed by Oueslati et al. (2019), which is often discounted in most of the studies, especially over India. The dynamic contribution is associated with the vertical atmospheric motion, whereas the thermodynamic contribution is associated with the changes in moisture content in the atmosphere. Considering two recent events on the north (Uttarakhand) and the south (Kerala) of the country, the study shows that when compared with horizontal advection component the vertical advection component contributes significantly to the extreme events. Further disintegration of the vertical advection component shows that the thermodynamic contribution is negligible and the dynamic contribution is the vital contributor in these extreme events. To extend the study to all over India, extreme precipitation events are defined using a threshold method, and the results are consistent with the previously considered events. In addition, CMIP6 climate models were used to evaluate the contributions in extreme precipitation events, and the results are remarkably in accord with the findings. This study provides a crucial contribution to the proper prediction of precipitation extremes, which is vital to climate mitigation and adaptation.