The role of the Arabian Sea (AS) warming on the Indian summer monsoon rainfall is investigated using regional climate model‐Regional Climate Model version 4.7 of International Centre for Theoretical Physics. The model realistically simulates the rainfall, temperature, low‐level winds and vertically integrated moisture flux over the Indian region during the years 2006–2015. It is found that the AS warming decreases the rainfall over most parts of the India, which is mainly due to decrease in the convective precipitation over these regions. The AS warming reduces the magnitude of westerly winds in the southern Bay of Bengal and AS; enhances the moisture convergence over the AS; and causes the prohibition of the moisture‐laden winds from the AS to reach to the Indian land regions resulting into decreased precipitation. The effect of anti‐cyclonic circulation produced over the central India as a result of the AS warming is to further reduce the monsoon rainfall. It is also shown that the AS warming increases the extreme rainfall over most parts of India.

An effort is made to investigate the tropical cyclone (TC) variability over the Bay of Bengal in the warming climate scenario during the satellite era (1979–2018). In this study, the authors investigate interannual variations in the overall capacity of the Bay of Bengal (BoB) basin in the post‐monsoon season to produce either intense or moderate TCs. Globally accepted and widely used metrics accumulated cyclone energy (ACE) and power dissipation index (PDI) are used to examine the energy and damage generated by TCs. A statistical change‐point analysis is conducted to detect the shift in the tropical cyclone frequency and ACE during the study period, indicating the year 1999 as a change point. The results show the increasing trend in ACE in the BoB during the post‐monsoon season with a statistical significance of 95%. On the contrary, the overall frequency is almost unchanged but has shown an increasing trend in the last decade of the study period. Additionally, atmospheric and ocean factors influencing the TC intensity are investigated by applying principal component analysis for three categories of TCs, viz. the very severe cyclonic storm, severe cyclonic storm, and cyclonic storm. Implementation of principal component analysis and correlations of maximum sustained wind speed (MSW²; intensity) with relative vorticity, minimum sea‐level pressure (MSLP), sea‐surface temperature (SST), specific rainwater content, and vertical wind shear revealed relative vorticity as the most dominating parameter amongst all governing factors which determine the final intensity of the BoB TCs. On the contrary, SST shows the different nature of the relationship with different TC categories.

This study examines different precipitation events (PEs) for 1951–2015 using 0.25°×0.25° India Meteorological Department data and diagnoses their associated dynamical and thermodynamical processes during the summer monsoon season over India using ERA5 reanalysis. Our results reveal a significant decreasing trend of mean precipitation, rain event days, light rain events and moderate rain events (MREs) for the overall period. However, the frequency of heavy rain events (HREs) and very heavy rain events (VhREs) has increased. Pettit's test for all PEs and mean precipitation indicates the changes nearly in the 1970s. In spite of this, the rate of change of LREs, MREs and HREs was increased by 17, 91 and 114% after the observed change point with respect to before change point, while for VhREs, this was reduced by 50%. These decreasing (increasing) trends of LREs (VhREs) are attributed to both thermodynamical and dynamical conditions. LREs are driven mainly by convective precipitation having a contribution of ~79%, whereas large‐scale precipitation contributes ~56% to the VhREs. It is observed that the dynamical (thermodynamical) effect largely drives VhREs (LREs) PEs. During VhREs, stronger moisture‐laden low‐level jet (LLJ) from the surrounding ocean converges over the Indian land mass, facilitating favourable conditions for enhanced precipitation. Simultaneously, weaker convective available potential energy (CAPE) during the VhREs underlines inconstancy in thermodynamics. Stronger LLJ and weaker CAPE during the extremes and vice versa for LREs highlight the dominance of the dynamical (thermodynamical) effect during the VhREs (LREs).

The Mediterranean Sea is a relatively small basin with complex, unique topography and has long been considered a hot spot for cyclones. This sea is also characterized by intense mesoscale eddy activity. Although eddies are known to play important roles in cyclones in other regions, their effects on Mediterranean cyclones have not received much research attention. Here, we analyzed how warm‐core eddies (WCEs) and cold‐core eddies (CCEs) interact with Mediterranean cyclones. We considered eight Mediterranean cyclones: four that passed over WCEs and four that passed over CCEs. In general, we observed sudden drops in Mean Sea level (MSL) pressure and increased wind speeds over the WCEs and increased MSL pressure and decreased wind speeds above the CCEs. The temperature of the mixed layer decreased after a cyclone passed over an eddy, but this occurred to a lesser extent for CCEs. In contrast, mixed‐layer salinity decreased in the case of WCEs and increased in the case of CCEs. Larger amounts of precipitation were observed over WCEs, as compared to CCEs. The amount of precipitation associated with a WCE seemed to depend on the area and intensity of the eddy; larger, more intense eddies were associated with larger amounts of precipitation. Also, higher latent and sensible heat fluxes were observed over WCEs, as compared to CCEs, which could be responsible for the sudden increases in cyclone intensity. Interestingly, only one persistent WCE was found in the winter; whereas no persistent CCEs were found in the summer, calling for further case‐by‐case detailed investigation.