Based on aerological observations over the Arabian Sea and adjoining north Indian Ocean, taken on board USSR research vessels during MONEX-1973, patterns of vergence of air and water vapour fluxes are studied. The influence of the Arabian Sea on the fluctuations in intensity of the summer monsoon over the west coast of India is shown. It is inferred that evaporation exceeds precipitation over the east Arabian Sea near the west coast of India even during active monsoon.A zonal cell with the ascending limb over the east Arabian Sea and the descending branch over the west Arabian Sea is proposed.

The present study has been undertaken to examine the oceanic heat budget components and their variability over the Indian seas in relation to the extreme monsoon activity (flood/drought) over the Indian subcontinent. For this purpose, various components of oceanic heat budget have been analysed for pre-monsoon (March-May), monsoon (June-September), post-monsoon (October-December) and winter (January-February) seasons over India. The data base used in this study consists of mean monthly marine meteorological fields for 30 years (1950-1979), which is a part of the Comprehensive Ocean Atmosphere Data Set (COADS) analysed at I" latitude by 1" longitude resolution.The mean fields of incoming shortwave radiation flux over the Indian seas in different seasons vary in accordance to the sun's position and cloud cover variations. The latent heat flux undergoes considerable seasonal variations, particularly over the Arabian Sea. There is a dominance of latent heat flux (representing the oceanic heat loss) over shortwave solar flux (representing the oceanic heat gain) during the monsoon season, which results in a zone of net oceanic heat loss over the central Arabian Sea. This feature produces a positive feedback for the maintenance of deep cumulus convection over the Arabian Sea in this season.It is also found that oceanic heat budget components over the Indian seas exhibit significant variability in relation to the extreme monsoon activity leading to flooddrought over India. Based on the above analysis, mean monthly variations of the oceanic heat budget components over three smaller sectors of the Indian seas, namely west equatorial Indian Ocean, Arabian Sea and Bay of Bengal, are also examined. The variations are found to be considerably different between the two extreme categories of the monsoon. It becomes evident fiom this study that the oceanic sectors of west equatorial Indian Ocean and Bay of Bengal experience a large reduction of net heat flux from April to May prior to a flood monsoon season over India. This suggests that a spectacular increase of latent heat flux and decrease of shortwave flux occurs over these oceanic sectors, leading to a sharp reduction of net heat flux.

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In this study, a dynamically downscaled regional climate model (RegCM4.3) is used to study the Indian summer monsoon (ISM) surface air temperature over the South‐Asia CORDEX domain using six convection schemes during 1986–2010. The spatial and temporal variability of mean surface air temperature has been analysed with reference to the India Meteorological Department (IMD) analysis data using various statistical scores. The sensitivity experiments in selecting the best convective parameterized schemes have been performed in simulating the surface air temperature during the summer monsoon season (June–September) over India and its five sub‐regions such as Northwest India, Northcentral India, West Peninsular India, Eastern Peninsular India, and Southern Peninsular India. The model results show the tendency of overestimation of surface air temperature mainly in four cumulus parameterization schemes (CPSs) that is, Tiedtke, Emanuel, Mix98, and Mix99 of RegCM4.3 during the JJAS, where Grell and Kuo CPSs show better agreement with the IMD data. Overall, Grell CPS has a close resemblance to the observation data with a minimum root mean square error, mean absolute error, lowest mean absolute percentage error (MAPE), and higher correlation coefficient. The model simulated results have also been investigated further using modified Nash Sutcliffe efficiency and modified Willmott's degree of index. These analyses confirm the potentiality of the Grell CPS followed by the Kuo CPS in simulating interannual variability of the surface air temperature over Indian and its five sub‐regions. The MAPE in Grell and Kuo CPSs are 0.004 and 0.013°C during monsoon season over India, respectively. The inter‐scheme difference in simulating surface air temperature is linked with the generation of low cloud convection and warming‐induced atmospheric moisture advection in the schemes. Therefore, Emanuel, Tiedtke, and Mix98 CPSs have shown a persistent nature of overestimation in surface air temperature variability during JJAS. It is also inferred that after removing the systematic mean bias from the RegCM4.3 model simulated outputs; the skill of Emanuel, Mix98, and Mix99 could be useful over the Indian subcontinent except for the southern peninsular region.