The regional climate model version 4.5 (RegCM4.5) is used to investigate thermal and dynamical processes associated with the Indian summer monsoon rainfall. The RegCM4.5 is run over the South Asia COordinated Regional Climate Downscaling Experiment (CORDEX) domain during 1990 to 2014 (25 years). The model realistically simulates the Indian summer monsoon rainfall (ISMR), tropospheric temperature and its gradient, and circulation patterns over the Indian region. The effect of Arabian Sea moisture transport on the ISMR is studied. It is argued that the weaker inward zonal transport and stronger outward meridional moisture transport from the Arabian Sea to the Indian subcontinent lead to reduced precipitation (dry bias) over India. The soil moisture over the Indian land points is significantly positively correlated to the precipitation over the region. The water budget analysis reveals that the moisture flux convergence values are slightly underestimated as compared to the precipitation minus evapotranspiration values over India. It is shown that the RegCM captures the eddy heat flux (EHF) and eddy momentum flux (EMF) variability over the Indian monsoon region. The model exhibits a distinct EHF dipole pattern between central India (20° N–30°N) and northern India (> 35° N) during the JJAS in the lower atmosphere. The monthly variability of the EMF over the Indian region suggests that EMF propagates northwards and upwards and becomes weaker from March onwards up to May. The EMF remains lowest during the monsoon season. The EMF again becomes stronger from Oct onwards with propagation of eddies in the opposite direction.

区域气候模型版本4.5（RegCM4.5）用于调查与印度夏季风降雨相关的热过程和动力过程。RegCM4.5在1990年至2014年（25年）内运行在南亚协调区域气候降尺度实验（CORDEX）领域。该模型真实地模拟了印度夏季季风降雨（ISMR），对流层温度及其梯度以及印度整个地区的环流模式。研究了阿拉伯海水分输送对ISMR的影响。据认为，从阿拉伯海到印度次大陆的较弱的向内地带传输和较强的向外的子午湿气传输导致印度降水减少（干偏）。印度陆地上的土壤湿度与该地区的降水量呈显着的正相关。水预算分析表明，与印度的降水量减去蒸散量相比，水汽通量收敛值被低估了。结果表明，RegCM捕获了印度季风区的涡热通量（EHF）和涡动量通量（EMF）的变异性。在低气压下的JJAS期间，该模型在印度中部（20°N–30°N）和印度北部（> 35°N）之间表现出独特的EHF偶极子模式。印度地区EMF的月度变化表明，EMF向北和向上传播，并且从3月开始到5月变弱。在季风季节，EMF保持最低。