Assessment of Lead-Lag and Spatial Changes in simulating different epochs of the Indian summer monsoon using RegCM4

The present study examines the efficacy of regional climate model RegCM4 in depicting onset, active, and break phases Indian summer monsoon (ISM). is driven by National Centers for Environmental Prediction (NCEP)/NCAR Reanalysis 1 project (NNRP1) data 28 years (1981–2008) each separately. High-resolution gridded rainfall analysis dataset India Meteorological Department (IMD) epochal report from Climate Center (NCC) are used verification. Besides assessment performance using qualitative methods, several standard statistical techniques to understand capability representing monsoonal epochs. A relationship between SST changes over Niño-3.4 region ISM all core (MCR) established where a strong dependency variation MCR with found than rainfall. satisfactory portraying spatial temporal intraseasonal variability (ISV) regions. It that higher simulating onset (dry days) active phases. limited skill phase due simulated low temperature weak pressure gradient which prevents convection given rise small region. mechanism pre-onset monsoon, advance ISV also well captured RegCM4. Weak tropospheric subcontinent during period causes delay subsequent high mid June faster progression active/break monsoon. At same time, simulation heavily regulated signal ENSO variability, forces through ICBC, modulates identifying interannual