Explaining the Seasonal Cycle of Summer Monsoon Rainfall Over the Arabian Sea and Western India

The intensity and spatial distribution of rainfall over the Arabian Sea and western India undergo distinct changes throughout the summer monsoon season. Accurately reproducing the observed seasonal cycle of rainfall has proven challenging for climate models, primarily due to their varying representations of convection. By employing a process-oriented diagnostic (POD) based on the empirical relationship between tropical precipitation and the buoyancy of near-surface air parcels, we aim to understand and identify process-level sources of intermodel spread in the seasonal cycle of rainfall. We apply the POD to observational data to characterize the physical processes that drive rainfall in this region. We then compare these findings with climate model output to determine how well each model represents these processes, and explore implications for predicted sensitivities of rainfall in this region to future warming. By enhancing process-based understanding of monsoon rainfall seasonality, this work provides insights that are crucial for guiding model improvements and developing expectations for how rainfall will change under a future warmer climate.