High-Resolution Simulation of West coast Convective Extremes Driven by Arabian Sea Warming: The IOLA Coupled Framework

Abstract

Recent climate-driven changes across the Indian Ocean, most notably the rapid and persistent warming of the Arabian Sea relative to the Bay of Bengal have intensified the demand for modeling systems that can capture evolving air–sea interactions with far greater precision. This anomalous Arabian Sea warming has boosted ocean heat content and near-surface moisture, supporting not only more frequent and rapidly intensifying cyclones but also an increase in convective activity along the west coast of India. The west-coastal belt, particularly during the pre-monsoon and monsoon transition periods, has experienced more vigorous and localized thunderstorms, heavy rainfall episodes, and offshore trough enhancements, all of which are strongly modulated by fine-scale thermodynamic and dynamical features often missed by coarseresolution models. Given these emerging complexities, high-resolution (1–2 km) modeling has become essential for resolving the structure of deep convection, mesoscale vortices, and moisture convergence zones that govern extreme precipitation along the western coastline and the adjoining oceanic region. Such resolutions allow for more accurate depiction of storm-scale processes, boundary-layer evolution, and surface flux feedbacks as critical ingredients for predicting high-impact events influenced by Arabian Sea warming. To meet these challenges, the Indian Ocean–Land–Atmosphere (IOLA) Coupled Mesoscale Prediction System has been developed as a unified, seamless framework capable of tracking severe weather across both oceanic and continental domains. By integrating a nonhydrostatic dynamical core, storm-following high-resolution nests, ocean coupling, and flexible physics configurations, IOLA provides a consistent platform to simulate the full spectrum of extreme weather from rapidly intensifying cyclones over the Arabian Sea to convective outbursts along the west coast and inland. This unified approach positions IOLA as a next-generation system for improving early warnings and enhancing resilience to India’s evolving spectrum of severe weather.