cSINGV v1.0: Development and evaluation of a 1.5 km coupled atmosphere-ocean-wave modelling system for the Western Maritime Continent

Abstract. This study presents cSINGV v1.0, a high-resolution (1.5 km) regional coupled atmosphere–ocean–wave modelling system developed for the Western Maritime Continent (WMC). The system integrates a convection-permitting atmospheric model (SINGV) with newly configured ocean (NEMO) and wave (WAVEWATCH III) components within a unified coupling framework based on the Regional Coupled Suite and OASIS3-MCT coupler. The primary contribution of this work lies in the development of a fully coupled system enabling two-way interactions between atmosphere, ocean, and waves at kilometre scale. The ocean and wave components are specifically configured and optimised for the WMC, a region characterised by complex coastlines, shallow seas, and strong air–sea interactions.

The model is evaluated using a six-month simulation (January–June 2019) against multiple observational and reanalysis datasets. The ocean and wave components show good agreement with reference datasets, with sea surface temperature errors generally below 0.5 °C and significant wave height errors around 0.2 m. The influence of coupling is assessed by comparing the coupled and uncoupled atmospheric configurations. Results show that coupling improves the spatial organisation of precipitation, the diurnal cycle over the ocean, and the offshore propagation of convection, while differences in near-surface atmospheric variables remain modest. Process-based analysis indicates that these improvements are primarily linked to enhanced latent heat flux driven by thermodynamic air–sea feedbacks associated with sea surface temperature variability. Case studies of Sumatra squall events further indicate that coupling can influence the organisation and persistence of eastward-propagating convection, with the magnitude of this impact depending on the dominant convective regime. Overall, cSINGV provides a physically consistent framework for representing coupled processes in the WMC and offers a useful platform for investigating air–sea–wave interactions at convection-permitting scales.