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

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), a region characterised by complex coastlines, shallow seas, and strong air–sea interactions. 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. Its primary contribution is the development of a fully coupled system that enables two-way interactions between atmosphere, ocean, and waves at kilometre scale. Before coupling, the ocean and wave components are configured in standalone mode for the WMC. 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. This agreement is maintained in the fully coupled configuration. 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 individual Sumatra squall events further suggest that coupling may influence the organisation and persistence of eastward-propagating convection. The magnitude of this influence appears to depend on the dominant convective regime, although a larger sample of events is needed to confirm this dependence. Overall, cSINGV provides a physically consistent framework for representing coupled processes in the WMC and a useful platform for investigating air–sea–wave interactions at convection-permitting scales.