A Regional Earth System Modeling Platform for the Gulf of Mexico

The Gulf of Mexico is a marginal sea that is under the impact of both large-scale atmospheric and oceanic circulation (e.g., tropical cyclones Loop Currents) as well as enormous water, sediment, and nutrient inputs from the Mississippi-Atchafalaya River System. With a changing climate, the northern Gulf of Mexico is suffering from various coastal hazards including sea-level rise and land loss, eutrophication and hypoxia, ocean acidification, hurricanes, and compound flooding. A key toolset to untangle the various processes involved in these coastal disasters is a Regional Earth System Model that incorporates atmospheric, oceanic, and river processes as well as, most importantly, the interaction among them. Such a toolset is also expected to inform stakeholders and policy makers in planning and decision-making regarding various coastal hazards. The open-source, community-developed Coupled Ocean Atmosphere Waves Sediment Transport (COAWST) modeling dynamically couples multiple models, including the Regional Ocean Modeling System (ROMS), Simulating WAves Nearshore (SWAN), WAVEWATCH III, the Weather Research and Forecasting (WRF) model, the INfragravity WAVE model (INWAVE), and the Community Sediment Transport Modeling System (CSTMS). Recently a process-based land surface/hydrological model (WRF-Hydro) is incorporated into the COAWST platform and enables the dynamical coupling between ocean and land processes. Here we demonstrate several recent developments and applications of COAWST in the Gulf of Mexico, which includes hydrodynamics, sedimentation, nutrient cycling, compound flooding during hurricane events, land loss-associated carbon export from the estuary to the coastal ocean, multi-decadal assessment of the carbon cycling, climate change's impact on coastal watershed sediment yields, as well as the development of hypoxic water on the Louisiana-Texas Shelf. These studies feature the coupling among air-sea, physical-biogeochemical, atmosphere-ocean-wave-sediment-nutrient, hydrological-oceanic processes and demonstrate the feasibility of regional earth system model development and its potential for coastal hazards management.