1.4      Using the Coupled-Ocean-Atmosphere-Waves-Sediment-Transport (COAWST) Modeling System to Investigate Storm Dynamics.

Warner, John C., U.S. Geological Survey, Coastal/Marine Hazards and Resources Program, Woods Hole, MA, Joseph B. Zambon, Ruoying He, North Carolina State University, Department of Marine, Earth, and Atmospheric Sciences, Raleigh, NC, Maitane Olabarrieta, Department of Civil and Coastal Engineering, University of Florida, Gainesville, FL, and Christie Hegermiller, Woods Hole Oceanographic Institution, Woods Hole, MA

In order to improve simulations of coastal storms and impacts, we have developed the Coupled-Ocean Atmosphere-Waves-SedimentTransport (COAWST) Modeling System that couples the ocean model ROMS, atmosphere model WRF, wave models of SWAN, WaveWatch III, or InWave, and the Community Sediment Transport Modeling System. COAWST is an open-source community developed system with an active user base, biennial trainings, and code distributed on github. We will describe the coupling mechanisms that use the Model Coupling Toolkit, exchange of data fields between model components, and new physics implemented into each component to utilize transferred data fields. Comparisons between several hurricane scenarios with increasing levels of complexity demonstrate how additional physical interactions modify the simulations and identify significance of processes for storm intensity, strength, waves, and ocean mixing. For example, simulations of Hurricane Ivan (2004) in the Gulf of Mexico showed stronger dependence on ocean SST coupling, whereas Hurricane Ida (2009) has a stronger effect from surface waves modifying the hurricane intensity.