Development of a Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) Modeling System

Abstract

a b s t r a c tUnderstanding the processes responsible for coastal change is important for managing our coastal resources, both natural and economic. The current scientific understanding of coastal sediment transport and geology suggests that examining coastal processes at regional scales can lead to significant insight into how the coastal zone evolves. To better identify the significant processes affecting our coastlines and how those processes create coastal change we developed a Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System, which is comprised of the Model Coupling Toolkit to exchange data fields between the ocean model ROMS, the atmosphere model WRF, the wave model SWAN, and the sediment capabilities of the Community Sediment Transport Model. This formulation builds upon previous developments by coupling the atmospheric model to the ocean and wave models, providing one-way grid refinement in the ocean model, one-way grid refinement in the wave model, and coupling on refined levels. Herein we describe the modeling components and the data fields exchanged. The modeling system is used to identify model sensitivity by exchanging prognostic variable fields between different model components during an application to simulate Hurricane Isabel during September 2003. Results identify that hurricane intensity is extremely sensitive to sea surface temperature. Intensity is reduced when coupled to the ocean model although the coupling provides a more realistic simulation of the sea surface temperature. Coupling of the ocean to the atmosphere also results in decreased boundary layer stress and coupling of the waves to the atmosphere results in increased bottom stress. Wave results are sensitive to both ocean and atmospheric coupling due to wave-current interactions with the ocean and wave growth from the atmosphere wind stress. Sediment resuspension at regional scale during the hurricane is controlled by shelf width and wave propagation during hurricane approach.Published by Elsevier Ltd.

A fully coupled atmosphere–ocean wave modeling system for the Mediterranean Sea: interactions and sensitivity to the resolved scales and mechanisms

“…During the last several years, the importance of coupling at regional scales has challenged the research community (Hodur et al, 2002;Lionello et al, 2003). Due to the limited spatial and temporal interaction scales between atmosphere and ocean, the direct and sufficient response between the coupled models is a substantial factor (Warner et al, 2010).…”

“…More specifically, the hurricane force winds increase the drag coefficient magnitude of the sea surface that leads to a decrease of the wind speed and a change in the wind direction. Generally, the feedbacks ultimately create non-linear interactions between different components and make it difficult to assess the full impact on each specific model (Warner et al, 2010).…”

“…The United States Geological Survey (USGS) operates the coupled ocean-atmosphere-wave-sediment transport (COAWST) modeling system, which is integrated by the model coupling toolkit to exchange data fields between the ocean model ROMS (regional ocean modeling system), the atmosphere model WRF (weather research and forecasting model), the wave model SWAN (simulating waves nearshore), and the sediment capabilities developed as part of the Community Sediment Transport Modeling Project (Warner et al, 2010). The Earth system model (CNRM-CM5, Centre National de Recherches M'etéorologiques Coupled Global Climate Model version 5) running operationally at Meteo-France consists of several existing models designed independently and coupled through the OASIS software (Redler et al, 2010).…”

Impact of operational model nesting approaches and inherent errors for coastal simulations

“…Typically operational systems consider 2 model grids (e.g. Warner et al, 2010;Sánchez-Arcilla, et al, 2014) with the highest resolution in the order of 1 -2km. The preoperational POLCOMS system for the Irish Sea similarly applies a 2 nest system, with a 12 km Atlantic Margin model (AMM), extending from 11.92 °W to 12.92 °E and 48.06 °N to 62.95 °N, and a one-way nested 1.8 km Irish Sea model (O'Neill et al, 2012).…”

An integrated ocean circulation, wave, atmosphere, and marine ecosystem prediction system for the South Atlantic Bight and Gulf of Mexico

“…Compared with global models, SABGOM has several advantages, including (1) a relatively high horizontal resolution, which enables a better representation of coastal geometry and ocean bathymetry; (2) incorporation of tides and riverine inputs as boundary conditions, which can improve forecast accuracy of sea-level variations, vertical mixing, and river plume dynamics; (3) built-in ecosystem and sediment modelling components (Warner et al 2008;Fennel et al 2006Fennel et al , 2011, which are crucial for addressing marine environmental issues; and (4) support of model nesting and coupling with other physical models [e.g. WRF and SWAN (Warner et al 2010)]. Figure 10 shows the surface currents in the northern Gulf of Mexico forecasted by SABGOM, HYCOM/NCODA, RTOFS, and the ensemble mean of the three solutions on 00Z 7 June 2013.…”