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Abstract
Wind-generated waves play an important role in the coupled climate system near the atmosphere/ocean/sea ice interfaces. These waves occur on scales smaller than 1 km and 1 min and arise primarily from wind forcing that is mediated by ocean currents and sea ice. Since these processes are currently unaccounted for in E3SM, our goal is to provide the capability to include feedbacks between wind-waves with the atmosphere, ocean, and sea-ice components by introducing coupled wind-wave physics into the modeling system. To do this, we are implementing a global, multi-resolution, third-generation phase-average wave model called WaveWatch III into the E3SM’s CIME/MCT coupling framework. Since resolving the small scales of individual waves globally would be computationally intractable, phase-average wave models, such as WaveWatch III, parameterize the sea state at climate modeling scales by solving the wave action density equation. This equation governs the propagation of the wave spectrum through the ocean and contains source and sink parameterizations that represent the generation of waves by wind, wave-wave interactions, sea ice-wave interactions, wave breaking, etc. Incorporation of WaveWatch III into E3SM will allow for investigation of several coupled processes that may play a role in bias reduction in climate simulations. An emphasis of this work will be sea ice interactions, e.g., ice shields the ocean from local wave generation, waves impact the floe size distribution via ice breakage, and ice dissipates wave energy by attenuating wave heights. Other bias reduction capabilities to consider for future incorporation into E3SM using WaveWatchIII include enhanced ocean surface albedo due to white-capping of waves, improved momentum transfer between the atmosphere to the ocean due to increased form drag / sea surface roughness, and incorporation of Langmuir turbulent mixing caused by the alignment of wave-generated Stokes drift and atmospheric winds. The inclusion of waves, along with regional refinement, also provides the opportunity to accurately predict wave-driven coastal processes such as storm surge and coastal erosion. Therefore, the addition of wind-wave physics into E3SM will not only account for critical global climate processes related to ocean-wave-sea ice dynamics, but will also create a path to assess how long-term climate trends, such as regional sea-level rise, affect coastal communities and infrastructure.
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