5.2 An Integrated Tide and Storm Surge Model for the Gulf of Alaska and Bering, Chukchi, and Beaufort Seas Incorporating Ice Coverage

Wednesday, 25 January 2017: 1:45 PM
Conference Center: Chelan 4 (Washington State Convention Center )
Brian Joyce, Notre Dame, South Bend, IN; and J. Westerink and R. Grumbine

An integrated tide and storm surge model has been built for the Gulf of Alaska and Bering, Chukchi, and Beaufort Seas with a focus on coastal western Alaska. The model uses the Advanced Circulation (ADCIRC) basin to channel scale unstructured grid circulation code. The grid is an accurate representation of the coastal environment in the region, with grid resolution ranging from 3000 m in the deep ocean to 25 m in nearshore areas of interest on the Alaskan coastline. ADCIRC is used in conjunction with tidal forcing from various global tidal models and atmospheric forcing and ice coverage extracted from the National Centers for Environmental Prediction’s Climate Reanalysis. The model's tidal solution has been validated at 115 stations along the Alaskan coastline. In addition, the model has been validated for summer storms where ice coverage is not present in the model domain. Sea ice is incorporated into the model through a parameterization of the wind drag coefficient which modifies the transfer of momentum from the wind to the water in the presence of ice coverage. For winter storms, two large storms with distinctly different ice coverage scenarios were chosen to exhibit the effect changing sea ice extents and concentrations could have on the resulting storm surge. When ice is not completely formed, and found in concentrations around 50% along the coast, there is the potential for an increase in surge. However, fully formed ice at concentrations greater than 90% has the capability to slightly decrease water levels in a relatively small, large scale protective effect. As sea ice coverages and extents are affected by climate change, it will be important to quantify the effect this change will have on storm surge.

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