Modeling analysis of storm surge states at Nome, Alaska

Storms that move into the western Bering Sea region have the potential to generate large storm surge responses along the eastern and northeastern Bering Sea coastal margins. Previous authors have discussed physical indications of surges approaching 4m. Surges of this magnitude are made possible by several factors, including the limited depth of the northern Bering Sea, which a continental shelf, and the fact that the storms often loiter, allowing maximum adverse sea states to be attained and maintained. This is coupled with a coastal region that is susceptible to surge, caused either by shallow relief or ice-rich coastal bluffs, which respond with severe erosion when they are undercut by elevated water levels. In a previous AGU presentation, occurrences of storm surge, observed at the water level recording station at Nome (up to 2006), were analysed in terms of their synoptic drivers. It was found that in some cases the marine state and locally-observed winds did not appear to match: in some instances a surge did not have locally-observed favorable winds, and in other instances strong, onshore flow was not accompanied by a surge. Using the surge modeling system ADCIRC a model grid was set up for the region off of Nome and operated with trial and observed winds to determine how extensive and how far offshore a wind field needs to be before a coastal surge response is observed. This presentation overviews these results.