The influence of the Alaskan Gyre on the coastal circulation in the Gulf of Alaska

A wind-driven, nonlinear, reduced gravity, primitive equation model is used to simulate the circulation of the northeast Pacific Ocean including the northeast Gulf of Alaska. The model includes the affects of bottom topography. Model geometry encompasses the entire Gulf of Alaska region from Vancouver Island to west of Kodiak Island. This region is traditionally beyond the latitude limits of the reduced gravity model imposed by a weakening thermocline away from the equator. The model resolution, 0.025° in latitude and longitude, is very fine. This is the first time that a model of this type and resolution has been successfully run at these latitudes. Although we expected that such resolution would allow the mesoscale eddy field to develop, it did not. One reason may be the coarse spatial and temporal winds. Twenty year of Comprehensive Ocean-Atmosphere Data Set pseudo wind stress data used to drive the model are statistically analyzed to obtain a wind stress climatology. After model spin-up, the monthly stresses for 1986–1989 are used to drive the model. The model reproduces many of the regional oceanographic features such as the Alaskan Gyre, the Alaska Current, the Alaska Coastal Current, the Sitka eddy, and an intense, cyclonic eddy (that has not yet been reported in the literature) northwest of the Queen Charlotte Island in the spring. In addition, the model displays seasonal and interannual variability. Model results are validated through comparisons with National Ocean Service coastal sea level records and a multilayer, oceanic basin scale model being run at the Institute for Naval Oceanography.