Comparison of High-Resolution Model Output in the Beaufort Gyre

Elizabeth Douglass, Naval Research Lab, Stennis Space Center, United States, Patrick J Hogan, Stennis Space Ctr, Stennis Space Center, MS, United States and Alan J Wallcraft, Florida State University, Center for Ocean-Atmospheric Prediction Studies, Tallahassee, FL, United States
We compare ice and circulation patterns in the Beaufort Gyre from several products of the HYbrid Coordinate Ocean Model (HYCOM). The first two are from the Naval Research Laboratory’s Global Ocean Forecast System (GOFS), an assimilative, coupled ocean-ice model that produces global operational model forecasts. GOFS 3.1 has a nominal resolution of 1/12.5°, or roughly 3.5 km in the Beaufort Gyre region, while GOFS 3.5 has a nominal resolution of 1/25°, or roughly 1.8 km in that same region. These will be compared with a non-assimilative, regional version of HYCOM coupled with the ice model CICE, referred to as BFG (Beaufort Gyre). This regional version also has a resolution of 1/25°, and is the first attempt at a coupled HYCOM+CICE at high latitudes such that ice is transported through the boundaries. The two GOFS products agree closely on assimilated quantities such as ice edge, while differences with BFG in ice concentration and surface temperature are evident during the melting season. However, at depths below approximately 200 m, GOFS 3.5 and BFG agree closely, demonstrating a subsurface layer of warm, Atlantic water that matches observations, while the Atlantic water in the lower resolution GOFS 3.1 model is thinner and cooler. All differences in melting, refreezing, and subsurface circulation between these three depictions of the Arctic region from May 2017 through April 2018 will be examined.