Modeling the Present Three-Dimensional Ocean Circulation in the Nordic Seas

Robert William Helber, U.S. Naval Research Laboratory, Ocean Dynamics and Prediction, Stennis Space Center, MS, United States, Travis Smith, Naval Research Laboratory, Ocean Sciences, Stennis Space Center, MS, United States, Gleb Panteleev, Naval Research Laboratory, Stennis Space center, MS, United States, Jay F Shriver, Naval Research Laboratory, Stennis Space Center, Stennis Space Center, MS, United States and David A Hebert, US Naval Research Laboratory, Ocean Sciences Division, Stennis Space Center, MS, United States
Arctic and High latitude North Atlantic Ocean circulation forecasting at the Naval Research Laboratory (NRL) has traditionally focused on sea-ice prediction because the surface wind driven circulation tends to dominate the Arctic Ocean flow. Recent research, however, has suggested that the subsurface ocean structure has changed substantially, such that the role of ocean circulation is having a greater impact on sea-ice dynamics and kinematics. For these reasons, NRL is now investigating the ocean subsurface thermohaline structure and its influence on the circulation from the Arctic Ocean to the North Atlantic. This presentation highlights the challenges of forecasting present ocean conditions that have changed relative to the Navy’s operational ocean climatology. We utilize four different numerical ocean models, each with their own advantages. Presently, our most complete modeling results, showing large tidal flows through the Denmark Strait, are from the Navy’s Couple Ocean and Atmosphere Prediction System (COAMPS) that includes an atmospheric model and the Navy Coastal Ocean Model (NCOM) with barotropic tides. Since NCOM is a Boussinesq, sigma-z level model, we also investigate water mass evolution using Arbitrary-Lagrangain Eulerian (ALE) modeling capabilities. Results include, the Hybrid Coordinate Ocean Model (HYCOM), which is non-Boussinesq with ALE capabilities, demonstrated adherence to climatological ocean structure. The Modular Ocean Model, version 6 (MOM6), which is also ALE but new to regional modeling, produces the major current structures in the Nordic Seas. MIT general circulation model (MITgcm), idealize experiments demonstrate the non-hydrostatic evolution of thermobaricity in high-latitude ocean flows. By comparing volume, heat, and freshwater transport through straits and other regions with these contrasting model formulations, we investigate variability sensitive to changing subsurface ocean structure, freshwater input, and heat exchanges.