Modeling effects of tidal and wave mixing on circulation and thermohaline structures in the Bering Sea: Process studies

Ocean circulation and the tidal current in the Bering Sea are simulated simultaneously using a coupled ice-ocean model (CIOM) with tidal and parameterized wave mixing to investigate several important physical processes. The simulated circulation pattern in the deep basin is relatively stable, cyclonic, and has little seasonal change. The Bering Slope Current is estimated at 5 Sv and the Kamchatka Current at 20 Sv. The modeled volume transports through the Aleutian passes compared reasonably well with observations. It is confirmed that subtidal clockwise circulation around St. George and St. Paul islands are driven by tidal rectification. The simulation results show that wind-wave mixing and tidal stirring are the main factors controlling the formation of the upper and the bottom mixed layers, respectively. The mechanism of thermocline and the cold pool (summer minimum-temperature water) formation in the middle shelf are investigated in depth. The CIOM reproduces the cold winter-convective water in the middle shelf that forms the bottom cold pool, which persists throughout the summer until sea surface cooling and strong wind mixing in fall, leading to an unstable vertical water column and eventually to vertically well-mixed water in the winter. Sensitivity experiments show that tidal and wind-wave mixing are two important factors in accurately estimating the volume of the cold pool, which is the ideal marine habitat for cold water species.