Pacific Inflow and Mesoscale Eddy in the Western Arctic: Based on FESOM with Regional Focus

A global finite element sea ice-ocean coupled system (FESOM) with regional focus on the Chukchi-Beaufort shelf region is configured to investigate the northward transport of the summer Pacific water, especially on the role of mesoscale process. Because of its ability to locally adjust resolution, FESOM offers a convenient global modeling framework thus avoiding open boundaries and nesting. The finest resolution in the focus region is about 3km, which is sufficient to resolve the mesoscale eddy nearby. Circulation pattern and sea ice variation around the Chukchi Sea and Alaskan coast (Beaufort Sea side) are well reproduced compared with previous numerical and available observational data. Special attention is paid to the summer Alaskan Coastal Current (ACC), mostly running eastward along the Alaskan coast. Due to the solar radiation over the open water in the lower latitude, the ACC upper layer water has a high temperature (even reached to 5oC or more in the summer). Eddy generation process is captured during the summer when sea ice has retreated away from the coast. Downstream of the ACC after the Barrow Point, surface-intensified anticyclonic eddy is frequently generated and propagate towards the Canada basin. Such surface-intensified anticyclonic eddy has a warm core, with its source from the high-temperature ACC water. A typical warm core eddy is traced; it is trapped just below the summer sea ice melt water and has a thickness of about 60m. Temperature in the core of the eddy reaches to 2-3oC and most part of the water inside of the eddy with a temperature over 1oC. With a definition of the eddy boundary, we calculated the heat content of the eddy, which can induced 1m melt of sea ice with an area of 1600km2 under extreme conditions.