Autumn and Winter Atmospheric Response to Western Arctic Autumn Anomalous Surface Heat

Abstract:

One of the most dramatic recent changes in Arctic climate is the reduction in sea ice, particularly in the autumn in the western Arctic. This work considers the anomalous sensible heat to the atmosphere from this additional open water. Initial results analyze this additional heat and resulting changes in temperature and circulation both locally, within the Arctic, and at lower latitudes in autumn throughout the winter. Results show the anomalous additional heat in the western Arctic persists in the area for 2 months. Comparisons of northern hemisphere surface circulation between positive and negative anomalies of sensible heat show stronger low pressure centered near the Gulf of Alaska with high pressure centered in the Laptev Sea for positive heating (from the surface to the atmosphere) and a largely opposite signal occurs for negative heating. Elevated near surface temperatures for anomalously large heating to the atmosphere occur in the western Arctic around the ocean periphery to the GIN Seas which persist, particularly in the GIN Seas area, through late winter. The initial mid-level circulation signal (500mb heights) to anomalous heating is lower heights over the western Arctic into Alaska and northwestern Canada, ridging in the southwest US, and high pressure over the Laptev/Kara/Barents Seas. A persistent Rossby wave signal then persists into winter with lower heights over the western Arctic into Alaska and down the western North American coast as well as over Europe with higher heights over the Aleutian Islands, northeastern Canada, and northeastern Russia centered near the Barents Sea.