Characteristics of the Beaufort Sea High

A prominent feature of the annual mean sea level pressure (SLP) field for the arctic region is an anticyclone centered north of Alaska, often referred to as the Beaufort Sea High (BSH). While variability in the BSH has strong impacts on sea ice conditions that complicate interpretation of the steep downward trend in summer sea ice extent, the drivers of BSH variability have received surprisingly little attention. Our study examines characteristics and variability of the BSH using reanalysis data for the period 1979–2009. The BSH appears as a closed anticyclone in climatological mean SLP fields for spring, summer and autumn. In winter, the Beaufort Sea is instead part of a pressure ridge extending from the Siberian High to the Yukon High over northwestern Canada. As assessed from 6-hourly surface winds, the mean frequency of anticyclonic flow over Beaufort Sea region is fairly constant through the year. For all seasons, a strong high at the surface is linked to regional split flow at 500 hPa, in which a ridge with fairly tight height gradients linked to the anomalously strong BSH is separated by a region of slack height gradients from the western North American ridge to the south. In all seasons but autumn, a strong BSH is associated with positive lower-tropospheric temperature anomalies covering much of the Arctic Ocean; positive anomalies are especially pronounced in spring. Seasons with a weak anticyclone show broadly opposing anomalies. A strong high is found to be a feature of the negative phase of the summer Northern Annular Mode, the positive phase of the Pacific North American (PNA) wavetrain and the positive phase of the Arctic Summer Dipole and Pacific Decadal Oscillation. The unifying theme is that to varying degrees, the high latitude 500 hPa ridge associated with the surface BSH represents a center of action in each teleconnection pattern.