A vorticity-based analysis of the spatial and temporal characteristics of the Beaufort Anticyclone

Abstract

The Beaufort Anticyclone is the dominant pressure feature over the Arctic Ocean in all seasons and has a large influence on the surface wind regime and sea ice motion. Sea level pressure (SLP) from the National Center for Atmospheric Research/National Centers for Environmental Prediction Reanalysis is used to create a vorticity metric to investigate the spatial and temporal characteristics of the Beaufort Anticyclone from 1948 to 2008. Correlations between vorticity averaged over the Beaufort Anticyclone region and Northern Hemisphere SLP are strongest south of Alaska and north of Siberia. These two areas are also present in SLP composite maps based on extremes of the vorticity metric. Temporal characteristics are investigated using running means and spectral analysis in which the only predominant peak is the annual cycle. If 30 year time periods are compared, little to no trend in the vorticity metric is found except in October-December, where the more recent time period has slightly larger vorticity magnitudes. The Beaufort Anticyclone vorticity metric is correlated with teleconnection index values; the Pacific Ocean patterns show a larger influence than the Atlantic patterns, including the Arctic Oscillation, which has been shown in recent studies to have little correspondence to changes in sea ice in the early 21st century. A significant correlation is found with the Pacific North American pattern in all seasons except summer. The El Nio-Southern Oscillation shows a significant correlation with the vorticity metric in winter, and the Pacific Decadal Oscillation shows a significant correlation in winter and spring. © 2011 by the American Geophysical Union.