Atmospheric forcing of the Beaufort Sea ice gyre:Surface pressure climatology and sea ice motion

摘要

The Beaufort Gyre (BG) typically rotates anticyclonically and exerts an importantcontrol on Arctic Sea ice dynamics. Previous studies have shown reversals in the BG torotate cyclonically during summer months and, in recent decades, throughout the annualcycle. In this investigation, we explore the synoptic climatology of atmospheric forcingand its relationship to sea ice motion and BG reversals. A catalog of daily synopticweather types is generated for the Beaufort Sea Region covering the period 1979 to 2006using NCEP/NCAR reanalysis mean sea level pressure data, principle components, andk-means cluster analyses. Mean synoptic type frequency, persistence, and durationvalues are calculated for each synoptic type and contrasted between the summer andwinter seasons. Daily synoptic types are linked to changes in sea ice vorticity by usingcorrelation analysis on lagged sea ice vorticity data. Lag correlations are found betweensynoptic types and sea ice vorticity smoothed over a 12-week running mean andshow that cyclonic types, which promote southerly or easterly atmospheric circulationover the southern Beaufort Sea, commonly precede summer reversals. Furthermore,significant seasonal within-type variability in sea ice vorticity is detected within thesynoptic types illustrating the importance of seasonal variability on these processes.