AbstractsGeography &GIS

The Arctic climate has rapidly changed over the last several decades, especially across the western Arctic Ocean where dramatic alterations to the end-of-summer sea ice extent and autumn freeze-up have been observed. While the spatiotemporal patterns of sea ice variability are well-documented by modern satellite instrumentation, the regional atmospheric causes and subsequent consequences of sea ice changes over this portion of the Arctic remain unclear. This dissertation research utilizes synoptic climatological techniques to evaluate the aforementioned sea ice-climate interactions in the western Arctic and high latitude North America since 1979. Separate atmospheric pattern classifications comprised of daily mean, gridded, sea level pressure and 1000-500 hPa thickness data are developed and associated with the western Arctic September sea ice minima and the timing of continuous autumn freeze-up. Data from a weather typing scheme known as the Spatial Synoptic Classification (SSC) is also employed to holistically evaluate near-surface temperature and moisture changes during the autumn and winter months, as indicated by the anomalous occurrences of the dominant SSC weather types (Dry Polar (DP) and Moist Polar (MP)) within those months, throughout the terrestrial North American Arctic that coincide with western Arctic sea ice freeze-up variability. Results suggest that recent summer increases in Beaufort Sea High pressure patterns, especially during June, play a significant, dynamic role in both the multidecadal and interannual end-of-summer ice extent losses and freeze-up delays witnessed in the region. The general persistence of ice cover formation later into autumn also parallels a transition of DP to MP weather types across much of Alaska and Yukon Territory during autumn and winter months over time. Future work will explore connections between sea ice cover variability, large-scale atmospheric circulation, and surface weather conditions across the Northern Hemisphere high and middle latitudes.