The Lagged Impact of Autumn Surface Temperature Conditions on the Wintertime Beaufort High.

The Arctic has recently been undergoing a period of rapid warming, resulting in important changes to the sea ice cover as well as to the patterns of atmospheric circulation. During the winter of 2017, the Beaufort High collapsed as a result of the anomalous propagation of cyclones westward from the eastern Arctic. It has been suggested that warm conditions during the autumn of 2016 contributed to the winter collapse by limiting ice growth that provided an additional energy source for cyclones allowing them to propagate farther into the Arctic. We explore this hypothesis through the application of seasonally multivariate empirical orthogonal functions (MEOFs). The MEOFs were calculated for the autumn surface air temperature (SAT) field and the winter sea level pressure (SLP) anomaly field for the Arctic region from the ERA5 reanalysis for the period from 1979-2020. The leading seasonally lagged MEOF suggests that a positive relationship exists between autumn SATs and the Arctic Oscillation (AO) during the following winter. A complementary relationship is found for autumn sea ice concentration anomalies and the winter AO. These results suggest that a seasonally lagged link exists between surface conditions in the autumn and Arctic cyclone activity in the following winter that can modulate the intensity of the Beaufort High. The implications of this kink on the Arctic climate will be discussed.