Understanding Synoptic Influence on Clouds and Radiation at Summit Station Greenland Using Self-Organizing Maps

Investigating the relationship between synoptic scale atmospheric circulation and measurable surface processes is crucial to our understanding of Arctic climate. Self-organizing maps (SOMs) have proven to be a capable tool in objectively classifying and analyzing the influence of synoptic circulation on regional climate as well as in situ observations. Using sea level pressure (SLP) data from the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis project, this analysis constructs a SOM classification of the synoptic circulation over the Greenland Ice Sheet (GrIS) to demonstrate the connection between the regional atmospheric flow and in situ observations at Summit Station. Specifically, this analysis illustrates the relationship between clouds, radiative forcing, temperature, and synoptic state, as these variables are determinants of central ice sheet mass balance, regional climate, and other Arctic phenomena. The resulting classification shows that the strength and location of cyclonic features drive regional climate, with meridional advection patterns responsible for anomalous synoptic warming at Summit Station. However, only a portion of these warming patterns cause substantial positive net anomalous cloud radiative forcing at Summit, related to the advection of moisture. The primary synoptic feature causing an increase in net cloud radiative forcing (CRF) values is an anomalous low in Baffin Bay to the west of the ice sheet. Seasonal frequency variations of this pattern are linked to seasonal variability of CRF. Finally, regional circulation is statistically tied to daily index values of the polar Arctic Oscillation (AO), and daily variability on the ice sheet is connected to regional synoptic flow, as well as large-scale polar circulation.