Examining Atmospheric Drivers of Temperature, Clouds, and Radiation at Summit, Greenland, with Self-Organizing Maps

The relationship between regional atmospheric circulation and local surface processes is crucial to our understanding of Greenland and climate. 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 self-organizing map (SOM) classification of the synoptic circulation near the Greenland Ice Sheet (GrIS) to demonstrate the connection between regional atmospheric flow and in situ observations at Summit Station. The SOM objectively classifies SLP patterns from observations using an artificial neural network competitive learning, a comprehensive representation of atmospheric circulation is mapped. While prior research has investigated the long term trends between circulation and observations, this analysis uses SOMs to identify unique patterns and processes related to daily variability over the GrIS. Specifically, highlighting the relationship between moisture, cloud properties, 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 synoptic warming at Summit Station. A portion of these synoptic warming patterns are also associated with substantial positive net anomalous cloud radiative forcing at Summit, tied with the advection of moisture. The primary feature linked to positively anomalous cloud radiative forcing (CRF) values is a deep cyclonic system in Baffin Bay, to the west of the ice sheet. Using detailed measurements from the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) experiment, reveals specific cloud properties have a direct relationship with positive CRF values and thus surface warming at Summit Station. Finally, the days leading up to the July 2012 extreme melt event are mapped with the SOM classification and it is shown that the melt event corresponds with prolonged ice sheet warming resulting from circulation patterns causing an unusually extended period of anomalously positive CRF.