Variability in the Surface Energy Budget of the Greenland Ice Sheet and its relationship to the climatology of air trajectories over 40 years.

In the Arctic, the increase in atmospheric temperature is more than twice the global average. Changes in large-scale atmospheric circulation in the Arctic have led to changes in air-mass trajectories and synoptic variability which have been shown to affect local-scale meteorological conditions including radiative and turbulent heat fluxes. Understanding how these changes impact the surface energy budget of the Greenland Ice Sheet (GIS) is of particular interest as the GIS is a significant contributor to global sea level rise. In this study, we provide a climatology for air-mass back trajectories over Summit Station, Greenland and investigate the trend and variations in the surface energy budget associated with these back trajectories over 40 years. Using the Hybrid Single-Particle Lagrangian Inte­grated Trajectory model (HYSPLIT) and NCEP/NCAR Reanalysis data, 5-day isentropic back trajectories at 500 hpa are simulated for Summit Station, Greenland from 1979 to 2018. These 40 years of back trajectories are clustered by season in order to classify the major source regions and air-mass trajectories at the top of the Greenland Ice Sheet. The Reanalysis data are compared to in situ radiative flux observations at Summit Station Greenland. Correlation of the variability in these patterns with the radiative and turbulent heat fluxes at Summit Station provide understanding of how atmospheric circulation changes are driving important changes in the GIS surface energy budget.