Cloud, Seasonal, and Blocking Influences on Snowfall over the Greenland Ice Sheet
Future projections of Greenland Ice Sheet (GrIS) mass balance and associated sea level rise have significant uncertainty, in part due to a lack of observations of and information about precipitation processes. In the presented work, Arctic snowfall regimes are categorized by the presence or absence of condensed liquid water in the associated clouds. This classification scheme reveals two distinct, primary regimes of snowfall over the GrIS: one originating from fully glaciated ice clouds and the other from mixed-phase clouds. Five years of co-located, multi-instrument data from the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) suite are used to assess cloud characteristics, meteorological properties, and large-scale circulation patterns associated with each snowfall regime. Further work utilizes the active sensors aboard NASA A-Train satellites to expand this analysis over the entire GrIS. A-Train derived data products are compared to composite case studies over Summit Station to assess results from the ground-based and space-borne sensors. This work is then expanded to examine the full GrIS, dividing snowfall events into the two regimes and documenting their frequency spatially and by season, and approximating the snowfall rate and accumulation. Finally, investigations of high impact snowfall events at Summit Station illuminate seasonal relationships with atmospheric blocking and North Atlantic cyclones. There is a causal relationship between statistically significant anomalous blocking and the advection of warm, moist air over the GrIS and the snowfall regimes observed at Summit Station.
