C054-0013
Satellite Observations of Greenland Ice Sheet Snowfall: Connecting Cloud Phase, Snowfall Rates, and Regional Atmospheric Circulation

Tuesday, 15 December 2020
Poster
Elin McIlhattan1, Claire Pettersen2, Norman Wood2 and Tristan L'Ecuyer3, (1)University of Wisconsin Madison, Madison, WI, United States, (2)University of Wisconsin Madison, Space Science and Engineering Center, Madison, WI, United States, (3)University of Wisconsin, Department of Atmospheric and Oceanic Sciences, Madison, WI, United States
Abstract:
Snowfall affects the surface mass balance of the Greenland Ice Sheet (GrIS) in two important ways, it adds mass to the surface and it increases the surface albedo, which can in turn inhibit melt. However, the remote nature and harsh conditions of the GrIS have resulted in a lack of large scale, long term snowfall observations. A better understanding of snowfall frequency, rate, duration, and connection to large-scale atmospheric patterns is needed in order for the drivers of current surface mass balance variability to be well understood and reliable estimates to be made for the future. A previous study used ground based observations from Summit Station, Greenland to partition snowfall events into two regimes: snowfall associated with ice clouds and snowfall associated with clouds containing super-cooled liquid water. That study found markedly different snowfall characteristics and dynamical drivers for the two regimes observed at Summit.

In this work, we use satellite data to identify snowfall events over the full GrIS for the period of 2007-2016 and partition them by snowfall regime. Two satellite instruments aboard NASA's A-Train constellation make this partitioning possible: CALIPSO's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is used to discern the phase of a cloud layer and collocated measurements from CloudSat's Cloud Profiling Radar (CPR) are used to determine whether the cloud is producing snow. Over the full GrIS, the majority of observed annual snowfall (70 %) comes from ice clouds, and ice clouds produce ~80% of the total estimated 399 Gt yr-1 accumulation. Snowfall associated with liquid containing clouds are most prevalent in summer and represent close to half (45 %) of all summertime snow frequency. Leveraging ERA5 reanalyses, we find that snowfall events from ice phase clouds are associated with cyclone activity while snowfall events from mixed-phase clouds generally occur under large scale anomalously high geopotential heights over the GrIS. In this presentation, we will detail our findings and discuss their implications and limitations.

<< Previous Abstract | Next Abstract >>