How much snow falls on the Antarctic ice sheet?

Climate models predict Antarctic precipitation to increase during the 21st century, but their present day Antarctic precipitation differs. A model-independent climatology of the Antarctic precipitation characteristics, such as snowfall rates and frequency, is needed to assess the models, but it is not yet available. Satellite observations of precipitation by active sensors has been possible in the polar regions since the launch of CloudSat in 2006. Here, we use two CloudSat products to generate the first multi-year, model-independent climatology of Antarctic precipitation. The first product is used to determine the frequency and the phase of precipitation, while the second product is used to assess the snowfall rate. The mean snowfall rate from August 2006 to April 2011 is 171mm year(-1) over the Antarctic ice sheet, north of 82 degrees S. While uncertainties on individual precipitation retrievals from CloudSat data are potentially large, the mean uncertainty should be much smaller, but cannot be easily estimated. There are no in situ measurements of Antarctic precipitation to directly assess the new climatology. However, distributions of both precipitation occurrences and rates generally agree with the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data set, the production of which is constrained by various in situ and satellite observations, but does not use any data from CloudSat. The new data set thus offers unprecedented capability to quantitatively assess Antarctic precipitation statistics and rates in climate models.