Evaluation of CloudSat snowfall rate profiles by a comparison with in situ micro-rain radar observations in East Antarctica

Abstract

Abstract. The Antarctic continent is a vast desert and is the coldest and the most unknown area on Earth. It contains the Antarctic ice sheet, the largest continental water reservoir on Earth that could be affected by the current global warming, leading to sea level rise. The only significant supply of ice is through precipitation, which can be observed from the surface and from space. Remote-sensing observations of the coastal regions and the inner continent using CloudSat radar give an estimated rate of snowfall but with uncertainties twice as large as each single measured value, whereas climate models give a range from half to twice the space–time-averaged observations. The aim of this study is the evaluation of the vertical precipitation rate profiles of CloudSat radar by comparison with two surface-based micro-rain radars (MRRs), located at the coastal French Dumont d'Urville station and at the Belgian Princess Elisabeth station located in the Dronning Maud Land escarpment zone. This in turn leads to a better understanding and reassessment of CloudSat uncertainties. We compared a total of four precipitation events, two per station, when CloudSat overpassed within 10 km of the station and we compared these two different datasets at each vertical level. The correlation between both datasets is near-perfect, even though climatic and geographic conditions are different for the two stations. Using different CloudSat and MRR vertical levels, we obtain 10 km space-scale and short-timescale (a few seconds) CloudSat uncertainties from −13 % up to +22 %. This confirms the robustness of the CloudSat retrievals of snowfall over Antarctica above the blind zone and justifies further analyses of this dataset.

Evaluation of CloudSat's Cloud‐Profiling Radar for Mapping Snowfall Rates Across the Greenland Ice Sheet

“…In particular, CloudSat measured the intensity of two snowfall events (0.44 and 0.65 mm/hr) within ± 9% as compared to the precipitation gauge at KAN-B. These findings corroborate Lemonnier et al (2019), who demonstrated that CloudSat measured snowfall rates of individual events with accuracies of −13 to +22% in comparison to microrain radar instruments located at the Dumont d'Urville and Princess Elisabeth stations in Antarctica. However, at Summit, we find that POSS observed 117 more snowfall events than CloudSat.…”

Evaluation of Synoptic Snowfall on the Antarctic Ice Sheet Based on CloudSat, In-Situ Observations and Atmospheric Reanalysis Datasets

“…We reconstructed snowfall on the AIS at new temporal resolutions based on the CloudSat 2C-SNOW-PROFILE dataset. Monthly AWS snow accumulation was compared with monthly CloudSat snowfall and MRR was compared with instantaneous CloudSat snowfall in the previous studies [17,18]. Unlike previous studies [17,18], daily snow accumulation and extreme snow accumulation events were compared with synoptic CloudSat snowfall.…”

“…Monthly AWS snow accumulation was compared with monthly CloudSat snowfall and MRR was compared with instantaneous CloudSat snowfall in the previous studies [17,18]. Unlike previous studies [17,18], daily snow accumulation and extreme snow accumulation events were compared with synoptic CloudSat snowfall. We also compared the CloudSat snowfall with the ERA5 snowfall to evaluate the synoptic performance of the new European Centre for Medium-Range Weather Forecasts (ECMWF) climate reanalysis dataset [32], which has now fully replaced the ERA-Interim dataset [33].…”

“…Monthly CloudSat snowfall data have been examined by snow accumulation measurements from automatic weather stations (AWSs) [17]. However, there are few attempts to use ground-based measurements (e.g., micro-rain radar (MRR)) to examine the CloudSat snowfall over the AIS at shorter timescales [5,18,19] because there is currently no precipitation gauge network and few continuous snowfall measurements for the AIS [5,20]. CloudSat provides a possible way to solve these problems.CloudSat has a 16-day repeat period covering regions from 82 • N to 82 • S. The density of radar footprints increases with the rise of latitude.…”

“…It is possible that CloudSat could provide a reliable database of snowfall observations at daily or multi-day resolutions in some areas of the AIS.MRR measures vertical profiles and uses the radar reflectivity-snowfall rate relationship to acquire the precipitation rate based on the microphysical properties of snowfall [21]. Lemonnier et al (2019) have compared CloudSat snowfall retrievals with MRR observations at two stations in Antarctica (Dumont d'Urville and Princess Elisabeth) [18]. Their results suggest that MRR has an advantage because it measures precipitation/snowfall directly and is less affected by wind than the acoustic depth gauges (ADGs) installed at AWSs.…”