Validating CloudSat-CPR retrievals for the estimation of snow accumulation in the Canadian Arctic

Abstract

Snow is a critical contributor to our global water and energy budget, with profound impacts for water resource availability, snow albedo feedback and flooding in cold regions. The vast size and remote nature of the Arctic present serious logistical and financial challenges to measuring snow over extended time periods. Satellite observations provided by the Cloud Profiling Radar (CPR) instrument-installed on the NASA satellite CloudSat-allow the retrieval of snowfall rates in high latitude regions, which have been used to estimate surface snow accumulation. In this study, a validation of CloudSat-derived terrestrial snow estimates is presented at four Environment and Climate Change Canada (ECCC) weather stations situated in the Arctic for the common period 2007-2015. Comparisons of monthly climatological snow accumulation show mean biases of less than 1.5 mm SWE annually. Monthly time series exhibit correlations above 0.5 and RMSE below 10 mm SWE at the two highest latitude stations (Eureka and Resolute Bay) with correlations falling below 0.5 south of 70 degrees N. CloudSat was also found to underestimate annual mean snow accumulation at the majority of sites, suggesting a potential negative bias in CloudSat's snowfall estimates, or underestimation related to sampling. These results imply that CloudSat can provide reliable estimates of snow accumulation across similar high latitude regions above 70 degrees N. Accurate space-based snowfall measurements provide new important observational perspectives of Arctic snow accumulation, which is a critical region for environmental monitoring in an era of global change.