A B S T R A C T : Understanding surface melt over the Greenland Ice Sheet (GrIS) is important for evaluating the effect of the changing global climate on humanity, and for forecasting sea level rise. We demonstrate a recently developed L-band passive microwave algorithm for the retrieval of snow liquid water and snow and firn density over the GrIS. The retrievals are performed using brightness temperatures from the ESA SMOS satellite. The density retrievals show potential for mapping the

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... rium line altitude of the ice sheet by determining where retrieved densities exceed typical seasonal snowpack density, thus indicating the presence of firn. We integrate snow liquid water retrievals over area and time to obtain water column maps and daily estimates of the surface liquid water present over Greenland. The integrated annual surface liquid water retrieved over the entire ice sheet compares on the same order as modeled estimates of total meltwater available in current literature.