Estimation of total surface and subsurface meltwater amounts across Greenland ice sheet

Greenland ice sheet (GrIS) melting has been a significant concern in the warming climate. Accurate quantification of total surface and subsurface meltwater amount across the pan-Greenland scale is crucial to understanding GrIS mass balance, thus better projecting global sea level rise. We used multi-year L-band observations from the NASA Soil Moisture Active Passive (SMAP) mission to quantify the GrIS surface and sub-surface meltwater amount and examine their spatiotemporal variability. We employed an empirical algorithm to detect surface and subsurface melt events. Then, we applied a physics-based retrieval algorithm to estimate the intensity and physical properties of the melt events. Finally, we validated the retrieval by meltwater derived from a locally calibrated energy balance model with in situ observations from the PROMICE automatic weather station (AWS) network. The retrieval and validation results are presented, which demonstrate generally a good agreement with the meltwater amounts derived from in situ observations.