An empirical algorithm to map perennial firn aquifers and ice slabs within the Greenland Ice Sheet using satellite L-band microwave radiometry

Abstract. Perennial firn aquifers are subsurface meltwater reservoirs consisting of a meters-thick water-saturated layer that can form on spatial scales as large tens kilometers. They have been observed within the percolation facies glaciated regions experiencing intense seasonal surface melting and high snow accumulation. Widespread perennial identified Greenland Ice Sheet (GrIS) via field expeditions, airborne ice-penetrating radar surveys, satellite microwave sensors. In contrast, ice slabs nearly continuous layers also kilometers result sequentially refreezing following multiple seasons. but in areas where accumulation is at least 25 % lower compared to aquifer areas. recently GrIS expeditions specifically typically do not form. However, yet be from space. Together, these two sheet features represent distinct, related, sub-facies broader defined primarily by differences accumulation, which influences englacial hydrology thermal characteristics depth. Here, for first time, we use enhanced-resolution vertically polarized L-band brightness temperature (TVB) imagery (2015–2019) generated using observations collected over NASA's Soil Moisture Active Passive (SMAP) map slab together hydrological system. We an empirical algorithm previously developed extent Greenland's fitting exponentially decreasing temporal signatures set sigmoidal curves. This recalibrated surveys Operation IceBridge (OIB) campaigns (2010–2017). Our SMAP-derived maps show between 2015 2019, extended 64 000 km2, 76 km2. Combined together, equivalent 24 GrIS. As climate continues warm, will increase extent, intensity, duration. Quantifying possible rapid expansion radiometry has significant implications understanding ice-sheet-wide variability may drive meltwater-induced hydrofracturing accelerated flow well high-elevation runoff impact mass balance stability