Rainfall on the Greenland Ice Sheet: Present-Day Climatology From a High-Resolution Non-Hydrostatic Polar Regional Climate Model

Greenland ice sheet rainfall is expected to increase under a warming climate. Yet, there have been no active long-term in-situ rainfall records on the ice sheet due to observational difficulties. Here, we utilize the state-of-the-art 5 km polar non-hydrostatic regional climate model NHM-SMAP to evaluate the ice sheet's rainfall over 40 years (1980-2019). The largest trends include a fourfold increase in annual rainfall for the northwestern ice sheet; 3.1 Gt year⁻¹ or 12 mm m⁻² year⁻¹. September ice-sheet-wide rainfall amount and intensity increase by 7.5 Gt month⁻¹ and 20.8 mm h⁻¹ year⁻¹. In the last two decades, the increasing September maximum hourly rainfall rate exceeded 50 mm h⁻¹ six times. The increased surface water delivery has numerous implications, including for snow metamorphism and ice flow dynamics.