Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021

Abstract. Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding the evolution combined ice and air content within firn column. In absence suitable techniques observe changes column across entirety sheet, processes are typically modeled. Here, we present new simulations over Greenland Antarctic sheets (GrIS AIS) using Community Firn Model atmospheric reanalysis variables for more than four decades. A data set 250 measured depth–density profiles from both provides basis calibration dry-snow densification scheme. The resulting scheme results in a reduction rate densification, relative commonly used semi-empirical model, through decreased dependence on accumulation rate, proxy overburden stress. 1980–2020 modeled runoff, when with MERRA-2, generates realistic mean integrated surface balance values (+390 Gt yr−1) (+2612 compared published model-ensemble means. We find that seasonal associated average approximately 2.5 times larger those fluxes AIS 1.5 GrIS; however, averaged multiple years, air-volume fluctuations comparable magnitudes. Between 1996 2019, Ice Sheet lost nearly 5 % its content, indicating total meltwater retention capability. Nearly all (94 %) produced is retained infiltration refreezing.