Seasonal mass variations show timing and magnitude of meltwater storage in the Greenland Ice Sheet

摘要: Abstract. The Greenland Ice Sheet (GrIS) is currently losing ice mass. In order to accurately predict future sea level rise, the mechanisms driving observed mass loss must be better understood. Here, we combine data from satellite gravimetry mission Gravity Recovery and Climate Experiment (GRACE), surface mass balance (SMB) output of Regional Atmospheric Model v. 2 (RACMO2), discharge estimates to analyze mass budget Greenland at various temporal spatial scales. We find that mean rate mass variations in observed by GRACE was between − 277 and 269 Gt yr −1 2003–2012. This estimate consistent with sum (i.e., - 304 ± 126  Gt yr ) individual contributions – (SMB, 216±122 ( 520±31 previous studies. further identify a seasonal anomaly throughout record peaks July at 80–120 Gt which interpret due a combination englacial and subglacial water storage generated summer surface melting. The robustness this demonstrated using both different GRACE-based solutions different meltwater runoff (namely, RACMO2.3, SNOWPACK, MAR3.9). Meltwater storage in sheet occurs primarily high-accumulation regions southeast northwest parts Greenland. Analysis of seasonal variations outlet glacier shows contribution of signal minor (at only few gigatonnes) does not explain seasonal differences total mass SMB signals. With improved quantification storage at scale, highlight its importance for understanding glacio-hydrological processes their mass variability.