Impact of cyclonic and anticyclonic activity on Greenland ice sheet surface mass balance variation during 1980–2013

The Greenland ice sheet (GrIS) has experienced dramatic ice loss during recent decades, but the drivers of the surface mass balance (SMB) variation remain unclear. From a dynamical perspective, extratropical cyclones and anticyclones are the major systems influencing Greenland weather conditions. Seasonal cyclonic and anticyclonic activities have been quantified for the area of 50°–90°N, 80°W–10°E during 1980–2013. Based on a singular value decomposition (SVD) analysis, we investigated the role of synoptic scale cyclonic and anticyclonic activities in determining snow accumulation (SA) and surface air temperature (SAT). Thus, the SA-driven and melt-driven SMB variability has been determined. SA-related synoptic patterns identified from the leading and the second SVD modes explain up to 80% of the inter-annual SMB variance, especially in southern and northwestern Greenland, where we found the largest and second largest amount of annual SA. SAT-related patterns account for up to 80% of the inter-annual SMB variation along the west and northwest coast of Greenland, where significant surface mass loss has been observed over the last decades. It should be noted that the negative phase of the SA-related pattern derived from the first SVD mode in June-July-August and the positive phase of the SAT-related (anti)cyclonic patterns have occurred more frequently since 2005, meaning that the phase change of these patterns has made a major contribution to the accelerated GrIS surface ice loss during recent years.