The Critical Role of Euro-Atlantic Blocking in Promoting Snowfall in Central Greenland

This study examines the impacts of atmospheric blocking across the Euro-Atlantic region on precipitation processes over the central Greenland Ice Sheet (GrIS). Enhanced precipitation in the central GrIS is related to Euro-Atlantic blocking with anomalous blocking present during 84 % of June, July, August (JJA) and 78 % of September, October, November (SON) snowfall events. JJA snowfall events are linked to a persistent blocking anticyclone over southern Greenland, while SON snowfall events are connected to a rapidly developing blocking anticyclone over the Nordic Seas and blocking frequency anomalies over northern Europe. The JJA precipitation is produced primarily by Arctic mixed-phase clouds (88 %) and there are positive temperature and water vapor anomalies to the west and south of Greenland on the western flank of the blocking anticyclone. Additionally, the zonal pattern of the highest values of water vapor transport south of Greenland indicate a southern shift North Atlantic storm track during the JJA enhanced precipitation events. The majority of the SON precipitation is produced by deep, fully glaciated ice clouds (85 %), and anomalous positive temperature and water vapor to the east and southeast of Greenland are transported along the western flank of the blocking anticyclone. During SON snowfall events, the North Atlantic storm track is blocked and storms are being steered towards the southeast coast of Greenland, directly interacting with the GrIS from the southeast.