The role of atmospheric large-scale patterns for recent warming periods in Greenland

Abstract. Atmospheric large-scale patterns strongly determine Greenland’s regional climate through air mass advection and local weather conditions, making them essential to understand atmospheric variability. This study analyses the occurrence of atmospheric large-scale patterns during two distinct warming periods of the recent past that we identify objectively in climatological data. The first warming period lasted from 1922 to 1932 and an average air temperature increase of 2.9 °C across all stations considered for this study. The second warming period lasted from 1993 to 2007 and had an average warming of 3.1 °C. We apply Self-Organizing Maps as a clustering technique based on the geopotential height of the 500 hPa pressure level using 20CRv3 reanalysis data to characterize prevalent atmospheric large-scale patterns and investigate their occurrence, persistence, and effects on air temperature anomalies at our study site (Qaamarujup Sermia) in West Greenland. Both warming periods show similar overall air temperature anomalies. However, the distribution of large-scale atmospheric patterns differs significantly, while the relationship between atmospheric large-scale patterns and local air temperature seems to be constant in time. This suggests that variations in Greenland’s warming are influenced by shifts in atmospheric circulation. This study emphasizes the critical role of changes in atmospheric large-scale patterns for understanding Greenland’s warming periods.