The role of large-scale atmospheric patterns for recent warming periods in Greenland from 1900–2015

Abstract

Large-scale atmospheric 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 and impact of large-scale atmospheric patterns during two distinct warming periods of the recent past that we identify objectively in climatological data. The first warming period (1922–1932) shows an average air temperature anomaly increase of 2.9 °C across all stations considered for this study. The second period (1993–2007) exhibits a comparable warming of 3.1 °C. We apply Self-Organizing Maps to cluster the geopotential height of the 500 hPa pressure level using 20CRv3 reanalysis data, characterizing prevalent large-scale atmospheric patterns and investigating their occurrence, persistence, and effects on air temperature anomalies at our study site (Qaamarujup Sermia) in West Greenland. While the overall warming magnitude is similar, the distribution of circulation patterns differs slightly but significantly between the two periods and from the full period (1900–2015). The first warming period features more frequent cyclonic patterns, while the second warming period is characterized by increased south westerly advection, indicating a shift in circulation patterns. Negative temperature anomalies are linked to northerly or downslope flow, whereas southerly advection consistently drives positive anomalies. Zonal westerly flow – the most common pattern (47 % of days) – is associated with near-zero average anomalies but includes both warm and cold extremes. The warmest days in winter, spring, and autumn are linked to southerly flow, while summer warm extremes and cold extremes across all seasons occur predominantly under zonal conditions. Importantly, the relationship between circulation patterns and local temperature anomalies remains stable over time. This study emphasizes the critical role of changes in large-scale atmospheric patterns for understanding Greenland under climate warming.