Moisture origin, transport pathways, and driving processes of intense wintertime moisture transport into the Arctic

Abstract. A substantial portion of the moisture transport into Arctic occurs in episodic, high-amplitude events with strong impacts on Arctic's climate system components such as sea ice. This study focuses origin moist-air intrusions during winter and examines sources, pathways, their linkage to driving large-scale circulation patterns. For that purpose, 597 intrusions, defined daily intense (exceeding 90th anomaly percentile) zonal mean polar cap (?70? N), are identified. Kinematic backward trajectories combined a Lagrangian source diagnostic then used pinpoint sources characterize airstreams accomplishing transport. The analyses show bulk transported these originates eastern North Atlantic an uptake maximum poleward 50? N. Trajectories further reveal inverse relationship between latitude level at which is injected cap, consistent ascent poleward-flowing air baroclinic atmosphere. Focusing (424 intrusions), we find lower tropospheric predominantly accomplished by two types airstreams: (i) cold, warmed moistened surface fluxes (ii) subsiding from mid-troposphere boundary layer. Both contribute about 36 % each total former accounts for most associated anomalously high frequency cyclones east Greenland (218 whereas latter more important presence atmospheric blocking over Scandinavia Ural Mountains (145 events). Long-range transport, accounting 17 dominates weak forcing weather systems (64 intrusions). Finally, mid-tropospheric invariably (diabatically) ascending central western Atlantic, including Gulf Stream front, roughly 10 In summary, our shows atmosphere result combination high-latitude or high-altitude origin, whose relative importance determined underlying (i.e., blocks).