Summer atmospheric rivers (ARs) reaching high latitudes contribute significantly to Arctic moisture transport. This transport has shown long-term changes not fully explained by anthropogenic forcing alone. Observational analysis and model experiments reveal that low-frequency, large-scale circulation changes in the Arctic play a crucial role in regulating AR activity, leading to a recent increase. This trend in summertime AR activity contributes to approximately 36% of the increasing trend of atmospheric summer moisture over the entire Arctic since 1979 and over half in areas like western Greenland, northern Europe, and eastern Siberia. This suggests AR activity, often seen as stochastic, is a vital mechanism in regulating long-term Arctic moisture variability.

Zhibiao Wang, Qinghua Ding, Renguang Wu, Thomas J. Ballinger, Bin Guan, Deniz Bozkurt, Deanna Nash, Ian Baxter, Dániel Topál, Zhe Li, Gang Huang, Wen Chen, Shangfeng Chen, Xi Cao, Zhang Chen