Atmospheric moisture intrusion into the Arctic: sources, impact, and trends

Atmospheric water vapor plays an enormously important role in the water cycle and energy budget of the Arctic. Water vapor in the Arctic also participates in many important feedback mechanisms influencing the climate response to forcing agents and the Arctic amplification. In this study, we conduct analysis of atmospheric moisture transport into the Arctic based on reanalysis products and CMIP6 model simulations. We are particularly interested in the episodic atmospheric-river-like features (AR or moisture intrusion) that play an important role in delivering water to the Arctic. Based on the method of using column-integrated meridional vapor transport for characterizing AR events, we find that the mean AR frequency peaks in the Atlantic sector in all seasons except that it’s more zonally widespread in summer. An increasing trend in the Arctic AR frequency in the recent decades identified from ERA5 can be captured by few CMIP6 models. The historical Arctic AR frequency, sea ice concentration and Arctic warming are highly correlated. Atmospheric circulation patterns that drive the interannual and decadal Arctic AR variation contribute substantially to the historical Arctic warming. We also use the Community Earth System Model (CESM), equipped with a water tagging capability, to quantify contributions of surface evaporation within the Arctic versus from lower-latitude regions as a source of water to the Arctic and characterize moisture transport pathways that control the Arctic water vapor distribution.