Understanding the Climatology and Characteristics of Arctic Moisture Intrusions

Moisture and heat transport into the Arctic play important roles in modulating the local climate and Arctic sea ice variability. Moisture intrusions, the transport of extreme moisture channels into the Arctic, can perturb the surface energy balance and sea ice mass balance through radiative changes, triggering melt and inhibiting sea ice growth. Observations have shown increases in both temperature and moisture content in the Arctic in recent decades. This study presents a tracking algorithm to identify and track moisture intrusion events into the Arctic based on ERA5 total column water vapor and northward water vapor flux. The resulting climatology of Arctic moisture intrusions and their characteristics from 1979 to 2022 reveals an average of 228 events annually with the highest frequency during the summer. Intrusion events originate more frequently in the North Pacific (NP) than the North Atlantic (NA), however, NA intrusions are larger, more intense, and longer lasting than NP events. Therefore the NA (79.75 days) experiences more days of extreme moisture intrusion throughout the year than the NP (45.75 days). Arctic wide intrusion events are also observed to have increasing trends in size (+20%), intensity (+15 days), and max latitude (+4.3) between 1979 and 2022. This moisture intrusion dataset furthers our understanding of these extreme events and allow us to assess their immediate and longer lasting impacts on the Arctic climate system.