Historical Increase in Autumn and Winter Cyclone‐Associated Precipitation Over the Arctic Ocean Driven Primarily by Enhanced Arctic Evaporation

Abstract What is the relative importance of variability in local evaporation versus moisture convergence from lower latitudes to changes in autumn/winter Arctic Ocean precipitation? Past research has offered sometimes contradictory answers. Here we offer some resolution to this question by addressing two research gaps. First, recognizing that most studies ascribing greater local evaporation (and sea ice loss) to increasing Arctic precipitation have been conducted with climate models, we turn to the ERA5 atmospheric reanalysis to examine a 46‐year record (1979–2024) of Arctic precipitation and related moisture, circulation, and radiation variables. Second, we focus attention on precipitation specifically associated with extratropical cyclones, offering insights beyond what can be gained by only looking at Arctic‐wide seasonal averages. We find that cyclone‐associated precipitation (CAP) over the Arctic Ocean primarily changes in the cold season (October–March), increasing by 5.3% per decade. Spatial patterns of positive CAP trends along the margins of the Arctic Ocean align closely with patterns of sea ice loss and enhanced local evaporation and typically exhibit negative trends in moisture convergence. Conversely, the area around the North Pole, with no significant sea ice loss, has experienced more modest precipitation increases driven by enhanced moisture convergence. For the Arctic Ocean overall, 78% of the increase in cold‐season CAP is explained by the increase in local evaporation. A complementary Lagrangian moisture budget analysis of migratory cyclones yields more uncertainty but also shows enhanced local evaporation as the greatest driver of enhanced cold season precipitation.