Analysis of abrupt changes in the Arctic water budget as drivers of wintertime Arctic amplification

This study analyzes the Arctic water budget during the winter season (December ~ February) over a 43-year period from 1980 to 2022, with a focus on changes before and after the regime shift identified in 2004. Using ERA5 reanalysis data, we quantitatively analyze key hydrological components of total column water vapor, evaporation, precipitation, and meridional moisture flux. The Arctic is warming at approximately twice the rate of lower latitudes, and winter water vapor plays a particularly crucial role in this process. Our results reveal that the 2004 regime shift is characterized by significant increases in all of these measures. These changes, especially pronounced in the Barents and Kara Seas, suggest an intensification of the Arctic water cycle. The increase in water vapor has led to an increase in downward long-wave radiation, which strengthens the water vapor feedback mechanism and further contributes to regional warming. Spatial correlation analysis indicates a robust association among reduced sea ice cover, rising surface temperatures, and increased water vapor transport. These interlinked processes underscore the complexity of Arctic climate dynamics and the role of the water cycle in driving Arctic amplification. Moreover, the quantitative assessment provided in this study highlights the importance of considering changes in hydrological processes when projecting future Arctic climate change. The findings can serve as a valuable foundation for further research into the interactions among moisture transport, sea ice dynamics, and regional warming in the Arctic.