Arctic sea ice has been declining rapidly in recent decades due to enhanced warming, leading to increasingly intense storms in the region. Atmospheric Rivers (ARs) are narrow, transient corridors of strong horizontal water vapor transport typically associated with the cold front of an extratropical cyclone. ARs have the potential to drive sea-ice changes in the Arctic through rain and heat convergence (net sea-ice loss) or snowfall (net sea-ice gain). However, we still lack an understanding of how ARs are changing in a warming climate and the impacts of these changes on sea-ice.
We use an Atmospheric River Detection and Tracking algorithm (ARDT) based on meridional integrated vapor transport to detect Arctic ARs in MERRA2 Reanalysis. The monthly climatology of the ARs shows more ARs in winter compared to summer. Distinct AR hotspots are more prominent during winter (DJFM) over Russia and the Atlantic and Pacific sectors. A net daily sea-ice loss of 5 to 15 sq km/day during winter is observed in the regions of West Greenland and the Barents and Kara Seas for ARs lasting longer than 12 hours. We also find that the longer duration ARs cause a progressively larger sea-ice loss. Hence it is crucial to investigate ARs and their impacts on sea-ice in a warming climate.
We use historical simulations of the Community Earth System Model, Version 2 (CESM2), to evaluate the model performance in simulating intense Arctic ARs. We show that using the same ARDT the 40 ensemble members perform well in capturing the general AR patterns and distinct hotspots compared with MERRA2 for 1980-2015. AR occurrences across 40 historical and 50 future realizations (1850-2100) will help us determine the effects of climate change on AR characteristics, their impacts on sea-ice, and precipitation.