Climatology of Atmospheric Rivers and Associated Surface Warming in the Arctic: Regional Relationships With Teleconnection Patterns

Atmospheric river (AR) is one conspicuous pathway for poleward transport of moisture from lower latitudes. It could interact with Arctic warming and sea ice decline in the boreal winter. Through a detailed climatological study of ARs penetrating the Arctic, we highlight the evidence that teleconnection patterns modulate AR activities over several distinct Arctic regions. We analyzed the climate variability of an ensemble of six 3-hourly, 0.625° x 0.5°, integrated water vapor transport (IVT) or integrated water vapor (IWV) derived AR indices with 2-meter air temperature, horizontal winds, and calculated eddy kinetic energy (EKE) from NASA MERRA-2 between 1980 and 2019, along with NOAA outgoing longwave radiation, Hadley Centre sea surface temperature (SST), NASA CERES SYN1deg surface radiation, passive-microwave sea ice concentration (SIC) from Nimbus-7 SMMR and DMSP SSM/I-SSMIS, as well as NOAA Climate Prediction Center teleconnection indices. Due to data availability, the analysis with CERES and SIC were constrained to 2001-2019 and 1990-2019, respectively. The AR tracking and analysis were executed via distributed-parallel computing on a Hadoop cluster using the Divide & Recombine approach. We grouped the Arctic according to ARs monthly variability into four regions: the central Arctic (Region 1), Northeast America/Greenland (Region 2), Arctic Atlantic extending to the Eurasian continent (Region 3), Arctic Pacific covering the margins of the sea ice zone over Chukchi Sea (Region 4). The divisions were roughly consistent across the 6 AR indices. Results from the 95th_IVT-based index show that Arctic Oscillation (AO) influenced every region, with more than 68% of major AR events coinciding with AO. North Atlantic Oscillation (NAO) and Pacific North America also strongly modulated Region 1-3 and Region 4, respectively. The average of major AR events reveals that atmospheric circulation layout adjusts AR activity. Particularly, a dipole pattern with a combination of low and high pressure contrast favors AR activity. Accompanied by ARs penetration, strong EKE, enhanced warming and moistening, increased downward longwave radiation, associated SIC decline, and NAO and ENSO-related SST patterns were observed. The uncertainty of the results based on the 6 AR indices will be further quantified.