Pathways of meridional atmospheric moisture transport in the central Arctic

Abstract

Atmospheric moisture transport plays an important role in latent heat release and hydrologic interactions in the Arctic. In recent years, with the rapid decline in sea ice, this transport has changed. Here, we calculated the vertically integrated atmospheric moisture meridional transport (AMTv) from two global reanalysis datasets, from 1979–2015, and found moisture pathways into the central Arctic. Four stable pathways showed an occurrence frequency greater than 70%, and these pathways exhibited a perennial seasonal pattern in the atmosphere above the Laptev Sea Pathway (LSP), Canadian Arctic Archipelago Pathway (CAAP), both sides of the Greenland plateau. Another seasonal pathway appeared above the east of the Chukchi Sea (CSP) during the melting/freezing months (March to September). Through these pathways, AMTv contributed a total moisture exchange of 60%–80%—averaged over a 75°N circle—and focused on the low troposphere. Transports across the LSP, CSP and CAAP pathways likely create an enclosed moisture route. Meridional moisture fluxes are intensified in the Pacific sector of Arctic (PSA), especially during melting/freezing months. AMTv interannual variabilities are illustrated mainly in the Laptev Sea and the east Greenland pathway. Results indicate that accompanying a tendency for a stronger Beaufort Sea High in this sea level pressure field, AMTv through PSA pathways, switched from output to input, and approximately 960 km3 of equivalent liquid water was transferred into the central Arctic during each decade. The detrended AMTv increment is highly correlated with the rapid decline of old ice areas (correlation coefficient is −0.78) for their synchronous fluctuations in the 1980s and the last decade.