Observed increases in Bering Strait oceanic fluxes from the Pacific to the Arctic from 2001 to 2011 and their impacts on the Arctic Ocean water column

Abstract

Mooring data indicate the Bering Strait throughflow increases ∼50% from 2001 (∼0.7 Sv) to 2011 (∼1.1 Sv), driving heat and freshwater flux increases. Increase in the Pacific‐Arctic pressure‐head explains two‐thirds of the change, the rest being attributable to weaker local winds. The 2011 heat flux (∼5 × 1020J) approaches the previous record high (2007) due to transport increases and warmer lower layer (LL) temperatures, despite surface temperature (SST) cooling. In the last decade, warmer LL waters arrive earlier (1.6 ± 1.1 days/yr), though winds and SST are typical for recent decades. Maximum summer salinities, likely set in the Bering Sea, remain remarkably constant (∼33.1 psu) over the decade, elucidating the stable salinity of the western Arctic cold halocline. Despite this, freshwater flux variability (strongly driven by transport) exceeds variability in other Arctic freshwater sources. Remote data (winds, SST) prove insufficient for quantifying variability, indicating interannual change can still only be assessed by in situ year‐round measurements.