Mechanisms Driving the Interannual Variability of the Bering Strait Throughflow

Wenhao Zhang,Xuezhu Wang,Sergey Danilov,Qiang Wang

doi:10.1029/2019jc015308

Abstract

AbstractThe Bering Strait throughflow has important implications for the Arctic freshwater, heat, and nutrients. By keeping the interannual variabilities of the atmospheric forcing only inside or outside the Arctic Ocean in numerical simulations, we can quantify their relative contributions to the interannual variability of the throughflow. We found that winds play a much more important role for the throughflow interannual variability than buoyancy forcing. Winds over the western Arctic Ocean and North Pacific determine the direction of Ekman transport, thus changing the sea surface height gradient between the two basins, and consequently influencing the volume transport strength. Although winds over the two basins are similarly important for the variance of ocean volume transport, the North Pacific winds cause stronger variability in freshwater and heat transports through modifying the inflow temperature and salinity. After 1994, winds over the western Arctic Ocean explain a larger part of the variability of Bering Strait volume transport than the winds outside the Arctic Ocean.

Highlights

The Bering Strait is the only oceanic linkage between the Pacific and Arctic Ocean (Figure 1a)
Numerical simulations were used to attribute the interannual variability of the Bering Strait inflow to atmospheric forcing in different regions
Our results indicate that the sea surface height (SSH) gradient between the Bering Sea and Arctic Ocean drives the variability of the Bering Strait inflow, consistent with previous studies (Coachman & Aagaard, 1988)

Summary

Introduction

The Bering Strait is the only oceanic linkage between the Pacific and Arctic Ocean (Figure 1a). It has been suggested that the Bering Strait inflow on annual to interannual time scales is primarily driven by the oceanic pressure difference between the Pacific and the Arctic Oceans (the so‐called pressure head), which is related to the sea surface height (SSH) gradient between the two basins, while the throughflow. Woodgate et al (2012) found that two thirds of the Bering Strait transport interannual variability can be attributed to the Pacific‐Arctic pressure head, while local wind stress explains the remaining one third of the transport variability. By using ocean bottom pressure observations, Peralta‐Ferriz and Woodgate (2017) suggested that the Bering Strait throughflow variability is predominantly driven from the Arctic in the period of observations, in particular by the SSH change in the East Siberian Sea, other forcings play a role depending on the season. The interannual variation of the atmospheric forcing only inside or outside the Arctic Ocean in the simulations, we are able to directly attribute the interannual variability of the throughflow

Model Setup and Methods

Results

Discussions and Conclusions