Intensification of the Atlantic Water Supply to the Arctic Ocean Through Fram Strait Induced by Arctic Sea Ice Decline

Qiang Wang,Xuezhu Wang,Nikolay Koldunov,Thomas Jung,Claudia Wekerle,Wilken‐Jon Von Appen,Dmitry Sidorenko,Dmitry Sein,Sergey Danilov

doi:10.1029/2019gl086682

Abstract

AbstractSubstantial changes have occurred in the Arctic Ocean in the last decades. Not only sea ice has retreated significantly, but also the ocean at middepth showed a warming tendency. By using simulations we identified a mechanism that intensifies the upward trend in ocean heat supply to the Arctic Ocean through Fram Strait. The reduction in sea ice export through Fram Strait induced by Arctic sea ice decline increases the salinity in the Greenland Sea, which lowers the sea surface height and strengthens the cyclonic gyre circulation in the Nordic Seas. The Atlantic Water volume transport to the Nordic Seas and Arctic Ocean is consequently strengthened. This enhances the warming trend of the Arctic Atlantic Water layer, potentially contributing to the Arctic “Atlantification.” Our study suggests that the Nordic Seas can play the role of a switchyard to influence the heat budget of the Arctic Ocean.

Highlights

The Arctic Ocean is located at the northern end of the North Atlantic Overturning Circulation (AMOC), which carries ocean heat in the Atlantic Water (AW) from the North Atlantic through the Nordic Seas into the Arctic Ocean (Figure 1a)
We found that the Arctic sea ice decline and the resultant reduction in sea ice volume export change the ocean salinity, sea surface height (SSH) and the cyclonic gyre circulation in the Greenland Sea and Nordic Seas, which strengthens the AW volume and heat supply to the Arctic Ocean
Observations show that the AW layer at Fram Strait and downstream inside the Arctic Ocean has become warmer (e.g., Beszczynska-Moeller et al, 2012; Polyakov et al, 2013)

Summary

Introduction

The Arctic Ocean is located at the northern end of the North Atlantic Overturning Circulation (AMOC), which carries ocean heat in the Atlantic Water (AW) from the North Atlantic through the Nordic Seas into the Arctic Ocean (Figure 1a). The Arctic sea ice is isolated from the AW layer by the halocline, the ocean heat can penetrate to the surface and induce sea ice basal melting in certain regions (Carmack et al, 2015; Dmitrenko et al, 2014; Ivanov et al, 2012; Onarheim et al, 2014; Polyakov et al, 2010). Dynamical processes responsible for the recent upward trends in AW temperature and ocean heat transport at Fram Strait are not fully understood. We found that the Arctic sea ice decline and the resultant reduction in sea ice volume export change the ocean salinity, sea surface height (SSH) and the cyclonic gyre circulation in the Greenland Sea and Nordic Seas, which strengthens the AW volume and heat supply to the Arctic Ocean

Model Setups

Results

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Conclusions