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Abstract:
Bering Strait transport is a key source of heat, freshwater, and nutrients for the Arctic. Moored observations indicate that transport has been increasing over the last decades. Recently, Danielson et al. (2020) have proposed a feedback mechanism by which increased sea surface temperatures (SST) in the Chukchi Sea would drive stronger ocean to atmosphere heat fluxes in fall, leading to anomalously strong winds to the North over the Bering Strait, and thus increased Bering Strait heat and volume fluxes. We investigate this hypothesis with a combination of observations and modeling. First, we inspect reanalysis products to interrogate whether the observed trends support the proposed feedback mechanism. Next we investigate the response of an ocean model to reanalysis forcing, looking for evidence of whether this response can be detected for such simulations. Results indicate that the proposed increase in northward wind stress over the Bering Strait is highly localized in space and only significant in October, despite robust trends in SST and surface heat fluxes. Simulations do not replicate the positive trend in Bering Strait volume transport and raise the question as to whether increases in local winds are indeed responsible? To test this hypothesis, the same ocean model is forced with additional localized northward wind perturbations to determine the strength and persistence of surface forcing required to reproduce the observed trend in Bering Strait ocean transport. The transport response to a range of wind perturbation experiments will be presented and the limitations and implications of this research will be discussed.
