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Bering Strait is the only ocean gateway connecting the Pacific and Arctic oceans. The ∼1 Sv northward flow of Pacific water through the strait to the Arctic Ocean has been increasing by ∼0.01 Sv/yr since 1990. Monthly dynamic ocean topography (DOT), wind, and sea‐ice data at Bering Strait are analyzed in context with the long‐term record of flow through the strait to investigate local drivers. Ocean transport is found to be proportional to the across‐strait slope in DOT, suggesting some component of the flow is in geostrophic balance. Along‐strait ocean surface stresses, which modulate the across‐strait DOT slope via Ekman transport, are analyzed in the presence of a seasonally varying ice cover. It is shown that northward interior ocean flow under sea ice in winter results in southward surface stresses, and westward Ekman transport that slows the geostrophic component of the northward ocean flow. As the number of open water days local to Bering Strait increase each year, we find no trend in the annual mean surface stress, that is, the loss of sea ice is not leading to increased northward wind stress input that would enhance northward ocean flow. This analysis is consistent with the theory that changes in both the atmosphere and ocean non‐local to Bering Strait are likely driving the increased transport from the Pacific into the Arctic via Bering Strait.
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Arctic and Sub‐Arctic Mechanisms Explaining Observed Increasing Northward Flow Through the Bering Strait and Why Models May Be Getting It Wrong
Abstract The Pacific oceanic input to the Arctic via the Bering Strait (important for western Arctic ice retreat, water properties, and nutrient supply) has been increasing for three decades. Using satellite Ocean Bottom Pressure (OBP) and Dynamic Ocean Topography (DOT) data, we show that long‐term trends in mooring data for a well‐sampled sub‐period (2003–2014) relate to summer OBP and DOT drop in the Arctic's East Siberian Sea (ESS), in turn caused by stronger westward ESS winds, and increased fall westward winds in the Bering Sea. OBP/DOT differences imply strong (0.17 psu/year) ESS salinization, likely caused by hitherto unappreciated increased Pacific inflow to that region. We find ESS OBP trends are (erroneously) reversed in older data versions, and estimate that ESS salinization may significantly mediate Bering Strait flow increase. These facts may explain why models assimilating older OBP data, or with erroneous Bering Strait salinities, fail to simulate observed Bering Strait flow increase.
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- PAR ID:
- 10490047
- Publisher / Repository:
- AGU
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 50
- Issue:
- 24
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2023GL104697
