التفاصيل البيبلوغرافية
| العنوان: |
Pacific‐Arctic Connections: Assessing Flow Through Bering Strait in Context With Dynamic Ocean Topography and Surface Stress. |
| المؤلفون: |
Margevich, Annika, Timmermans, Mary‐Louise, Danielson, Seth |
| المصدر: |
Journal of Geophysical Research. Oceans; Aug2024, Vol. 129 Issue 8, p1-13, 13p |
| مصطلحات موضوعية: |
OCEAN surface topography, FRESH water, TOPOGRAPHY, STRAITS, OCEAN |
| مستخلص: |
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. Plain Language Summary: Bering Strait is a narrow waterway, 50 m deep and 85 km wide, between Alaska and Russia that allows relatively warmer and fresher Pacific water to flow into the Arctic Ocean. The volume of water entering the Arctic through Bering Strait has increased approximately 30% since 1990. It is unclear what processes are responsible for this observed increase. We determine that part of Bering Strait throughflow is driven by the difference in pressure across the strait, or an across‐strait slope in sea surface, which can be caused by a stress applied parallel to the strait. When winds blow to the north, water piles up on the Alaskan side creating a pressure difference that is proportional to the flow. When sea ice is absent, winds act directly on the ocean. When sea ice is present, sea ice applies a stress onto the ocean. We find that as the Arctic loses sea ice, there are no changes in stress due to fewer days of sea ice cover. This suggests that local winds and sea ice are not driving the increase in transport, and that large‐scale changes in the Pacific and Arctic Oceans are driving the increase in transport through Bering Strait. Key Points: Monthly dynamic ocean topography (DOT) supports that some component of flow through Bering Strait is in geostrophic balanceLocal surface stress in Bering Strait increases to the south as the interior flow increases to the north when sea ice is presentThe increasing number of open water days each year is not contributing to enhanced northward transport via increased wind stress input [ABSTRACT FROM AUTHOR] |
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