DOI: 10.1029/2018JC013931
Scopus记录号: 2-s2.0-85050492875
论文题名: Observations of Shelf Exchange and High-Frequency Variability in an Alaskan Fjord
作者: Merrifield S. ; Otero M. ; Terrill E.
刊名: Journal of Geophysical Research: Oceans
ISSN: 21699275
出版年: 2018
卷: 123, 期: 7 起始页码: 4720
结束页码: 4734
语种: 英语
英文摘要: High-frequency observations collected over 3 years are used to describe upper-ocean variability in Behm Canal, a nonglacial fjord in Southeast Alaska. The fjord is sheltered by surrounding topography and connected to the outer continental shelf by a 400-m-deep strait. Summer conditions are characterized by strong near-surface stratification, a sea breeze wind regime, and tidally dominated flows. In nonsummer months, baroclinic subinertial flows exceeding 0.5 m/s dominate the velocity record. The flow events represent a wind-driven response to low-pressure systems that impact the coast as they propagate across the Gulf of Alaska. The observations suggest that the storm systems generate downwelling events that propagate into the fjord with a mode-one-like vertical structure in the upper 60 m. Following the initial up-fjord current pulse lasting approximately a day, a down-fjord flow occurs lasting several days, the duration of the downwelling anomaly. These subinertial downwelling events likely are the dominant mechanism of shelf-fjord exchange, with estimated fjord-flushing times of 50 days. The downwelling events are accompanied by enhanced near-inertial shear, which exhibits downward energy propagation. Evidence for enhanced energy near the maximum buoyancy frequency in the thermocline suggests high-frequency internal wave trapping, with the primary energy source in the semidiurnal band associated with tidal and wind forcing. The observations highlight the importance of shelf-fjord coupling through meteorological forcing and the existence of internal wave energy at a range of frequencies, which have implications for mixing and transport within the fjord. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/113628
Appears in Collections: 气候减缓与适应
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作者单位: Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, CA, United States
Recommended Citation:
Merrifield S.,Otero M.,Terrill E.. Observations of Shelf Exchange and High-Frequency Variability in an Alaskan Fjord[J]. Journal of Geophysical Research: Oceans,2018-01-01,123(7)