DOI: 10.5194/tc-14-3329-2020
论文题名: Frazil ice growth and production during katabatic wind events in the Ross Sea, Antarctica
作者: Thompson L. ; Smith M. ; Thomson J. ; Stammerjohn S. ; Ackley S. ; Loose B.
刊名: Cryosphere
ISSN: 19940416
出版年: 2020
卷: 14, 期: 10 起始页码: 3329
结束页码: 3347
语种: 英语
英文关键词: convection
; dense water
; katabatic flow
; mixed layer
; polynya
; sea ice
; seasonality
; thermal convection
; vertical mixing
; wind velocity
; Antarctica
; East Antarctica
; Ross Sea
; Southern Ocean
; Terra Nova Bay
英文摘要: Katabatic winds in coastal polynyas expose the ocean to extreme heat loss, causing intense sea ice production and dense water formation around Antarctica throughout autumn and winter. The advancing sea ice pack, combined with high winds and low temperatures, has limited surface ocean observations of polynyas in winter, thereby impeding new insights into the evolution of these ice factories through the dark austral months. Here, we describe oceanic observations during multiple katabatic wind events during May 2017 in the Terra Nova Bay and Ross Sea polynyas. Wind speeds regularly exceeded 20 m s-1, air temperatures were below -25 ◦C, and the oceanic mixed layer extended to 600 m. During these events, conductivity–temperature–depth (CTD) profiles revealed bulges of warm, salty water directly beneath the ocean surface and extending downwards tens of meters. These profiles reflect latent heat and salt release during unconsolidated frazil ice production, driven by atmospheric heat loss, a process that has rarely if ever been observed outside the laboratory. A simple salt budget suggests these anomalies reflect in situ frazil ice concentration that ranges from 13 to 266 × 10-3 kg m-3. Contemporaneous estimates of vertical mixing reveal rapid convection in these unstable density profiles and mixing lifetimes from 7 to 12 min. The individual estimates of ice production from the salt budget reveal the intensity of short-term ice production, up to 110 cm d-1 during the windiest events, and a seasonal average of 29 cm d-1. We further found that frazil ice production rates covary with wind speed and with location along the upstream–downstream length of the polynya. These measurements reveal that it is possible to indirectly observe and estimate the process of unconsolidated ice production in polynyas by measuring upper-ocean water column profiles. These vigorous ice production rates suggest frazil ice may be an important component in total polynya ice production. © Author(s) 2020. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164601
Appears in Collections: 气候变化与战略
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作者单位: Department of Science, US Coast Guard Academy, New London, CT, United States; Applied Physics Laboratory, University of Washington, Seattle, WA, United States; Institute for Arctic and Alpine Research, University of Colorado at Boulder, Boulder, CO, United States; Center for Advanced Measurements in Extreme Environments, University of Texas at San Antonio, San Antonio, TX, United States; Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States
Recommended Citation:
Thompson L.,Smith M.,Thomson J.,et al. Frazil ice growth and production during katabatic wind events in the Ross Sea, Antarctica[J]. Cryosphere,2020-01-01,14(10)