Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea
Chlorofluorocarbon (CFC)-12 and -11 (CF2Cl2 and CFCl3) measurements were made in seawater on the Ross Sea continental shelf and adjacent slope region in 1984. Concentrations of CFC-12 and CFC-11 in Ross Sea continental shelf water averaged nearly half that of saturated surface water. Circumpolar Dee...
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ftcdlib:qt3pd07742 2023-05-15T16:41:54+02:00 Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea Trumbore, SE Jacobs, SS Smethie, WM 845 - 870 1991-01-01 application/pdf http://www.escholarship.org/uc/item/3pd07742 english eng eScholarship, University of California qt3pd07742 http://www.escholarship.org/uc/item/3pd07742 Attribution (CC BY): http://creativecommons.org/licenses/by/3.0/ CC-BY Trumbore, SE; Jacobs, SS; & Smethie, WM. (1991). Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea. Deep Sea Research Part A, Oceanographic Research Papers, 38(7), 845 - 870. doi:10.1016/0198-0149(91)90022-8. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/3pd07742 article 1991 ftcdlib https://doi.org/10.1016/0198-0149(91)90022-8 2018-07-13T22:51:24Z Chlorofluorocarbon (CFC)-12 and -11 (CF2Cl2 and CFCl3) measurements were made in seawater on the Ross Sea continental shelf and adjacent slope region in 1984. Concentrations of CFC-12 and CFC-11 in Ross Sea continental shelf water averaged nearly half that of saturated surface water. Circumpolar Deep Water within 50 km of the Ross Sea continental shelf also contained measureable CFC-12 and CFC-11, but an order of magnitude less than shelf waters. CFC-12 and CFC-11 concentrations in the deep water overlying the continental slope increased with depth, indicating recent ventilation and bottom water formation near the continental shelf. Several water masses on the continental shelf that are commonly distinguished on the basis of temperature and salinity characteristics also varied in CFC content, and thus in their modes and rates of ventilation and renewal. A time-dependent model reproducing the 1984 sub-surface shelf water CFC concentrations demonstrates the relative importance of mixed layer entrainment, gas exchange through leads in the winter sea ice field, and mixing with source waters derived from the Circumpolar Deep Water. Model results show that mixed layer entrainment at the beginning of winter is the dominant process ventilating sub-surface shelf water in the eastern Ross Sea, while western shelf waters also require significant gas exchange during winter. Shelf water residence time can only be constrained by the model and available data to 10 years, but most probable values are ∼2.5 years in the eastern Ross Sea and ∼4 years in the western Ross Sea. CFC concentrations in water which has circulated beneath and has been modified by the Ross Ice Shelf indicate that the transformation time from High Salinity Shelf Water to Ice Shelf Water can be as short as 3.5 years. With reasonable oxygen consumption and nutrient regeneration rates, the balance of ventilation and mixing processes that reproduced observed shelf water CFC-12 concentrations also can account for observed oxygen and nitrate levels, if the western surface waters are undersaturated by ∼10% at entrainment. © 1991. Article in Journal/Newspaper Ice Shelf Ross Ice Shelf Ross Sea Sea ice University of California: eScholarship Ross Ice Shelf Ross Sea Western Shelf ENVELOPE(164.448,164.448,-77.780,-77.780) Deep Sea Research Part A. Oceanographic Research Papers 38 7 845 870 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
description |
Chlorofluorocarbon (CFC)-12 and -11 (CF2Cl2 and CFCl3) measurements were made in seawater on the Ross Sea continental shelf and adjacent slope region in 1984. Concentrations of CFC-12 and CFC-11 in Ross Sea continental shelf water averaged nearly half that of saturated surface water. Circumpolar Deep Water within 50 km of the Ross Sea continental shelf also contained measureable CFC-12 and CFC-11, but an order of magnitude less than shelf waters. CFC-12 and CFC-11 concentrations in the deep water overlying the continental slope increased with depth, indicating recent ventilation and bottom water formation near the continental shelf. Several water masses on the continental shelf that are commonly distinguished on the basis of temperature and salinity characteristics also varied in CFC content, and thus in their modes and rates of ventilation and renewal. A time-dependent model reproducing the 1984 sub-surface shelf water CFC concentrations demonstrates the relative importance of mixed layer entrainment, gas exchange through leads in the winter sea ice field, and mixing with source waters derived from the Circumpolar Deep Water. Model results show that mixed layer entrainment at the beginning of winter is the dominant process ventilating sub-surface shelf water in the eastern Ross Sea, while western shelf waters also require significant gas exchange during winter. Shelf water residence time can only be constrained by the model and available data to 10 years, but most probable values are ∼2.5 years in the eastern Ross Sea and ∼4 years in the western Ross Sea. CFC concentrations in water which has circulated beneath and has been modified by the Ross Ice Shelf indicate that the transformation time from High Salinity Shelf Water to Ice Shelf Water can be as short as 3.5 years. With reasonable oxygen consumption and nutrient regeneration rates, the balance of ventilation and mixing processes that reproduced observed shelf water CFC-12 concentrations also can account for observed oxygen and nitrate levels, if the western surface waters are undersaturated by ∼10% at entrainment. © 1991. |
format |
Article in Journal/Newspaper |
author |
Trumbore, SE Jacobs, SS Smethie, WM |
spellingShingle |
Trumbore, SE Jacobs, SS Smethie, WM Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
author_facet |
Trumbore, SE Jacobs, SS Smethie, WM |
author_sort |
Trumbore, SE |
title |
Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
title_short |
Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
title_full |
Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
title_fullStr |
Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
title_full_unstemmed |
Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea |
title_sort |
chlorofluorocarbon evidence for rapid ventilation of the ross sea |
publisher |
eScholarship, University of California |
publishDate |
1991 |
url |
http://www.escholarship.org/uc/item/3pd07742 |
op_coverage |
845 - 870 |
long_lat |
ENVELOPE(164.448,164.448,-77.780,-77.780) |
geographic |
Ross Ice Shelf Ross Sea Western Shelf |
geographic_facet |
Ross Ice Shelf Ross Sea Western Shelf |
genre |
Ice Shelf Ross Ice Shelf Ross Sea Sea ice |
genre_facet |
Ice Shelf Ross Ice Shelf Ross Sea Sea ice |
op_source |
Trumbore, SE; Jacobs, SS; & Smethie, WM. (1991). Chlorofluorocarbon evidence for rapid ventilation of the Ross Sea. Deep Sea Research Part A, Oceanographic Research Papers, 38(7), 845 - 870. doi:10.1016/0198-0149(91)90022-8. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/3pd07742 |
op_relation |
qt3pd07742 http://www.escholarship.org/uc/item/3pd07742 |
op_rights |
Attribution (CC BY): http://creativecommons.org/licenses/by/3.0/ |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/0198-0149(91)90022-8 |
container_title |
Deep Sea Research Part A. Oceanographic Research Papers |
container_volume |
38 |
container_issue |
7 |
container_start_page |
845 |
op_container_end_page |
870 |
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1766032368182755328 |