THE CONTRIBUTION OF ALASKAN, SIBERIAN, AND CANADIAN COASTAL POLYNYAS TO THE COLD HALOCLINE LAYER OF THE ARCTIC-OCEAN

Citation
Dj. Cavalieri et S. Martin, THE CONTRIBUTION OF ALASKAN, SIBERIAN, AND CANADIAN COASTAL POLYNYAS TO THE COLD HALOCLINE LAYER OF THE ARCTIC-OCEAN, J GEO RES-O, 99(C9), 1994, pp. 18343-18362
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Oceanografhy
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
ISSN journal
2169-9275 → ACNP
Volume
99
Issue
C9
Year of publication
1994
Pages
18343 - 18362
Database
ISI
SICI code
2169-9275(1994)99:C9<18343:TCOASA>2.0.ZU;2-4
Abstract
Numerous Arctic Ocean circulation and geochemical studies suggest that ice growth in polynyas over the Alaskan, Siberian, and Canadian conti nental shelves is a source of cold, saline water which contributes to the maintenance of the Arctic Ocean halocline. The purpose of this stu dy is to estimate for the 1978-1987 winters the contributions of Arcti c coastal polynyas to the cold halocline layer of the Arctic Ocean. Th e study uses a combination of satellite, oceanographic, and weather da ta to calculate the brine fluxes from the polynyas; then an oceanic bo x model is used to calculate their contributions to the cold halocline layer of the Arctic Ocean. This study complements and corrects a prev ious study of dense water production by coastal polynyas in the Barent s, Kara, and Laptev Seas. Recurrent polynyas form on the Canadian and Alaskan coasts from Banks Island to the Bering Strait and on the Siber ian coast from the Bering Strait to the New Siberian Islands. In the B ering Sea, polynyas form in Norton Sound, south and west of St. Lawren ce Island, and in the Gulf of Anadyr. Two regions that account for alm ost 50% of the total dense water production are the Siberian coastal p olynyas in the adjacent regions of the Gulf of Anadyr and Anadyr Strai t and the Alaskan coastal polynyas which occur along the coast from Ca pe Lisburne to Point Barrow. For all of the western Arctic coastal reg ions examined, the mean annual total brine flux is 0.5 +/- 0.2 Sv. Com bination of this flux with the contribution from the Barents, Kara, an d Laptev Seas, which is recalculated from data in the earlier study, s hows that over the entire Arctic, coastal polynyas generate about 0.7- 1.2 Sv of dense water. This compares well with the theoretical estimat es of 1-1.5 Sv. Because an unknown fraction of the Barents, Kara, and Laptev brine flux must go to the Eurasian Basin deep water, the coasta l polynyas alone cannot renew the halocline layer. Other potential bri ne generation mechanisms include overall freezing on the shelves and t he response of the ice to infrequent violent storms. For example, duri ng February 1982 an intense storm generated a large region of low ice concentration in the eastern Chukchi Sea over Barrow Canyon. The refre ezing of the region was followed by the flow of a dense plume down Bar row Canyon. Although the ocean dynamical response to this refreezing n eeds to be established, the possible response of a Barrow Canyon flow to this refreezing event suggests that the overall refreezing in respo nse to infrequent violent storms may be a potential source of the addi tional brine needed to maintain the Arctic Ocean halocline.