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
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.