Drifter Observations of Anticyclonic Eddies near Bussol' Strait, the Kuril Islands |
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Authors: | Alexander B Rabinovich Richard E Thomson Steven J Bograd |
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Institution: | (1) Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, B.C., V8L 4B2, Canada;(2) P.P. Shirshov Institute of Oceanology, Moscow, 117851, Russia;(3) NOAA/NMFS Pacific Fisheries Environmental Laboratory, Pacific Grove, CA, 93950-2097, U.S.A |
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Abstract: | Hydrographic surveys and satellite imaging reveal that mesoscale anticyclonic (AC) eddies are common features of the area
south of Bussol' Strait, the deepest of the Kuril straits connecting the western North Pacific and Sea of Okhotsk. To examine
the velocity structure of these eddies, we deployed groups of 15-m drogued satellite-tracked surface drifters over the Kuril-Kamchatka
Trench in the fall of 1990 and late summer of 1993. Drifters in both groups entered large AC eddies centered over the axis
of the trench seaward of Bussol' Strait and subsequently underwent a slow northeastward translation. One drifter (Drifter
1315) deployed near the center of the “Bussol' eddy” in 1990, remained in the eddy for roughly 45 days and made five loops
at successively greater distances from the eddy center. Large-amplitude (80–100 cm/s) storm-generated inertial oscillations
were observed during the first two loops. The vorticity field associated with the eddy resulted in a Doppler “red-shift” of
inertial frequency motions such that the “effective” inertial period of 21 hours was roughly 4 hours greater than the nominal
inertial period for the drifter latitude (45°N). In 1993, a second drifter (Drifter 15371) was retained in the Bussol' eddy
for about 40 days. This eddy had characteristics similar to those of the 1990 eddy but was devoid of significant high-frequency
motions until the drifter's final half loop. The observed spatial scales, persistence, and slow poleward translation of the
eddies suggests that they play an important role in the dynamics of the East Kamchatka and Oyashio current systems.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | Kuril-Kamchatka Trench Bussol' Strait inertial currents satellite drifters |
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