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  • Author or Editor: L. K. Coachman x
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L. K. Coachman
and
R. L. Charnell

Abstract

Salinity-temperature-depth data obtained on several spring and summer cruises during 1976 and 1977 from outer Bristol Bay in the southeast Bering Sea indicate the existence of a zone, between two well-defined water masses, where details of the interaction process are observable. This interaction zone is approximately 100–150 km wide and is characterized by a plethora of mid-water-column finestructure, in both temperature and salinity, that exhibit a hierarchy of vertical scale sizes. Vertical mixing energy within the zone appears low, which results in persistence of interleaving signatures induced by horizontal interaction of the two adjacent water masses. Such interaction probably occurs between all laterally juxtaposed water masses of nearly the same density; outer Bristol Bay allows enhanced examination of the process because of the broad lateral extent of the transition zone.

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T. H. Kinder
and
L. K. Coachman

Abstract

Examination of hydrographic data obtained over a large submarine canyon revealed a cell with a core of high salinity water nestled in the outer (deeper) reaches of the canyon. Bemuse of the T-S distribution within the cell and the current that parallels the continental slope adjacent to the canyon, we suggest that the cell is similar to the current rings which have been observed elsewhere.

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G. M. Voorheis
,
K. Aagaard
, and
L. K. Coachman

Abstract

Dynamic topographies for the region surrounding the tail of the Grand Banks have been examined for the years 1922–65, in an attempt to define the characteristics of the eddies and meanders typical of the circulation pattern. The size distribution of the cyclonic eddies appears to be bimodal and thus suggests the possibility of two different modes of eddy formation. The shear of the mean current system is cyclonic, and it is therefore not surprising that cyclonic eddies dominate over anticyclonic ones by 2.5:1. However, the anticyclonic eddies appear faster; this may in part be associated with the choice of reference level. Other than a seasonal decrease in eddy strength from April-June, no secular trends could be found. The eddies were characteristically found in certain areas only, suggesting that topography plays a role in their formation. The meanders were markedly smaller and slower than those of the Kuroshio front. No secular trends could be found in the meander patterns. A simple vorticity analysis indicates the meander pattern to be bathymetrically controlled.

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David G. Mountain
,
L. K. Coachman
, and
Knut Aagaard

Abstract

Simultaneous current and temperature measurements were made at two depths in Barrow Canyon for a period of 120 days from April through August, 1973. The mean of the measured currents was 25 cm s−1 toward the northeast, such that water moved out of the canyon from the Chukthi Sea toward the Arctic Ocean. The measurements, however, are characterized by higher speeds, commonly in excess of 50 cm s−1, and large variations which resulted in periods of reversed (southwest) up-canyon motion. During these reversed flow periods increased temperatures indicate the presence in the canyon at 126 m depth of Atlantic Water from 200–300 m depth in the Arctic Ocean. A close relationship exists between the measured currents and the north-south atmospheric pressure gradient, such that when the pressure rose to the north, the northward flow of water through the canyon decreased. A simple dynamic model is presented to account for the observed current-pressure relationship.

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T. H. Kinder
,
L. K. Coachman
, and
J. A. Galt

Abstract

The Bering Slope Current flows from southeast to northwest across the Aleutian Basin of the Bering Sea, parallel to the continental slope of the eastern Bering Sea shelf. The water mass characteristics and distributions and the flow field were investigated in August 1972 during T.G. Thompson Cruise 071.

Water mass analysis revealed a southeast-flowing countercurrent bounded by two northwest-flowing bands. The countercurrent was clearly delineated by analyses of a temperature-minimum layer between ∼50–300 m and a temperature-maximum layer between ∼300–800 m. The description of the current as comprised of three bands was supported by parachute drogue measurements and geostrophic calculations along six STD sections normal to the slope.

The dynamic topographies showed an alternative description of the current as a system of eddies, and an interpretation based on incident and reflected planetary waves with a period of one year is presented. The generating mechanism may be related to the strong annual variation in Bering Sea weather.

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