Current dynamics Vertical movement of water masses in the western part of the Sea of
Recent observations of the well studied dichothermal layer (with T < 0 °C) in the Sea of Okhotsk provides an update of its inner structure. In the 1990s, CTD vertical soundings with 1 m resolution found cases of “double ” or “triple ” dichothermal layers on the continental slope and in the deepes...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.360.1797 http://www.pices.int/publications/scientific_reports/Report36/107-112-Vertical-movement.pdf |
| Summary: | Recent observations of the well studied dichothermal layer (with T < 0 °C) in the Sea of Okhotsk provides an update of its inner structure. In the 1990s, CTD vertical soundings with 1 m resolution found cases of “double ” or “triple ” dichothermal layers on the continental slope and in the deepest part of the Sea of Okhotsk. The genesis of those phenomena is linked with pre-winter cooling of the water column, following convection and brine rejection under ice floes, and frontal interactions between water masses. Based on new data to explain dichothermal structure, we note an obvious discrepancy between calculated winter convection depth and real descending horizons for subzero temperatures reaching few hundreds meters at the southwestern part of the Sea of Okhotsk. Because of the lack of applied theory to account for vertical movements in the Sea of Okhotsk, an experiment using year-round mooring data was conducted for its study. From August 2006 to October 2007, the N-5 mooring was deployed at the northern tip of Sakhalin Island in the western part of the Sea of Okhotsk at mid-shelf depth around 100 m close to the region where the East Sakhalin Current originates. A year’s run of vertical current data showed clear seasonal signals averaged over the whole depth layer current changing from downwelling in the summer to the upwelling during cold period of the year. The vertical structure showed a complex nature with heterogeneous vertical movements occurring at relatively shallow depths on the Sakhalin shelf. Differences in vertical current structure are discussed for the fall, winter, spring, and summer seasons alternately with vertical movements through the year. |
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