In the last decade the lowered Acoustic Doppler Current Profiler
(LADCP) has become an important instrument in measuring
full-water-depth profile of velocity in the open ocean. The basic principle
of the LADCP is to lower one or two self-contained ADCP, one looking
downward and the other looking upward, together with the CTD rosette
during the hydrographic cast. After careful analysis of the ADCP data it is
possible to retrieve surface ¡Vto-bottom profile of horizontal current
velocity. In the present study we have conducted three cruises (21-25
April, 7-10 July and 11-13 October of 2007) in the Lanyu area to survey
the Kuroshio flow structure by using the first set of LADCP in Taiwan. A
total of 34 LADCP/CTD casts were completed. The results indicate that a
major branch of the Kuroshio is located at the region between Taiwan and
Lanyu, with a seasonal variation of flow intensity and vertical extent.
Surface currents can reach a maximum speed of 70-140 cm/s northward.
Kuroshio has a strongest speed (~140 cm/s) in October followed by July
(~100 cm/s) and April (~90 cm/s). The vertical extent of the Kuroshio can
extend to 400-m depth in October, 600-m depth in July and 400-m depth
in April. A southward reverse current can be observed off the southeast
Taiwan coast in depths between 200 and 800 m and the speed ranges
between 30 and 60 cm/s. This southward flow is strongest in April (~60
cm/s), followed by July (~40 cm/s) and October (~30 cm/s). A cyclonic,
cold eddy was observed in the eastern side of Lanyu from the shipboard
ADCP data during the April cruise. The Kuroshio flows to the northwest
during ebbs and to the northeast during floods from the LADCP observations at different tidal phases in July. Finally, analysis of the
temperature-salinity characteristics of the CTD data reveals that the South
China Sea waters can penetrate into and mix with the Kuroshio waters
more significantly in summertime than in other season.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0213108-173407 |
| Date | 13 February 2008 |
| Creators | Yang, Cai-Ming |
| Contributors | Chung-Pan Lee, Ruo-Shan Tseng, Guan-Yu Chen, Y.-J. Yang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0213108-173407 |
| Rights | unrestricted, Copyright information available at source archive |
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