The Stratified Characteristics upon Current Fields in Sheng-ao Bay

• Main Authors: Shih-Jie Yang, 楊世傑
• Other Authors: Jian-Hwa Hu
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/47780582028359133188

碩士 === 國立臺灣海洋大學 === 海洋環境資訊學系 === 96 === Among all bays located along the shore of northern Taiwan, Sheng-ao Bay is a small one with a shape most like the letter C. The sea surface water characterized by high temperature and low salinity due to the thermal plume of the power plant and the fresh water of Jioufen Creek stratifies the water column of the bay. It was found in early studies that the current field of the bay was also stratified. Further observations of Sheng-ao Bay’s currents for this thesis include repeated scans of currents from 2m below the surface to the bottom with a shipboard Acoustic Doppler Profiler (ADP), deployments of GPS drifters with drogues near surface and at 6m depth, and repeated casts of CTD survey for vertical hydrographic structure. Comparisons of these observations together with studies of the vertical scattering diagrams of speeds and directions enhance the reliability of the ADP synoptic flow charts and prove the stratification of the current field. Distribution of current directions indicates the variation of clockwise or counterclockwise rotations with depths in flood or ebb tides. In addition, 1.5 knots jet flow could happen at a depth of 4m. Results of experiments in three seasons infer that stratifications of water columns and currents should exist year round. However, Sheng-ao Power Plant stops emitting thermal plumes because of remodeling to expand its capacity in 2008, offering the best opportunity to survey the natural environmental background of Sheng-ao Bay.