Satellite observation on upwelling phenomena in northeast Taiwan during Typhoon period:a case study “HAITANG”

• Main Authors: Hsiu-Ting Liao, 廖秀庭
• Other Authors: Ming-An Lee
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/19073346757526551651

碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 94 === Clear skies, subsequent to Typhoon HAITANG passage across Taiwan in July 2005, provided an opportunity to investigate ocean-atmosphere interaction in the northeast waters of Taiwan. The satellite-derived Sea Surface Temperature (SST), chlorophyll concentration a (Chl-a) and Wind data and shipboard measurements have been analyzed during the passing of before and after the typhoon. Before the passage of typhoon the weekly mean of the SST is about 28.84℃, and Chl-a is about 0.36 mg/m3. After the typhoon passes of Taiwan, however, the phenomenon of upwelling is enlarged. The mean SST is decreased to 27.67℃ and lower than before. On the other hand, the Chl-a is higher than before at the average of 0.76 mg/m3. Further, after the 30th July day of typhoon passes, the SST and Chl-a are increase and decrease respectively as well as the condition before the typhoon passes. The present shows that the area of upwelled cold water reached the maximum of 15578 km2, and its mean SST decreases to 26.6℃ in 24 th July. In addition, we estimated the Ekman Pumping Velocity from the QuickSCAT wind filed data. It shows that the velocity is -6.19×10-6 m/s before the passage of typhoon and increased to 21.76×10-6 m/s while the typhoon landed. After the passage, the velocity was decreased to 0.98×10-6m/s violently. Furthermore, the wind direction may change the flow pattern and strength of Kuroshio, and then affected the upwelling of Kuroshio subsurface water. However, the different typhoons make the difference wind filed around the I-Land Ridge. It suggested that the variation of upwelling may related to wind field.