農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

本研究處理分析1997-2007年衛星遙測海面水溫、海洋水色及海面高度影像，配合Argos衛星漂流浮標觀測資料，利用單一等值線、驗正交函數及小波分析等方法，探討黑潮暖流時空分布與主流軸指標，及其對鮪旗魚類漁獲分布之影響。研究結果顯示，利用衛星水溫及水色散佈圖分析，選定出代表黑潮左邊界之黑潮左牆的水色濃度指標，春、秋季為0.2 mg/m3，夏季為0.15 mg/m3，冬季為0.4 mg/m3，並發現台灣東部海域黑潮左牆有夏季離岸及冬季近岸現象，夏季離岸約15-45浬，冬季時則貼近台灣東海岸。再者，Argos衛星浮標觀測值，顯示黑潮主流區的表層流速值為75-150 cm/sec，而其時空對應的衛星海面高度值為220-260 cm，選定海面高度值為230及240 cm等值線指標，分別作為冬、夏兩季之黑潮主流軸指標，發現台灣東部及日本南方海域的黑潮主流軸有較大的時空變動，而黑潮主流軸於東海陸棚邊緣則相對穩定，另於台灣東部海域亦呈現夏季離岸及冬季近岸現象。另外，由2003-2007年月別衛星海面高度影像之經驗正交函數分析，得知第一主成分影像可解釋87.4%的總變異，顯示出黑潮暖流海域典型的衛星海面高度值分布型態，即黑潮主流區的海面高度較高，且其主要變動週期為12個月。總之，本研究利用衛星遙測影像觀測黑潮暖流時空動態結果，可提供未來發展黑潮暖流速預報重要基礎。再者，本研究探討黑潮暖流的時空動態對鮪旗魚類漁獲分布之影響，發現1-3月份時，黑潮暖流之衛星海面高度距平值普遍較低，且於日本南方海域出現明顯的冷水塊分布，並以鮪魚類漁獲為主，約佔總漁獲組成高達90%以上，單位努力漁獲量則可達每100鉤捕獲4-5尾。於6-11月份時，黑潮暖流之衛星海面高度距平值明顯較高，此時旗魚類漁獲相對增加，但整體單位努力漁獲量則明顯下降，每100鉤僅捕獲3尾以下。關鍵詞：衛星遙測、地理資訊系統、海面高度、經驗正交函數、鮪旗魚類

The multi-satellite remote sensing data, including sea surface temperature (SST), ocean color (chlorophyll-a concentration, Chl-a), and sea surface height (SSH) during 1997 to 2007 were applied to examine the variability of the Kuroshio current and in relation to the catch per unit effort (CPUE) distribution of tuna-species in this study. The specific contour, empirical orthogonal function (EOF) and wavelet analysis were used, respectively. As a result, the scatter plots of SST and Chl-a data of the Kuroshio could be identified to determine the seasonal Chl-a indicators of the left wall of the Kuroshio current (LWKC). The Chl-a indicator of LWKC is 0.2 mg/m3 in spring and autumn. The Chl-a indicator of LWKC is 0.15 mg/m3 and 0.4 mg/m3 in summer and winter, respectively. Those seasonal Chl-a indicators showed that the Kuroshio usually come close to the east of Taiwan in winter and move toward offshore at a distance of 15-45 nautical miles in summer. Moreover, the current velocities of the Kuroshio mainstream derived from Argos satellite drifters ranged from 75 to 150 cm/sec, corresponding with the SSH data ranged from 220 to 260 cm. Then the specific 230 and 240 cm contours of SSH had been used to be the indicators of the Kuroshio axis during the summer and winter periods. The Kuroshio axes had the significant displacement in the east of Taiwan and south of Japan. But the Kuroshio axis had a relative stable distribution in the east of East China Sea. The Kuroshio axes derived from Argos drifters had also shown the Kuroshio usually come close to the east of Taiwan in winter and move toward offshore in summer. Additionally, the EOF analysis of monthly SSH data during 2003 to 2007 had determined the first EOF mode accounted for 87.4 % of total variance and revealed the interannual and typical highly SSH distribution of the Kuroshio. Finally, the catch distribution of tuna species in relation to the variation of the Kuroshio was examined in this study. The monthly CPUE distributions of tuna species were overlaid to the SSH anomaly images had shown that the higher tuna catch (its average CPUE more than 4-5 fishes/100 hooks) associated with the negative SSH anomaly of the Kuroshio from January to March. But the higher billfish catch (its average CPUE less than 3 fishes/100 hooks) was found to correspond with the positive SSh anomaly.Keywords: Satellite remote sensing, Sea surface height, Geographic information system, Empirical orthogonal function, Tuna species