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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/29961

Title: 東海海表面特徵之衛星觀測
Satellite Observation of Sea Surface Features in the East China Sea
Authors: Syu-Jie Yang
Contributors: NTOU:Department of Marine Environmental Informatics
Keywords: 東海;MODIS;經驗正交函數;ONI指標;剪力波;最大符合相似圖形法
East China Sea;MODIS;Empirical Orthogonal Function;Oceanic Niño Index;shear wave;Maximum Similarity Shape Matching
Date: 2011
Issue Date: 2011-11-25T03:30:25Z
Abstract: 本研究利用中解析度影像光譜儀 (Moderate Resolution Imaging Spectroradiometer, MODIS)海表溫月平均資料以及熱紅外波段 (第20波段)即時影像分別探討不同時間尺度下東海海表面特徵變化。藉由長期月平均(考慮期間2002年7月至2010年12月)可以看出東海海表溫主要由西北往東南遞增,且在台灣東北部及杭洲灣外各有一明顯低溫區。海洋聖嬰指標 (Oceanic Niño Index, ONI)顯示本研究時間內共有四起聖嬰及兩起反聖嬰事件,而經由經驗正交函數 (Empirical Orthogonal Function, EOF)分析發現在聖嬰期間冬季海表溫較鄰近年份高,夏季則不明顯。經由去除時間平均之EOF分析可看出西北大陸沿岸一帶海表溫隨時間變化較東南外海一帶大。由熱紅外波段即時影像可看出在長江出海口及黑潮外側之冷暖水交會處會形成鋒面,且鋒面不穩定時會產生平躺於海表面之剪力波 (shear wave)。藉由最大符合相似圖形法 (Maximum Similarity Shape Matching, MSSM)可以推算剪力波之波速。研究發現近岸地區之剪力波波速較外海略高,推論可能是近岸地區除了受大氣之影響外,還有出海口排水的影響。
In this study, the Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) monthly data and real-time thermal infrared (band 20) images are used to discuss the sea surface feature of different time scale in the East China Sea (ECS). By using the long-term monthly mean images (during the period from July 2002 to December 2010) we can see that the SST in the ECS increases spatially from northwest to southeast. Meanwhile, two clear cold areas off the northeast Taiwan and outside the Hangzhou Bay. According to Oceanic Niño Index (ONI), it is found that there are 4 El Niño and 2 La Niña events from 2002 to 2010. The Empirical Orthogonal Function (EOF) shows that the SST was always high In El Niño years, no clear SST variation during El Niño summers. The temporal de-mean EOF analysis shows that the SST variation of the northwest in-shore area is higher but lower in the off-shore area. From real-time thermal infrared images, it is found that a front happens in the boundary between Yangtze River estuary and outside of the Kuroshio, and the unstable front will form a shear wave train. The Maximum Similarity Shape Matching (MSSM) can compute its translational velocity from two consecutive images. It is found that the velocity of shear wave in the coastal regions is higher than off-shore area. Besides the atmospheric effect to cause shear wave, the extra influence of estuary draining may cause the in-shore shear wave moving faster.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M98810011
Appears in Collections:[海洋環境資訊系] 博碩士論文

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