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Satellite Technology for Vegetation Drought Monitoring in Taiwan



本研究收集1991年1月至2002年10月約11年間分佈於全臺之355個雨量站氣象資料,以及1995-2001年間共54幅NOAA衛星影像資料。以地理資訊系統建立雨量資料庫,藉由資料庫的整合針對全臺灣地區的降雨模式進行分析。衛星影像分析方面,則利用於計算臺灣各地區之標準差植生(被)指標(數)(normalized difference vegetation index, NDVI)、植生狀態指標(vegetation condition index, VCI)、溫度狀態指標 (temperature condition index, TCI)及乾旱指標(drought index, DI),並將降雨資料與乾旱指標結合探討其相關性。研究結果顯示,衛星影像於乾旱研究方面可提供不同角度的資訊,有助於對旱災方面的瞭解與防範。

Parallel abstracts

This study collected the climate data recorded by 355 precipitation stations all over the island of Taiwan from January of 1991 to October of 2002 and 54 satellite images of NOAA taken in the period of 1995-2001. The normalized difference vegetation index (NDVI), vegetation condition index (VCI), temperature condition index (TCI), and drought index (DI) were calculated from satellite data. The correlation between precipitation and DI was analyzed. Based on forest type, Taiwan may be divided into 4 regions, i.e., north, center, south, and east. The forest vegetations were recognized as hardwood forest, softwood forest, artificial softwood forest, grass, and mixed forest. The calculated value of NDVI in winter (November-January) was the minimum, whereas that in summer (May-July) was the maximum. Therefore, changes of NDVI may reflect the conditions of drought. There is no difference in DIs among various regions in all seasons, but the northern area showed a slightly higher DI in summer. DIs of central and eastern regions were higher than those of northern and southern regions in autumn. The values of DI calculated from eastern region showed the highest discrepancy between autumn and winter. Results suggest that satellite images of forest vegetation provide information about drought progression status and may be used to establish an early drought forecasting system.