关键词: 归一化植被指数, 主成分分析, 黑河流域, 季候特征

Abstract: The Normalized Difference Vegetation index (NDVI) data set of the Heihe River Basin (96. 45°~102. 8°E,35. 4°~43. 5°N) from April 1992 to September 1993 and from February 1995 to January 1996was derived from the NOAA Pathfinder AVHRR data set. The principal component analysis (PCA) was applied to the data set. The seasonal phonological characteristics of the Heihe River Basin were obtained by analyzing the first four principal components. The results showed that the first principal component indicates the spatial pattern of the cumulative NDVI value in the Heihe River Basin, which varies greatly with different geomorphological units. The second principal component reflects that the phenological variation of NDVI in this region has obvious annual-cycle and significant seasonal variability. The third principal component mainly manifests the distinct growing-season of the artificial oasis. The fourth principal component reflects the seasonal variations of NDVI caused by different vegetation types. There are significant difference in growing period and vegetation phenological characteristics between natural vegetation in the mountainous area and artificial vegetation in the plain-oasis. Obviously, the fourth component can be used to classify different types of land covers.

Key words: normalized difference vegetation index (NDVI), Principal Component Analysis (PCA), HeiheRiver basin, seasonal phenological characteristic