利用NOAA AVHRR植被指数数据集分析黑河流域季候特征

Analysis on the Seasonal Phenological Characteristics of the Heihe River Basin with AVHRR NDVI Data Set

利用 NOAA AVHRR的全球归一化植被指数（NDVI）的高时间分辨率数据集，建立了黑河流域 1992-1993和1995-1996两个年度的NDVI数据，范围在96．45°～102．8 °E，35．4°～43．5°N之间。对此数据进行主成分分析（PCA）．提取了前4个主成分分量，分析了黑河流域季候变化特征。结果表明，第一主成分展示了黑河流域NDVI值在分析时段内的综合空间分布结构、累积状况以及地域差异；第二主成分反映黑河流域的NDVI变化不但具有明显的年周期，而且表现出强烈的季节性，是冬夏分明的季节因素所导致；第三主成分主要指征了平原人工绿洲区显著的农作物生长期；第四主成分反映出山区自然植被与平原人工绿洲植被具有明显不同的生长期和物候特征，该成分可以被用于区分不同的地表覆盖类型。

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) wasapplied to the data set. The seasonal phonological characteristics of the Heihe River Basin were obtained byanalyzing the first four principal components. The results showed that the first principal component indi-cates the spatial pattern of the cumulative NDVI value in the Heihe River Basin, which varies greatly withdifferent geomorphological units. The second principal component reflects that the phenological variationof NDVI in this region has obvious annual-cycle and significant seasonal variability. The third principalcomponent mainly manifests the distinct growing-season of the artificial oasis. The fourth principal compo-nent reflects the seasonal variations of NDVI caused by different vegetation types. There are significantdifference in growing period and vegetation phenological characteristics between natural vegetation in themountainous area and artificial vegetation in the plain-oasis. Obviously, the fourth component can be usedto classify different types of land covers.