Analysis on the seasonal phenological characteristics of the Heihe River Basin with AVHRR NDVI data set

The Normalized Difference Vegetation Index (NDVI) data set of the Heihe River Basin (96.45/spl deg/-102.8/spl deg/E, 35.4/spl deg/43.5/spl deg/N) from April 1992 to September 1993 and from February 1995 to January 1996 was derived from the NOAA Pathfinder AVHRR data set. The principal component analysis was applied to the data set. The seasonal phenological characteristics of the Heihe River Basin was obtained by analyzing the first four principal components.