Abstract:
In order to study the spatial distribution characteristics of monthly mean NDVI during the past ten years in China, the authors used MODIS MOD/MYD13C2 vegetation spectrum to synthesize monthly NDVI and, combined with China's terrain data, discussed the changing regularity of NDVI with respect to aspect and elevation.The results show that the area ratio of low NDVI value segment -0.25,0.15)is high in winter and low in summer, suggesting the characteristics of bare soil, deserted land and water.The median segment0.15, 0.55 shows the "bimodal double-dip" character, and the area ratio is higher in spring and autumn than in winter and summer, implying features of vegetated mixture land cover.The area ratio of high value segment 0.55, 0.95 is high in summer and low in winter, indicating variation of vegetation cover with seasonal change.NDVI change with aspect shows the "bimodal double-dip" distribution, the NDVI values in southeast and northwest aspects are larger than those in southwest and northeast aspects.With increasing elevation , three NDVI decreasing zones are 250~1 250 m, 2 500~3 000m and 3 750~6 000 m, and two NDVI increasing zones are 1 250~2 500 m and 3 000~3 750 m, respectively.The horizontal and vertical distribution differentiations of NDVI are remarkable, which is attributed to the impact of climate and geographical terrain elements in China.Those regularities may be helpful to the research on land surface process.