Global analyses of satellite-derived vegetation index related to climatological wetness and warmth

摘要: Wetness and warmth are the principal factors that control global vegetation distribution. This paper investigates climate–vegetation relationships at a scale using normalized difference index (NDVI), (WAI), wetness (WEI). The NDVI was derived from global, 20-year Advanced Very High Resolution Radiometer (AVHRR) dataset with 4-min resolution. The WEI defined as ratio of precipitation to potential evaporation. WAI cumulative monthly mean temperature exceeds 5 °C annually. Meteorological data International Satellite Land-Surface Climatology Project Initiative II (ISLSCP II) were used calculate WAI. All analyses annual values based on averages 1986 1995 1 × degree resolution over land. Relationships among NDVI, WEI, examined vegetation-climate diagram orthogonal coordinates. The shows large correspond areas tropical temperate forests values. Small associated small desert tundra, respectively. Two major regimes revealed by diagram: dominant dominant. dominates mid- low latitudes. Warmth high latitudes north 60°N or elevated land such Tibetan Plateau. boundary between two roughly corresponds taiga forest southern vegetation. Over northern Eurasia, occurs in where is maximum around 18 °C. Copyright © 2006 Royal Society.