Relationships between meridional profiles of satellite-derived vegetation index (NDVI) and climate over Siberia

This study investigates the regional relationship between the satellite-derived vegetation index (Normalized Difference Vegetation Index, NDVI) and climatological parameters (temperature and precipitation) over Siberia on a 5-year (1986-1990) annual mean basis. The NDVL in Siberia shows a large value around the 60 degrees N zone, and it gradually decreases toward the southern arid region and the low temperature polar region. This meridional profile (south-north regionality) of the NDVI was analysed in two meridional transects, along 75 degrees E (arid-forest transect) and 110 degrees E (forest-tundra transect). A modified warmth index (WI(0)) was utilized as a temperature index. In the 75 degrees E transect, high positive (0.79) and negative (- 0.58) correlations were found in the NDVI-precipitation and the NDVI-WI(0), meridional profiles, respectively. This fact implies that precipitation plays a role in providing water and dominates the vegetation distribution, while high temperature induces dryness and water shortages, i.e. the critical factor for the vegetation meridional profile is available water in the arid-forest transect. In the 110 degrees E transect, a high positive (0.92) correlation was found, which suggests that the dominant factor for the NDVI profile is temperature in the forest-tundra transect, i.e. the critical factor for the vegetation meridional profile here may be temperature. Furthermore, these meridional profiles were scrutinized in terms of the station altitude and it was suggested that the NDVI tends to change depending on the WI(0) and precipitation at regional variations, which are basically the result of the altitude difference between the stations. The comprehensive relationship between the NDVI, WI(0) and precipitation regionalities is discussed in terms of six vegetation types. The result shows that high NDVI (> 0.2) is observed when the WI(0), is over 40 degrees C and precipitation is more than 2.5 x WI(0) + 50. Copyright (C) 2000 Royal Meteorological Society.