Spatial variation of water/thermal elements and NDVI with altitudes in central and eastern Tibetan Plateau
青藏高原中东部水热条件与NDVI的空间分布格局

Under joint effect of atmospheric circulation and topography,the distribution of water/thermal elements and vegetation bears a three-dimensional zonal characteristic in Tibetan Plateau.As we know,within the vast expanse of the Tibetan Plateau with undulating terrain,the spatial distribution of water/thermal elements and vegetation has strong local impressions,which are different in one location from the other.This paper aims to explore such a spatial pattern in central and eastern Tibetan Plateau,with ground collected data of air temperature and precipitation from 100 meteorological stations and remotely sensed NDVI data by NOAA AVHRR during 1982-2000.Firstly,latitudinal and longitudinal transects are designed to analyze the role of altitude in spatial distribution of water/thermal elements.Secondly,to focus on roles of latitude and longitude in the above-mentioned spatial pattern,these 100 stations are divided into 5 groups with altitudes restricted nearly within a range of 500 m so as to restrain the influence of altitude. The study shows that 1) because of sharp altitudinal variation,the thermal element in the central and eastern Tibetan Plateau firstly follows the adiabatic lapse rate of air temperature while solar radiation variation over latitudes is the second thermal control factor;2) the spatial distribution pattern of precipitation is relatively complex,which is dominated by the distance to and the accessibility of vapor sources;and 3)finally the annual mean NDVI,the indicator of general vegetation condition,is governed jointly by precipitation and accumulated air temperature,so its spatial variation is the combination of those of the two climate elements.