A study on environmental background of East Asian land cover using digital terrain models
东亚土地覆盖环境背景数字地面模型研究

Based on methods of geographical information system and remote sensing technology, the single element's thematic digital terrain models of the elevation, aspect, slope, temperature, precipitation, maximum potential evapotranspiration, moistureand NDVI, which areintimately related to land cover environmental background in East Asia, are studied under unifiedprojection, unifiedspatial resolution and unifiedcoordination system, respectively. Then all the single elements are integrated to generate synthetic digital terrain models containing characteristics of each element by using Principle Component Analysis method. Finally, the characteristics of environmental background of land cover in East Asia reflected by the synthetic digital terrain model are analyzed. The characteristics of environmental background of land cover in East Asia are as follows: (1)The environmental background of land cover in East Asia has regularities of extention from northeast to southwest and gradation of southeast to northwest. At the same time, the distribution range of this characteristic is consistent with the range of monsoon climate area. We also found the zonal distribution of environmental background in western edge of this region is very complex. These phenomena completely incarnate the complexityof topography and climate in this area. (2)In the monsoon climate area, there exists not only the regularities of longitudinal zonality, characterized by extention from northeast to southwestand gradation from southeast to northwest, but also the regularitiesof latitudinal zonality featured by extention from east to west and gradationfrom north to south. (3)In northwest inland area including Xinjiang, northwestern part of Qinghai-xizang Plateau, western part of Inner Mongolia and southwestern part of Mongolia, a broad sense of eastern part of central Asia dominated by mountainsand basins in topography, the southeast monsoon, temperate westerly and Arctic Ocean air currents are inaccessible to reach this area, so the quality of environmental background of land cover in this area is very low. (4)In northern part of East Asia, because of flat terrain endowed with certain amount of precipitation compared with northwest inland area,the land cover environmental background condition is relatively high and has the longitudinal zonality of extention from east to west and gradationfrom south to north.