关键词: 东亚, 土地覆盖动态, 季风气候, 年际变化, 奇异值分解

Abstract:

The interannual changes of precipitation and land cover in East Asia during May-September have been studied using geographical information system technology based on the time series precipitation data and AVHRR 8 km NDVI data. Simultaneously, the variance regularities of precipitation and land cover in research period have been revealed separately. Furthermore, the paper studied the relationship of interannual changes between land cover and monsoon climate that is represented by changes of precipitation using Singular Value Decomposition (SVD) method. The results are as follows: 1. The precipitation dynamics: (1) The interannual changes of precipitation are apparently divided into three regions, i.e., east monsoon climate region, northwest inland arid region and northern part of East Asia. (2) The interannual changes of precipitation of monsoon region in summer have shown a zonal extension from northeast to southwest, and in that range the precipitation have obvious differences from south to north. (3) The interannual changes of precipitation of northern part of East Asia in summer season present a regularity of east to west zonal distribution, and that zone has character of annual swings of north to south. In the same year, although there exists an east to west change in the same zone, the change range of precipitation is basically unanimous within the whole strip. (4) In the northwest inland arid region except Tianshan and Altay mountains, the precipitation has obvious annual fluctuation in summer, but the range is insignificant in other regions. (5) The positive anomaly percentage of precipitation tends to expand westwards in the late 1980s, i.e., summer precipitation in western China increased gradually in the late 1980s compared with that of the earlier 1980s. 2. The land cover dynamics: (1) Land cover dynamics of summer (May-September) in East Asia are apparently differentiated into three regions such as the northwest inland region, eastern monsoon region and northern part of east Asia. (2) In the monsoon region, land cover dynamics have shown southeast to northwest and south to north differentiations. As regards the whole, the interannual changes of land cover of Northeast China Plain, North China Plain, Southwest China and Huaihe basin are relatively great. (3) In the marginal monsoon area, there exists an obvious dynamic zone expanding from northeast to southwest. This is consistent with eco-environmental fragile area of northern part of China.(4) In the northern part of East Asia, the interannual dynamics of land cover have zonal distribution features. In the same zone, there exist differences from east to west, but the interannual changes are very simple. (5) From the interannual changes of land cover, an increasing trend is seen, especially in the northern part of East Asia and midwest Qinghai-Tibet Plateau except northwest inland arid region. 3. The precipitation and land cover's relations: Based on the SVD models, we have found out that the relation of precipitation dynamics and land cover dynamics are apparently divided into three regions i.e., eastern part of monsoon region, northern part of East Asia and central part of arid region.

Key words: East Asia, land cover dynamic, monsoon climate, interannual changes