1971 － 2010 年三江源地区干湿状况变化的空间特征

The Three-River Source Region ( TRSR) ，the source region of Yangtze River，Yellow River and Mekong River，is located in the hinterland of the Qinghai － Tibetan Plateau． With a typical continental plateau climate and alpine vegetation ecosystem，the water and heat matching is a key to vegetation variation over region． In this study， monthly humidity indexes in TRSR were computed using ground-observed monthly air temperature，precipitation， wind speed，relative humidity and air pressure from 1971 － 2010，based on the method of Ecological and Meteorological Monitoring Standard which recommended by China Meteorological Bureau． The spatio-temporal variation of aridity /humidity conditions and its dominated factor were analyzed using the method of Empirical Orthogonal Function ( EOF) ，linear correlation and partial correlation analysis． The results show a clear of opposite mode in the zone of northern toward southern and western toward eastern in TRSR． It was found that there is a wet tendency after 1990s and 21st century in the zone of northern and eastern respectively，but a continual dry tendency since 1980s，especially in the zone of southern and western with a remarkable decreased trend( － 8% /10a) ，occurred in other area of TRSR． Aridity /humidity conditions are controlled by precipitation and relative humidity in generally， but the situation is changed evidently after Mid-1990s in the most area of TRSR due to a significant warming，and temperature plays a key of factor to dominate a decreased trend of humidity index even if precipitation increases markedly since then． Under a scenarios of climate warming，it shows a tendency of heat and wet obviously in the zone of northern and eastern and heat and aridity in a certain extent in most area of TRSR．