【摘要】 依据1971-2010年地面观测气象数据,计算了三江源地区湿润指数。利用经验正交函数分解(EOF)和偏相关系数,对近40 a三江源地区干湿状况变化的时空特征及其影响因素进行了分析。结果表明:三江源地区干湿状况的变化在其北部与南部、东部与西部间存在明显反相位变化特征。北部和东部的部分区域分别在20世纪90年代和21世纪后表现出气候湿润化趋势,其余大部地区的持续干旱化趋势始于20世纪80年代初,其中南部与西部变干趋势显著,其湿润指数线性趋势率达到-8%/10 a。虽然三江源地区干湿状况主要决定于降水量和相对湿度的变化,但20世纪90年代中期后气温的显著上升,使得气温也成为关键的影响因子之一,即使在降水明显增加的背景下,也引起三江源主体区域湿润指数的明显下降。气候变暖情景下,北部和东部地区在近十几年暖湿化趋势明显,其余大部地区表现为不同程度的暖干化趋势。更多还原

【Abstract】 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.更多还原