长江源区水文气象要素变化及其与大尺度环流因子关系研究

长江源区水文气象要素变化及其归因研究一直备受全球关注,现阶段研究多侧重于水文气象要素时空变化特征分析,针对长江源区水文气象要素与大尺度环流因子相互关系的研究不足。论文利用Mann-Kendall法、去趋势波动分析法和小波分析法,探究长江源区1957—2012年水文气象要素趋势性、波动性和周期性变化规律,分析水文气象要素与大尺度环流因子的相关关系,通过研究水汽通量揭示大尺度环流因子对水文气象要素变化的驱动机制。结果表明：20世纪90年代,长江源区气候暖干化,进入21世纪后,长江源区气候暖湿化趋势明显;长江源区水文气象要素序列具有正长程相关性,长江源区气候未来会继续呈现暖湿化变化趋势。长江源区水文气象要素都存在着1~5、10~24和25~45 a三种时间尺度周期变化规律。南亚季风是影响长江源区降水量和流量较为重要的大气环流因子,南亚季风驱动下的西南方向气流是长江源区主导气流和水汽来源。

Changes of Hydro-meteorological Factors and the Relationships with Large-scale Circulation Factors in the Source Region of the Yangtze River

Changes of hydro-meteorological factors in the source region of the Yangtze River are a global concern. Pervious research focused on the temporal and spatial variation characteristics in hydro-meteorological factors. Research on the relationships between hydro-meteorological factors and large-scale circulation in the source region of the Yangtze River is scarce. Based on the hydro-meteorological factors and large-scale atmospheric circulation factors in the source region of the Yangtze River, trends, volatilities and periodic changes of hydro-meteorology factors (precipitation, evapotranspiration and streamflow) during 1957-2012 were explored by using Mann-Kendall method, detrended fluctuation analysis method and wavelet analysis method. The relationships between hydro-meteorological factors and large-scale atmospheric circulation factors were further studied. Meanwhile, the driving mechanism of large-scale atmospheric circulation on hydro-meteorological factors was disclosed by analyzing the water vapor flux in the source region of the Yangtze River. The results showed that climatic situations in the source region of the Yangtze River were basically characterized by warm and dry during 1990s. Since 2000s, the climatic turned to warm and wet. Time series of hydro-meteorological factors in the source region of the Yangtze River had positive long-rang correlations. Climatic situation in the source region of the Yangtze River will keep warm and wet in the future. There were 1-5 year, 10-24 year and 25-45 year periods of hydro-meteorological factors in the source region of the Yangtze River. South Asian monsoon (SAM) is a relative important large-scale atmospheric circulation that can influence the precipitation and streamflow in the source region of the Yangtze River. It is mainly because the southwest vapor fluxes driven by the SAM are dominant source of vapor fluxes in the source region of the Yangtze River.