青藏高原极端天气气候变化及其环境效应*

青藏高原气候变化敏感性强、幅度大，而极端天气气候变化是高原生态、环境变化的重要驱动因素。过去几十年高原气温增暖幅度明显大于全国平均值，高原绝大部分地区极端高温事件频次显著上升、极端低温事件频次显著下降，并伴随有风速和地表感热加热等气候要素的显著变化。高原极端天气气候事件以及相应的地表和大气热源变化会对高原周边区域天气气候产生重要影响。高原冬春季积雪、春季感热强度以及夏季高原低涡东移发展是东亚夏季风异常和旱涝灾害预报的重要指标，可影响到其下游地区的大气环流和中国东部的天气气候异常。为构建稳固的青藏高原生态屏障，深化对高原极端天气气候环境事件及其对周边区域气候变化影响的研究，建议国家加强高原上对流层—下平流层水汽和微量成分输送过程与机制的研究，加强高原湿地及其对周边区域气候环境变化的影响研究，以及加大投入灾害卫星监测和灾害预警系统的能力建设。

Extreme weather and climate changes and its environmental effects over the Tibetan Plateau

Climate change over the Tibetan Plateau (TP) is characterized by high sensitivity and large amplitude, and the change of extreme weather and climate events are perceived as the principle factor in driving the transformation of environment and ecosystem around the TP. It is noteworthy that the warming amplitude over the TP is obviously larger than the average of China during the last decades. Moreover, the frequency of in situ extreme warm (cold) events presents a significant increasing (decreasing) trend, accompanied by the remarkable alternation of the other climatic elements such as wind speed and surface sensible heat source. Since the thermal forcing of the TP can efficiently modulate the atmospheric circulation and weather and climate to the downstream regions, the snow cover/depth in winter and intensity of the spring sensible heat source over the plateau were regarded as a key index in predicting the anomaly in East Asian summer monsoon and drought and flood disasters in the adjacent regions during the upcoming summer. Thereby it is necessary to explore the atmospheric components transportation processes and mechanism between the upper troposphere and lower stratosphere over and around the TP with coupled models, to pay much more attention to the influence of wet lands, and to build more station observations for evaluating the satellite data inversion, which will deepen the understanding about the extreme weather and climate events over and around the TP and its environmental effects so as to eventually provide scientific basis to the ecological security barrier construction over the TP.