青藏高原春夏季对流层温度异常特征

Anomaly Characteristics of Spring and Summer Temperature in Troposphere over Tibetan Plateau

利用NCEP/NCAR再分析资料,在揭示青藏高原对流层中上层（500～200hPa）温度变化特征的基础上,通过比较与同纬度地区对流层中上层温度的差异,从温度纬向偏差角度定义了一个高原热力指数（TDI）,并分析了该指数在春夏季的多时间尺度变化特征。结果表明：1由春到夏,亚洲对流层中上层的暖中心经历了从西太平洋西进到大陆,并逐渐发展控制整个东亚地区,之后东退的过程。春季扰动温度暖中心由我国华南地区逐渐西移至高原南部,中心强度逐渐增大,夏季扰动中心稳定在青藏高原南部;2TDI的年变化曲线呈现出明显的单峰型特征,表明高原的热力作用从4月开始明显增强,并在7月达到最大,9月后又迅速减弱;3各月TDI的最高值、最低值和平均值均表现出夏季大冬季小的特征,夏季TDI变幅明显小于其他季节;4TDI具有明显的年际变化,但春（夏）季该指数存在一定（明显）的月际差异,且无明显的线性变化趋势。

By using the NCEP/NCAR reanalyzed data,the differences of the mid-upper troposphere temperature in the areas of the same latitude are compared,based on the temperature variations in the midupper troposphere over the Tibetan Plateau（500to 200hPa）.TDI（Tibetan middle-high level temperature zonal Deviation Index）is defined by the zonal temperature deviation.Moreover,the characteristics of multiple time scale variations of the index in spring and summer are also presented.Major conclusions are：（1）From spring to summer,the Asia mid-upper troposphere warm center moves westward from the west Pacific to the land and controls the whole East Asia gradually,and then retreats.The disturbance temperature warm center in spring moves westward from the southeast of China to the south of the Tibetan Plateau,and reinforces gradually,but it is stable in Southern Tibetan Plateau in summer.（2）The annual variation curve of TDI shows a single maximum obviously.The thermal effect increases gradually in April and reaches the maximum in July,then decreases rapidly after September.（3）The maximum,minimum and average value of TDI in all months are high in summer and low in winter.TDI in summer changes slightly.（4）The inter-annual change of TDI is obvious,but the index of spring（summer）has certain（obvious）monthly variation and there is no obvious linear trend.