【作者】 钟珊珊；

【导师】 何金海； 管兆勇；

【作者基本信息】 南京信息工程大学 ， 气象学， 2011， 博士

【摘要】 本文利用NCEPI、ECMWF (ERA)逐日再分析资料计算了大气视热源,采用近年来有关高原实验的实测资料,特别是垂直探空资料以及卫星遥感资料对高原视热源加热率垂直廓线的合理性进行了客观的检验和判断。在此基础上,探讨了青藏高原大气热量源汇的水平、垂直结构特征,揭示了其对我国天气气候的影响。主要结论如下：(1)在3公里以上的高原大部分地区以干对流为主,最大加热高度位于对流层中层的近地面,感热加热的贡献大于潜热加热。在最大加热层上,亚洲季风区强度最大范围最广的加热率中心位于青藏高原上空,而以潜热为主的整层积分的最大加热中心位于孟加拉湾地区北部至高原南侧上空。(2)在高原范围,采用ERA和NCEP/NCAR计算的加热廓线的垂直分布基本合理,ERA计算的结果较NCEP的更接近观测事实。月平均最大加热率高度基本位于500-600hPa之间,但逐日加热廓线却显示高原大气不仅存在低层加热还存在较高层加热。(3)高原热源/汇的变率及热源高度季节进程的最强信号都表现为1990前后的气候突变。突变前,高原大气热源高度偏高,冷源向热源的转换时间早,持续时间长,则纬向海陆热力差异强度在春季偏强而夏季偏弱,江南降水春季偏早偏多,而夏季偏少。突变后,情况相反。高原整层大气热源<Q1>的年际变率最强异常值出现在高原中部偏南和高原的东南部。(4)数值试验表明,通过升高春季西太平洋副热带地区海表面温度可引起同期东亚—西太平洋副热带纬向海陆热力差异减弱,进而引起3-4月中国大陆东部20°-30°N范围内的850 hPa西南风强度减弱,与之相应的3-4月发生在30°N以南地区的降水量明显减少。在此过程中,青藏高原东南侧的低涡强度减弱,该低涡与西太平洋副热带高压之间的位势梯度减小,中低纬度西太平洋副热带高压强度减弱,其北侧的西南风强度相应减弱,因此西南暖湿气流输送也随之减弱,造成江南地区的水汽通量辐合强度明显减弱,这种环流分布状况将不利于出现较强的江南春雨,导致江南春雨强度明显减小。更多还原

【Abstract】 The paper used NCEP I and ECMWF (ERA) reanalysis data, calculated atmospheric apparent heat source by inverse algorithm, and established data set of daily heat source for many years and verified its reasonableness. The paper especially verified and made objective judgment of vertical profile of heating rate over the plateau according to observed data of plateau tests. On these bases, we investigate the horizontal and vertical structure of Qinghai-Tibetan Plateau heating, and reveal its impacts on weather and climate in China. The major work and conclusions are as follows:1) At the maximum heat source layer, the heating rate center with the most intensity and widest extension in East Asia lies in Qinghai-Tibetan Plateau. While the total integration of the biggest heat center focusing on latent heat lies in the region from northern area in the Bay of Bengal to south plateau.2) As far as the heating vertical profiles over plateau are concerned, the results of ERA and NCEP appear reasonable. In contrast, the former is more closed to the observational facts. The monthly mean maximum heating rate height occurs dominantly between 500-600 hPa, but the daily heating profile shows that there is not merely the lower layer heating, and the upper layer heating as well.3) The strongest signals about the variability of the heat source/sink and the seasonal march heat source height are the abrupt climate change around 1990. The strongest centers of interannual variability of<Q1> over Qinghai-Tibetan Plateau appear on the south central and southeast plateau.4) Numerical test indicate that, when the thermal difference between the East Asia and the western Pacific in spring is minished, the intensity of precipitation over the region to south of 30°N will decrease during the period from March to April.更多还原