青藏-伊朗高原加热及其对欧-非-印中低纬大气环流的影响和机理

With the deepening of global climate change research, the regional and global climate effects of the heating over the Tibetan Plateau have been paid more and more attention. The researches on the spatial and temporal characteristics of the Tibetan heating and its impact on the weather and climate over East Asia and South Asia have achieved fruitful results. However, little research has been done on the mid-lower latitude Europe-Africa atmospheric circulations on the west of South Asia high. In addition, the high and low level atmospheric circulation configuration over the India Ocean is closely related to both the African atmospheric circulation and the heating over the Tibetan Plateau. Therefore, the proposal will analyze the temporal and spatial characteristics of the atmospheric and surface heating over the Tibetan Plateau and the Iran Plateau and their relation between them, examine the heating influence on Europe-Africa-Indian Ocean atmospheric circulations at the mid-lower latitudes such as the west of South Asia high (intensity and range), the tropical easterly jet, the African monsoon, the transverse circulation over the Indian Ocean, and the intrinsic physical mechanism among them, and study the modulation effect of heating over the Tibetan Plateau and the Iranian Plateau for the relationship between SSTs in the global critical areas and Europe-Africa-Indian Ocean atmospheric circulations and monsoon systems at the mid-lower latitudes, by using the station observation data, satellite data and reanalysis data.

随着全球气候变化研究的深入，青藏高原加热的区域和全球气候效应越来越受到关注。关于青藏高原加热的时空特征，其对东亚、南亚天气气候的影响，已经取得了丰硕的成果；而对南亚高压西侧的欧洲、非洲中低纬大气环流研究甚少。并且南亚高压南侧的印度洋高低层大气环流配置又与非洲大气环流和青藏高原加热都有密切联系。因此，本项目将利用台站观测资料、卫星资料和再分析资料系统分析青藏-伊朗高原表面-大气加热的时空特征和联系；研究其加热对南亚高压西部（强度和范围等），热带东风急流，非洲季风，印度洋上空的transverse环流等欧洲-非洲-印度洋（欧-非-印）中低纬大气环流和季风系统的影响和内在物理机制；并分析青藏-伊朗高原加热对全球关键区海温与欧-非-印中低纬大气环流和季风系统的关系的调制作用。

该项目主要研究了青藏高原未来气候变化的热动力成因、青藏高原加热对西非季风和萨赫尔地区降水的影响、青藏高原加热对东欧-西亚-东亚气候的影响和机理、青藏高原信号对中国东部降水预测水平的提升等。结果表明：1)高原未来整体变暖湿，与气候变暖后Hadley 环流下沉支和中高纬西风环流的极向扩展有关；2) 青藏高原热力异常与同期西非萨赫勒地区降水之间存在显著的正相关关系，两者之间的关系可以用青藏高原至地中海之间的一异常的纬向垂直环流圈和地中海至非洲地区的一异常经向垂直环流圈解释;3) 欧亚大陆对流层温度与青藏高原对流层温度年际尺度上变化是一致的。从欧亚大陆中低纬向其两侧产生了异常热力梯度，因此产生的垂直温度平流和入射短波辐射的增加使得西亚-东欧地区表面气温升高；东亚地区偏强的垂直温度平流和夏季风增强引起的水平温度平流偏强，进而使得长江-黄河流域容易出现高温天气；4) 春季青藏高原对流层温度与华北-河套地区夏季降水量呈显著正相关关系，在海温基础上引入春季青藏高原对流层温度因子后，华北-河套地区夏季降水拟合值与实际降水量的相关系数有明显提高，青藏高原对流层温度预报因子对华北-河套降水的解释方差提高了17.3%。该项目进一步发掘了青藏高原的全球气候效应，将高原的影响拓展到上游的西非、东欧、西亚地区。在机理上，提出青藏高原可以通过改变欧亚大陆中低纬对流层热力结构进而影响欧亚大陆中低纬大气环流，最终影响亚－欧－非气候的新途径和机理；并明确了青藏高原信号的引入对我国东部汛期降水预测能力的定量提升。