全球变暖背景下东亚夏季风TBO的年代际变化特征及其机理分析

The droughts and floods caused by the East Asian summer monsoon (EASM) account for a large proportion of the climate disaster, causing severe economic loss. Therefore, the EASM interannual /interdecadal variability has been a hot and difficult problem in Chinese climate research. When it comes to the prediction of the East Asian summer monsoon (EASM), Chinese Scientists have been paying a great effort on it. Tropospheric quasi-biennial oscillation (TBO) of the EASM provides a prospective scientific point for the prediction of EASM. Recently, the global warming is still going on and the related climate change is brought to the forefront. Previous studies found that the EASM’s TBO shows an obvious interdecadal change during the significant global warming. However, it is still unknown about how the EASM’s TBO interdedacal change happens and what the physical mechanism is. Considering these factors, this project plans to investigate the interdecadal change of the EASM’s TBO during the significant global warming period, and furthermore reveals the physical mechanisms through the statistical methods and numerical experiments. This study is in favor of understanding the roles of global warming in the climate change around China. At the same time, this project would make a great effort to improve the prediction of the EASM, and would further favor to reduce the natural disasters and economic loss.

由东亚夏季风异常所带来的旱涝灾害在气候灾害中占很大比重，给国民经济带来了严重的损失，因此东亚夏季风年际及年代际变率一直是我国气候研究领域的热点和难点问题。东亚夏季风准两年周期振荡（TBO）规律的发现为我国气候预测提供了有力科学依据。然而，近年来的研究表明随着全球变暖的加剧东亚夏季风TBO出现了显著的年代际变化特征。目前对东亚夏季风TBO这种变化特征的认识有待进一步深入，尤其是对控制TBO年代际变化的物理因子尚不清楚。基于以上考虑，本项目拟利用观测资料和再分析资料，全面分析20世纪70年代后期东亚夏季风TBO的年代际变化特征，并通过统计－动力和数值模拟等方法揭示产生TBO年代变化的物理机制。本项目的开展不仅有利于深入认识全球变暖在中国气候变化中的作用，同时对提高我国气候预测水平、减轻气候灾害所造成的损失有重要的意义。

目前我们对东亚夏季风变异的预测能力比较有限，这反应了东亚夏季风的复杂性，因此深入认识东亚夏季风准两年振荡（TBO）的规律可以为东亚夏季风预测提供有力的科学依据。本项目揭示了东亚夏季风TBO的年代际变化特征。1979年以前东亚夏季风TBO振幅强度较弱，1979年以后振幅显著增强。在风场上表现为低层西北太平洋异常气旋和反气旋环流转换在1979年以后显著增强。在夏季降水场上1979年以前显著的TBO信号出现在华南地区，而在1979年以后夏季降水显著的TBO信号出现在中国中部地区。本项目进一步揭示了东部型和中部型ENSO事件的年代际转变在TBO年代际变化中的作用，另外本项目研究表明印度洋和大西洋在1979年以后的增暖对东亚夏季风TBO的年代际变化有重要的影响。此外，本项目揭示了热带太平洋和热带北大西洋海温异常对TBO关键环流系统（即西北太平洋异常反气旋）影响的差异及其机理。本项目的研究对深入认识东亚夏季风变异，提高东亚夏季风气候预测有重要的意义。本项目共计发表文章6篇（其中SCI文章5篇）。