1990s末"丝绸之路"遥相关型的年代际变化及其对东亚夏季降水的影响

The Silk Road teleconnection pattern (SRT) is one of the notable teleconnection patterns over Eurasian continent during boreal summer, which represents the dominant mode of the interannual variability of the mid-high level atmospheric circulation over extratropical Eurasia. The changes of the location and intensity of the SRT centers reveal large influence on the interannual variability of Eastern Asian summer rainfall(EASR). Our preliminary work indicates an obvious interdecadal change in the location and intensity of the SRT, which brings great impact to the EASR. However, few attentions are paid to this interdecadal change. Therefore, by through observational analysis and numerical study, the present proposal aims to give a further investigation on the interdecadal changes of the SRT, which includes changes in the features and its influence on the EASR, and the possible causes and associated mechanism. In paticular, the present work will discuss the roles of changes in the mean state of the circulation, the global rainfall and sea sea temperature in the interdecadal change of SRT around the late-1990s, and reveal the internal and forced causes related to the interdecadal change. Consequently, this work will favor for a better understanding to the variability and climatic impact of the SRT and provide new evidence for improving the prediction of the Eastern Asian summer climate.

“丝绸之路”遥相关型（SRT）是北半球夏季欧亚大陆上空显著的大气遥相关型之一，它是表征热带外欧亚大陆地区中上层大气环流年际异常的主要模态，其中心位置和强度的变化对东亚夏季降水年际变化具有重要影响。我们初步分析发现，SRT的中心位置和强度在1990s末发生了显著的年代际变化，这对东亚夏季降水产生了重要影响。目前，对于SRT这次年代际变化关注和研究较少。为此，本项目将通过资料分析、动力诊断和数值试验等手段，进一步深入地研究1990s末SRT年代际变化的特征，分析SRT在1990s末转变前后对东亚夏季降水的不同影响，探讨大气基本流、全球降水和海温异常在SRT这次年代际变化的作用和影响机制，揭示1990s末SRT年代际变化的内动力和外强迫成因。本项目研究成果将有助于更好地理解和认识SRT变异规律及其对东亚夏季降水的影响，并为提高东亚夏季气候预测能力提供新的科学依据。

"丝绸之路”型遥相关（Silk Road pattern; SRP）是影响东亚夏季气候和预测的关键系统之一。本项目利用观测、再分析数据和统计诊断分析方法，揭示出SRP空间结构在1990s末发生了显著的年代际转变。结果显示1990s末以来，SRP强度减弱，活动中心向东、向南偏移，它对东北亚地区夏季降水和气温的影响变强。进一步，研究指出1990s末SRP年代际变化是由于印度季风区东北部夏季降水变率增强以及欧亚地区基本流年代际减弱共同作用所导致的。本项目研究成果有助于更好地理解和认识SRP变异规律，对提高东亚夏季气候预测水平具有重要的科学意义。