冬季欧亚次季节气候的变化成因及预测模型研究

Concurrent with the global warming and Arctic warming, the phenomenon of Eurasian cooling winters with frequent extreme cold temperatures are topics of intense research but the associated physical mechanisms are controversy. Additionally, observations and previous studies indicate that the Eurasian winter climate has non-negligible diversity on the sub-seasonal time scale, which brings great challenges to climate prediction. Therefore, further understanding the mechanisms of the sub-seasonal change in Eurasian winter climate and establishing statistical-dynamic prediction models on the Eurasian sub-seasonal climate are important scientific issues. In view of the above scientific issues, the project plans to carry out the following research. Firstly, we explore the dominant features of the Eurasian monthly mean temperature and extreme temperature. Secondly, by utilizing the large-scale atmospheric variables and external forcing variables, we explore the physical mechanisms of the sub-seasonal change in Eurasian winter climate, to obtain the preceding and simultaneous impact factors. Thirdly, utilizing the latest prediction and hindcast datasets provided by international workgroups, we estimate the predict skills of global climate models on the Eurasian sub-seasonal climate and atmospheric circulation, to obtain the factors that are closely related to the simultaneous Eurasian sub-seasonal climate and can be predicted by global climate models. Finally, the statistical-dynamic prediction models on the Eurasian sub-seasonal climate will be established to predict Eurasian sub-seasonal climate. This project will contribute to further understanding of the diversity in regional climate to the global warming and improvement of the prediction skills on the Eurasian winter climate, and provide new prediction model for Eurasian winter climate.

随着全球和北极变暖，欧亚冬季气候变冷、极端低温频发现象成为国际气候研究领域的新热点，但关于其形成机制依然存在较大分歧。同时，观测事实表明，欧亚冬季气候在次季节尺度上存在较大差异，给气候预测带来巨大挑战。进一步认识冬季欧亚次季节气候的变化机理、区别建立其统计—动力相结合的预测模型是亟待解决的科学问题。因此，本项目计划：1）针对冬季欧亚次季节平均气温和极端气温，研究欧亚次季节气候的时空变化规律；2）结合大气环流场、外强迫数据，研究冬季欧亚气候在次季节尺度上变化的物理机制，筛选其前期、同期的影响因子；3）充分利用国际上最新的气候预测/回报试验，研究全球气候模式对欧亚冬季气候及相关大气环流场的预测效能；筛选同期且模式具有预测技巧的大气环流系统；4）区别建立欧亚次季节气候的动力—统计的预测模型并开展预测试验。本项目旨在深入认识全球变暖背景下的区域气候变化的差异性、为未来欧亚气候预测提供新的预测模型。

随着全球和北极变暖，欧亚冬季气候变冷、极端低温频发现象成为国际气候研究领域的新热点，但关于其形成机制依然存在较大分歧。同时，观测事实表明，欧亚冬季气候在次季节尺度上存在较大差异，给气候预测带来巨大挑战。进一步认识冬季欧亚次季节气候的变化机理、区别建立其统计—动力相结合的预测模型是亟待解决的科学问题。.围绕观测事实及关键科学问题，本项目重点开展了以下研究：1）针对我国前冬与后冬平均气温和极端气温异常的反转现象，研究其与热带中东太平洋的联系；2）围绕大尺度大气环流模态如北大西洋涛动等、外强迫因素如人为因素和太阳风能量通量等，研究了冬季欧亚气候在次季节尺度上变化的物理机制，确定其前期、同期的影响因子；3）充分利用国际上最新的气候预测/回报试验，研究了全球气候模式对北极海冰、北极增暖-欧亚偏冷气候模态、阻塞高压等大气环流场的模拟能力，明晰了预测建模的理论基础； 4）利用机器学习方法，对东亚冬季逐月气温分别建立了预测模型，并开展了回报试验，其预测技巧高于动力预测模型。本项目如期完成研究计划、实现了预定的研究目标：深入认识全球变暖背景下的区域气候变化的差异性、为未来欧亚气候预测提供新的预测模型。