东北地区典型旱涝年份大气环流异常的形成机理和预测研究

More frequent extreme flood and drought disasters affected Northeast China (NEC), and caused huge losses in recent years. The mechanism is complicated, especially under the influences of global warming and decadal variability. The real-time prediction accuracy rate is low, which can’t meet the actual demand of disaster prevention and mitigation. The objectives of this project are: to reveal the features of typical flood and drought summer in the NEC through analyses on the field measurement and the reanalysis datasets, and the possible mechanisms behind; to identify the possible process and impact factors for the typical flood and drought summer through comprehensive studies including numerical simulation and data analyses; to establish statistical and dynamical hybrid prediction model for the summer rainfall activity in NEC via statistical downscaling method, and perform verification of the model; to improve the skill of real-time prediction for NEC summer precipitation.

近年来我国东北地区极端旱涝灾害的影响愈加突出，严重制约了当地农业生产和社会经济发展。其发生机理相当复杂，特别是在全球变暖和气候年代际变化的影响下，旱涝的实时预测准确率较低，远不能满足国家防灾减灾的实际需求。本项目拟通过对气象测站资料和再分析资料的分析研究，揭示我国东北地区典型旱涝年份大气环流异常的基本特征及其与主要大气环流模态、海温、海冰等的可能联系；结合大气模式（CAM5）的模拟试验，揭示东北地区典型旱涝年份大气环流异常的关键下垫面因子及其可能影响机制，提取具有明确物理内涵的前期预测因子；分析气候模式对于东北地区典型旱涝年份气候异常的回报效能，提取具有数值预测技巧的同期预测因子，通过统计降尺度方法构建统计－动力相结合的东北夏季降水的预测模型，并进行科学检验，以期提高我国东北地区夏季降水的实时预测准确率。

东北夏季降水的变异是我国夏季气候预测的难点，动力预测系统的预测性能普遍很低。本项目通过对东北地区夏季降水变异特征和机理的分析，揭示了影响东北夏季降水的前期海温和海冰因子；基于中国多模式预测系统（CMME）的四个气候预测系统，发展了适合于东北地区夏季降水的统计—动力相结合的预测方法，系统性地回报检验结果显示，该方法可以有效提升模式对于东北夏季月降水的预测能力。相关成果发表学术论文两篇，其中SCI一篇,完成了项目的预期目标。