我国西南地区冬春季区域气候差异特征分析和模拟研究

The southwest region of China located in the southeast margin of the Qinghai-Tibet plateau. Influenced by the Qinghai-Tibet plateau terrain and local complex terrain, the regional climate in the Southwest region is significant different, especially in winter and spring seasons. In winter and spring seasons, the rainfall is abundant in the Midwest Hengduan Mountains and the spring is the season of most rainfall. At the same time, it is the driest season for the east Hengduan Mountains, where seasonal droughts often occur. In the further east region, with the frequent appearance of the Yunnan-Guizhou quasi-stationary, it rains often, though with little rainfall amount. With the significant regional climatic differences in west, middle, and east areas, previous studies pay less attention to the relation between the climate differences of three regions. . Our project plans to make a meticulous analysis of these regional climatic differences, such as precipitation, temperature, humidity, with observation data in high temporal and spatial resolution; next, explore the formation mechanism of these differences from the perspectives of atmospheric circulation, such as Southern Branch Trough and Yunnan-Guizot Quasi-Stationary Front; at last, design numerical experiments by regional climate model, the role of terrain, and surface sensitive heating flux etc. will be analyzed.

位于青藏高原东南缘的我国西南地区，受青藏高原大地形和局地复杂地形的共同影响，区域气候差异显著，冬春季尤为突出。在冬春季，横断山脉中西部地区降水丰沛，春季达到季节降水峰值；而横断山脉东部的滇中北地区却是一年之中最干的时候，并时常发生冬春季节性干旱；再往东的云贵高原地区，云贵准静止锋活动频繁，虽降水强度小，但降水频次很高。围绕西南地区西、中、东三个区域的气候差异特征，此前研究较少关注三个区域的气候差异特征之间的联系。本项目拟利用研究区域内的200多个国家级气象观测站60余年来高时空分辨率的观测资料，从降水、温度、湿度等方面全面给出气候区域差异特征；再通过对南支槽和云贵准静止锋等典型天气过程的个例和合成的诊断分析，给出形成显著气候区域差异的原因；并利用区域气候模式，结合典型过程，设计数值试验，通过修改地形、地面感热通量等敏感性试验，验证诊断分析的结论，丰富对西南地区气候特征的认识。

位于青藏高原东南缘的我国西南地区，受青藏高原大地形和局地复杂地形的共同影响，区域气候差异显著，冬春季尤为突出。本项目围绕我国西南地区冬春季区域气候差异特征，展开了分析和模拟研究，揭示了其主要特征和物理机制。主要成果有：（1）西南地区冬春季西、中、东三个区域独特的气候差异特征在各个气象要素上的体现，特别是中部显著的干季特征。（2）分析了大气环流和地形在形成气候区域差异特征上扮演的角色，西部的横断山脉与东部的云贵高原，两个大地形与西路和东路天气系统的共同作用，形成了独特的区域差异。（3）利用区域气候模式对西南地区区域气候差异进行了模拟和研究，模式能再现西南地区气候的区域差异，敏感性试验也能反映和验证地形的作用与区域气候差异的联系。（4）研究西南地区干湿季节性差异和区域干旱洪涝演变关系，从降水结构的变化上指出了近些年西南地区干季干旱化趋势加重及其与雨季强降水变化之间的关系，揭示了旱涝灾害俱增趋势的气象条件。上述成果提高了对西南地区气候区域差异的认识，揭示了我国西南地区冬春季气候差异的物理机制，为提高对我国西南区域气候及其变化特征的理解和预测能力提供了科学依据，为应对和适应气候变化提供了科技支撑。