中高纬平流层环流对冬春季对流层天气气候的影响

The coupling of stratosphere and troposphere and its impact on tropospheric weather and climate are currently a frontier research field in the world. How to reliably predict tropospheric climatic changes in the winter and spring in the northern hemisphere months ahead is a challenge for climate research. This project will focus on the impact of stratospheric circulation in mid-high latitudes on the tropospheric climate over the winter and spring, and explore the three-dimensional characteristics of the stratospheric circulation anomalies that can significantly affect the tropospheric weather. It will reveal the differences in the influence of the anomalous events of the stratospheric circulation in winter and spring on the troposphere. To clarify the connections between the seasonal transition of the stratosphere and the troposphere circulation in the mid-high latitude, this project will explore the mechanism for such connections. This project will provide scientific basis for the development of tropospheric weather forecasting and short-term climate prediction. Hopefully, it will put forward stratospheric indicators that can predict the seasonal transition of tropospheric circulation. Previous work mostly looked for the factors that predict the seasonal transition of the tropospheric circulation from the ocean-troposphere coupling system. This project intends to further introduce the stratospheric signals in order to improve the prediction of the seasonal transition in the tropospheric circulation, thus this project is with innovation.

平流层与对流层的耦合及其对对流层天气气候的影响是目前国际上的一个前沿研究领域。如何提前数月可靠地预测北半球冬春季对流层气候变化是气候研究面临的挑战。本项目将以中高纬度平流层环流对冬春季对流层天气气候的影响为主体研究内容，探索能够明显地影响对流层天气的平流层环流异常具有怎样的三维特征，揭示平流层环流的异常事件在冬季和春季对对流层的影响有何差异，阐明中高纬度平流层环流的季节转换与对流层环流的季节转换的联系以及存在这种联系的机制，以加深我们对平流层影响对流层天气气候的认识，为对流层天气的延伸预报和短期气候预测提供科学依据，提出能够预报对流层环流季节转换的平流层指标。以往的工作多从海洋-对流层大气耦合系统中寻找预测对流层环流季节转换的因子，本项目研究拟进一步引入平流层信号以便提高对流层环流季节转换的预测水平，具有特色和创新。

本研究探索了能够明显地影响对流层天气的平流层环流异常具有怎样的特征。平流层爆发性增温的剧烈扰动常给欧亚大陆和北美地区带来寒潮，其变化近年来引起了公众和新闻媒体的广泛关注。由于强爆发性增温状态下开展的数值预报可为对流层天气预测提供次季节尺度的参考，因此平流层爆发性增温受到科学界的重视。本研究发现伴随着1980年前后遥相关组合发生的年代际的变化，平流层爆发性增温的频数，强度和持续时间也发生了显著的增强。该研究结果增强了再分析资料研究所得平流层爆发性增温变强结论的可信度。研究也发现由于气候平均的热带中东太平洋对流活动较弱，其对流对平流层环流的作用往往被人们所忽视。然而，该处最近70年对流活动增加了20%左右，对冬季北半球平流层的气候变化具有重要的影响。本研究不足的是关于平流层如何影响对流层的机制还有待进一步完善。