平流层环流在北极海冰对北半球冬季气候影响中的作用

Recent studies have revealed tight connections among the Arctic sea ice, stratospheric circulation, and boreal winter surface climate over multiple spatial and temporal scales. However, there are still debates on the dynamics behind these connections. Since many of these studies are based on numerical simulations using coupled atmosphere-ocean-ice models, it is relatively difficult to separate out the pathway and feedback directions of the forced signals. Therefore, it is proposed to analyze observations and reanalysis data with the aid of a quasi-stationary wave model developed from the dynamical core of a general circulation model, in order to illustrate the winter time atmospheric circulation and surface climate response to Arctic sea ice anomalies. The advantage of this simple model in separating the planetary wave response to the zonally symmetric and asymmetric anomalies helps clarify the propagation of signals and the corresponding feedback mechanisms. This project will investigate the interannual variability and long-term trends of boreal winter climate using monthly and seasonal mean data, and aims to provide new insights for improving the forecast skill of winter surface climate in China and other extratropical regions in the northern hemisphere.

北极海冰、平流层大气环流和北半球冬季地面气候三者相互之间有着非常紧密的联系，而且这种相互关系表现在多个时空尺度上。但是对这些相互作用的认识并不充分，尤其是对其中的动力学过程仍有较大争议。现有研究成果大多数基于气海冰耦合气候模式的数值模拟，不易分离出清晰的信号传播路径和方向。本项目将利用一个基于大气环流模式的动力核心开发出的准定常波模式来分析观测资料和再分析资料中北极海冰对北半球冬季大气环流以及地面气候的强迫作用，尤其是平流层环流对该强迫的相应和反馈情况，对纬向平均流和波动进行进一步分解，以厘清其中信号的传播过程和动力学反馈机制。本项目主要运用月、季平均资料考察冬季气候的年际变率和长期趋势及其成因，为进一步提高中国及北半球冬季气候预报技巧提供新的方向和思路。