Atmospheric Blocking: Dynamics and Responses to Climate Change

大气阻塞事件是高影响极端天气事件的重要贡献者。改善阻塞事件的预测和评估这些事件的频率、严重程度和位置如何随着气候变化而变化具有重大的社会意义。天气涡旋已被证明在大气阻塞事件的动力学中起着关键作用，通过维持阻塞模式，但目前对其作用的理解还不够完整和定量。拟议研究的目标是：1）通过对阻塞的天气涡旋强迫进行定量评估，提高对大气阻塞事件的动力学理解。2)利用这种动态的理解来研究阻塞事件如何随着气候变化而变化，以及如何在气候和天气模型中更好地模拟阻塞。拟议的研究将采用数值实验与层次的大气环流模型，再分析数据，以及存档的结果，全物理大气环流模型，如耦合模型相互比较项目模型。研究有三个组成部分：第一个是研究涡强迫机制，使用理想化的模拟实验，隔离和发展定量的了解这种机制。同样的理想化的框架将被用来研究如何的速度和纬度的急流，准定常行星波的不同模式，和水分调制这一机制。第二个组成部分是使用再分析数据来测试这种理解，并进一步深入了解观测到的阻塞事件的动态。第三个组成部分是应用这种理解来检查全物理模型在模拟阻塞方面的性能，并对阻塞事件在未来将如何变化提供更可靠和结论性的预测。

Atmospheric blocking events are an important contributor to high impact extreme weather events. Improving the forecasts of blocking events and assessing how the frequency, severity, and location of such events may change with climate change are of substantial societal importance. Synoptic eddies have been shown to play a critical role in the dynamics of atmospheric blocking events by maintaining the blocking pattern but the understanding of their role is currently not sufficiently complete and quantitative. The goals of the proposed research are 1) to improve the dynamical understanding of atmospheric blocking events through developing a quantitative assessment of synoptic-eddy forcing of blocks. 2) to employ this dynamical understanding to investigate how blocking events will change with climate change and how blocks can be better simulated in climate and weather models. The proposed research will employ numerical experiments with a hierarchy of general circulation models, reanalysis data, and archived results of full-physics general circulation models such as Coupled Model Intercomparison Project models. The research has three components: the first is to study the eddy-forcing mechanism using idealized modeling experiments which to isolate and develop a quantitative understanding of this mechanism. The same idealized framework will be used to investigate how the speed and latitude of jet streams, different patterns of quasi-stationary planetary waves, and moisture modulate this mechanism. The second component is to test this understanding using the reanalysis data and to gain further insight into the dynamic of observed blocking events. The third component is to apply this understanding to examine the performance of full-physics models in simulating blocking, and to provide a more reliable and conclusive prediction on how blocking events will change in the future.