Investigation of the Poleward Propagation of the Zonal Mean Flow

本项目的目的是确定纬向平均气流异常向极地传播的动力机制，该异常被定义为与气候气流的偏差。这一现象在观测和数值模型研究中都得到了证实。最近的一项观测研究表明，这种现象无处不在，在南北半球的夏季和冬季都会出现。有理由怀疑这一现象可能是众所周知的低频异常或遥相关模式的重要组成部分，特别是所谓的北极涛动。受最近一项关于哈德利环流对罗斯比波动动力学影响的研究的启发，李博士提出了一个假说，即驱动极地传播的机制。该假设的实质是基于这样一个前提：异常斜压波通量驱动异常的Hadley环流，进而影响随后发生斜压波破裂的纬度。波-均流相互作用理论认为，这一过程必然会改变纬向平均流变化的经向分布，而这种变化最初是由涡旋通量驱动的。这项研究将探索这一过程如何导致纬向平均流涡的极地传播。研究将通过观测数据分析和数值模拟实验来完成。

The objective of this project is to determine the dynamical mechanisms responsible for the poleward propagation of zonal mean flow anomalies, where the anomaly is defined as the deviation from the climatological flow. The phenomenon has been identified in both observational and numerical model studies. A recent observational study showed that this phenomenon is ubiquitous, appearing in both the summer and winter seasons of the Northern and Southern Hemispheres. There are reasons to suspect this phenomenon may be an important part of well-known low-frequency anomalies or teleconnection patterns, particularly the so-called Arctic Oscillation. Inspired by a recent study on the impact of the Hadley circulation on Rossby wave dynamics, Dr. Lee developed a hypothesis for the mechanism that drives the poleward propagation. The essence of the hypothesis is based on the premise that anomalous baroclinic wave fluxes drive an anomalous Hadley circulation, and this in turn influences the latitude at which subsequent baroclinic wave breaking occurs. The theory of wave-mean flow interaction says that this process must alter the meridional distribution of the zonal mean flow change, which was initially driven by the eddy fluxes. This research will explore how this process can cause the poleward propagation of the zonal mean flow eddies. The investigation will be done through both observational data analysis and numerical modeling experiments.