大气动力学中三种Rossby波作用通量的特征差异和适用性比较

大气动力学诊断Rossby波的传播时,通常用波作用通量来表示。常用的三种波作用通量分别为Plumb波作用通量,T-N波作用通量和局地E-P通量。本文详细讨论了这三种方法的特征差异,并结合2016年1月的一次寒潮事件,比较了三种方法在该事件中的适用性。结果表明:1)Plumb波作用通量的纬向分量较大而经向分量较小,适用于振幅较小的纬向均匀的西风带Rossby长波的诊断。2)T-N波作用通量是对Plumb波作用通量的改进,经向分量得以增强,能更好地描述纬向非均匀气流中的较大振幅的西风带Rossby长波扰动。T-N波作用通量计算时,背景场取多年平均的当月气候场较合适,能更好地反映当前季节内的Rossby波传播异常。3)局地E-P通量可以诊断一段时间内天气尺度瞬变波对背景场(定常波)总的调控作用,但无法直接反映Rossby长波的逐时演变(T-N波或Plumb波作用通量则可以)。

The differences in characteristics and applicability among three types of Rossby wave activity flux in atmospheric dynamics

Plumb wave activity flux,T-N wave activity flux and local E-P wave activity flux are widely used to analyze the propagation of Rossby wave in atmospheric dynamics.The differences in characteristics and applicability among three types of Rossby wave activity fluxes are discussed in a case study of a cold wave in January 2016.Plumb wave activity flux with strong zonal component and weak meridional component is suitable for the analysis of Rossby waves with small amplitude in the zonally symmetric westerly.T-N wave activity flux with improved meridional component based on Plumb wave activity flux is appropriate for analyzing Rossby waves in the zonally asymmetric westerly.T-N wave activity flux derived on the multi-year average climatic field of current month can more successfully indicate wave propagation anomaly in current season.Local E-P wave activity flux can illustrate the modulating effect of transient waves on background field (stationary waves),but can not reflect the evolution of long waves.