Investigation of the formation of the Polar-night Jet Oscillation and troposphere-stratosphere dynamical coupling

极夜急流振荡（PJO）是平流层突然变暖（SSW）和涡旋加强（VB）准周期性发生的一种现象。发现PJO以如下方式发生：从表面传播到平流层的行星波的产生强烈地受异常表面压力以及表面中的纬向流的控制。特别是当纬向平均纬向风偏北时，Fliassnn-Palm（E-P）通量的垂直分量有增强的趋势。一般来说，在SSW发生之前，地面气压场与北极涛动（AO）的正型非常相似。这种行星波在对流层有较大的振幅，它们通过波-平均流相互作用在平流层产生较大的波强迫，并产生异常东风。同时，波的活动在极盖产生向下的余流，在热带产生向上的余流。 ...更多信息 e强迫，这正好对应于SSW的发生。这种极盖高温区逐渐扩大，幅度逐渐减小。与此同时，高纬异常东风区通过热成风关系与极冠高温区相联系，并通过纬向环流的活动对平流层低层和地面产生影响。当异常东风到达地面时，地面气压异常指示AO的负型，地面异常纬向风转向南风。在这些条件下，地面行星波的振幅减小，平流层中的波活动变得比正常情况下弱。由于平流层中的这种较小的波动活动，波驱动的剩余环流的活动变得较弱，并在极盖处产生VI。与VI相关的极盖温度异常和高纬向风异常与SSW一样随时间下降，当异常纬向风到达地面时，产生AO正型。以这种方式，初始条件被再现。这显示了像PJO这样的循环现象是如何通过波-平均流相互作用和纬向环流产生的。少

Polar-night Jet Oscillation (PJO) is a phenomenon that is made by the quasi-periodic occurrence of the stratospheric sudden warming (SSW) and the vortex intensification (VB. PJO is found to occur in the follow way: Generation of planetary waves that propagate from the surface to the stratosphere is strongly controlled by anomalous surface pressure as well as meridional flow in the surface. Especially, if zonal-mean meridional winds are northward, vertical component of the Fliassnn-Palm (E-P) flux have a tendency to be enhanced. Generally, surface pressure pattern before the occurrence of the SSW is very similar to the positive pattern of the Arctic Oscillation (AO). Such planetary waves have larger amplitude in the troposphere and they produce larger wave forcing in the stratosphere through wave-mean flow interaction and produce anomalous easterly wind. At the same time, downward residual flow at the polar cap as well as upward flow at the tropics is produced by the activity of the wav … More e-forcing and this just corresponds to the occurrence of the SSW. Such higher temperature area at the polar-cap gradually dasonnds with reducing amplitude. At the same time, anomalous easterly area at high latitude, which is associated with higher temperature area at the polar-cap through thermal wind relationship, also de mends to the lower stratosphere and also to the surface through the activity of the meridional circulation. When anomalous easterly wind reaches the surface, anomalous surface pressure indicates negative pattern of the AO and anomalous meridional wind at the surface shifted to southward wind. From these conditions, amplitude of the planetary waves at the ground is reduced and wave activity in the stratosphere becomes weaker than normal. By such smaller wave activity in the stratosphere, activity of wave driven residual circulation becomes weaker and produces VI at the polar-cap. Anomalous temperature at the polar-cap and zonal wind at high-latitude associated with VI descends with time as in the SSW and creates positive pattern of the AO when anomalous zonal wind reaches the surface. In such a way, initial condition is reproduced. This shows how the cyclic phenomenon like PJO is created through wave-mean flow interaction and the meridional circulation. Less