Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking
Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking
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DOI：
10.1002/jgrd.50374
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发表时间：
2013-05-27
影响因子：
4.4
通讯作者：
Phillips, Tony
中科院分区：
文献类型：
--
作者：
Lu, Hua;Franzke, Christian;Phillips, Tony
我们提供了太阳风动压（P-sw）对北方冬春季环流影响的统计证据。我们发现，垂直结构的北方环状模（NAM），纬向平均环流，和Eliassen-Palm（EP）-通量异常显示了一个动态一致的模式，向下传播超过一个类似的45天的一段时间，以响应正P-sw异常。当太阳辐照度高时，P-sw的特征是在冬季由平流层下降到地面的正NAM异常。当太阳辐照度较低时，P-sw信号具有相反的符号，发生在春季，并且局限于平流层。在低太阳辐照度条件下，NAM中的负P-sw信号主要由增强的垂直EP通量散度和较温暖的极地区域决定。冬季高太阳辐射条件下的P-sw信号与55 ° N-75 ° N的水平EP通量散度的正异常和25 ° N-45 ° N的负异常相关联，这对应于正NAM异常。EP通量辐散异常比平均流量变化提前15天左右。1月至3月期间，对流层顶附近的天气尺度罗斯贝波破碎（RWB）明显向赤道移动，对应于反气旋RWB的增加和气旋RWB的减少。我们认为，正压不稳定与平流层上部的非对称臭氧和斜压不稳定与极涡在平流层中，下部的冬季信号及其向下传播起着关键作用。
We provide statistical evidence of the effect of the solar wind dynamic pressure (P-sw) on the northern winter and spring circulations. We find that the vertical structure of the Northern Annular Mode (NAM), the zonal mean circulation, and Eliassen-Palm (EP)-flux anomalies show a dynamically consistent pattern of downward propagation over a period of similar to 45days in response to positive P-sw anomalies. When the solar irradiance is high, the signature of P-sw is marked by a positive NAM anomaly descending from the stratosphere to the surface during winter. When the solar irradiance is low, the P-sw signal has the opposite sign, occurs in spring, and is confined to the stratosphere. The negative P-sw signal in the NAM under low solar irradiance conditions is primarily governed by enhanced vertical EP-flux divergence and a warmer polar region. The winter P-sw signal under high solar irradiance conditions is associated with positive anomalies of the horizontal EP-flux divergence at 55 degrees N-75 degrees N and negative anomalies at 25 degrees N-45 degrees N, which corresponds to the positive NAM anomaly. The EP-flux divergence anomalies occur similar to 15days ahead of the mean-flow changes. A significant equatorward shift of synoptic-scale Rossby wave breaking (RWB) near the tropopause is detected during January-March, corresponding to increased anticyclonic RWB and a decrease in cyclonic RWB. We suggest that the barotropic instability associated with asymmetric ozone in the upper stratosphere and the baroclinic instability associated with the polar vortex in the middle and lower stratosphere play a critical role for the winter signal and its downward propagation.