The coupled stratosphere-troposphere response to impulsive forcing from the troposphere
The coupled stratosphere-troposphere response to impulsive forcing from the troposphere
复制标题
对流层脉冲强迫的平流层-对流层耦合响应
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
L. Polvani
中科院分区：
文献类型：
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作者：
T. Reichler;P. Kushner;L. Polvani
本文采用简单大气环流模式（GCM）研究了平流层-对流层系统对对流层低层行星波活动脉冲的瞬态响应。大气GCM是一个干燥的、流体静力的、全球原始方程模式，其环流包括一个活跃的极涡和一个斜压涡旋维持的对流层急流。行星波活动脉冲是由固体下边界的扰动产生的，在10天的时间内增长和衰减。行星波脉冲向上传播并在平流层中断。随后，纬向平均环流异常向下传播，通常滞后30-100天进入对流层。发现响应的演变取决于脉冲产生时平流层-对流层系统的状态。特别是，在这些模拟的大集合的基础上，发现信号从平流层向下传播的时间长度是由纬向平均环流和纬向平均波阻力的初始异常控制的。因此，基于这些异常模式的标准可用于预测平流层-对流层系统对行星波脉冲产生后90天内的长期地表响应。在一个独立的测试中，证实了最强烈满足这些标准的初始状态以预期的方式响应对流层低层波活动脉冲。
A simple atmospheric general circulation model (GCM) is used to investigate the transient response of the stratosphere–troposphere system to externally imposed pulses of lower-tropospheric planetary wave activity. The atmospheric GCM is a dry, hydrostatic, global primitive-equations model, whose circulation includes an active polar vortex and a tropospheric jet maintained by baroclinic eddies. Planetary wave activity pulses are generated by a perturbation of the solid lower boundary that grow and decay over a period of 10 days. The planetary wave pulses propagate upward and break in the stratosphere. Subsequently, a zonal-mean circulation anomaly propagates downward, often into the troposphere, at lags of 30–100 days. The evolution of the response is found to be dependent on the state of the stratosphere– troposphere system at the time the pulse is generated. In particular, on the basis of a large ensemble of these simulations, it is found that the length of time the signal takes to propagate downward from the stratosphere is controlled by initial anomalies in the zonal-mean circulation and in the zonal-mean wave drag. Criteria based on these anomaly patterns can be used, therefore, to predict the long-term surface response of the stratosphere–troposphere system to a planetary wave pulse up to 90 days after the pulse is generated. In an independent test, it is verified that the initial states that most strongly satisfy these criteria respond in the expected way to the lower-tropospheric wave activity pulse.