Eddy Feedbacks on the Zonal Index and Eddy–Zonal Flow Interactions Induced by Zonal Flow Transience
Eddy Feedbacks on the Zonal Index and Eddy–Zonal Flow Interactions Induced by Zonal Flow Transience
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分区指数的涡流反馈和分区流瞬变引起的涡流-分区流相互作用
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
W. Robinson
中科院分区：
文献类型：
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作者：
W. Robinson
摘要本文用一种机械方法来确定瞬变涡动反馈对纬向对称低频变率的性质和频率依赖性。一个简单但完全非线性的大气模式的纬向动量是由一个周期强迫驱动的。在没有强迫的情况下，这是一个自发产生低频纬向对称变率的模式。对强迫的响应由纬向流的瞬态涡动驱动的幅值和相位决定，这强烈地依赖于强迫频率。在短时间内，不到30天，驱动纬向流的瞬变涡滞后纬向角动量超过四分之一周期，因此，是一个负反馈。随着周期的增加，涡驱动变得更加与角动量同相，并且对于稳定施加的强迫，涡反馈是强正的。这些结果与高频抑制是一致的。
Abstract A mechanistic approach is used to determine the nature and frequency dependence of transient eddy feedbacks on zonally symmetric low-frequency variability. The zonal momentum of a simple though fully nonlinear atmospheric model is driven by an imposed periodic forcing. In the absence of the imposed forcing this is a model that spontaneously generates its own low-frequency zonally symmetric variability. The response to the imposed forcing is determined by the amplitude and phase of the transient eddy driving of the zonal flow, which depends strongly on the imposed forcing frequency. At short periods, less than 30 days, the driving of the zonal flow by transient eddies lags the zonal angular momentum by more than a quarter-cycle and is, therefore, a negative feedback. As the period is increased, the eddy driving becomes more in phase with the angular momentum, and for steady imposed forcing the eddy feedback is strongly positive. These results are consistent with the suppression of high frequencies...