Coupling of the Perkins instability and the sporadic E layer instability derived from physical arguments -: art. no. A06301
Coupling of the Perkins instability and the sporadic E layer instability derived from physical arguments -: art. no. A06301
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DOI：
10.1029/2003ja010295
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发表时间：
2004-06-10
影响因子：
2.8
通讯作者：
Yamamoto, M
中科院分区：
文献类型：
--
作者：
Cosgrove, RB;Tsunoda, RT;Yamamoto, M
Tsunoda和Cosgrove[2001]最近指出，鉴于ES层中存在霍尔极化过程，必须将夜间中纬度电离层中的F层和零星E(ES)层视为一个耦合系统[Haldoupis等人，1996；Tsunoda，1998；Cosgrove和Tsunoda，2001,2002a]，并且E和F区之间有效地映射了千米尺度的电场。他们还注意到，这些区域的进程之间存在明显的积极反馈。Cosgrove和Tsunoda[2002b，2003]已经证明E-S层是不稳定的，其性质与F区的Perkins不稳定性相似[Perkins，1973]，这激发了这两个不稳定性可能耦合的想法。最后，Cosgrove和Tsunoda[2004]导出了E-S层和F层耦合系统的线性增长率，从而实现了Perkins和E-S层不稳定性的统一形式。他们发现，这种耦合显著提高了增长速度。然而，Cosgrove和Tsunoda[2004]中计算的增长率仅表示为非常复杂的3x3矩阵的最大特征值。本文给出了E-F耦合层(EFCL)不稳定性的物理解释，并导出了最大耦合的条件。我们得到了一个耦合层系统的电路模型，它为层间电场映射的波长依赖性提供了物理解释，并允许进行定量预测。利用电路模型，我们从孤立的Perkins增长率和ESL不稳定性增长率导出了计算耦合系统两种增长率的“经验法则”，并与Cosgrove和Tsunoda[2004]的精确计算结果进行了比较。
Tsunoda and Cosgrove [ 2001] recently pointed out that the F layer and sporadic E (Es) layers in the nighttime midlatitude ionosphere must be considered electrodynamically as a coupled system in light of the presence of a Hall polarization process in Es layers [Haldoupis et al., 1996; Tsunoda, 1998; Cosgrove and Tsunoda, 2001, 2002a] and the fact that kilometer-scale electric fields map efficiently between the E and F regions. They further noted the apparent presence of positive feedback between processes in those regions. Cosgrove and Tsunoda [2002b, 2003] have since shown that E-s layers are unstable with properties not unlike those of the Perkins instability in the F region [ Perkins, 1973], motivating the idea that the two instabilities may couple. Finally, Cosgrove and Tsunoda [2004] derived the linear growth rate for the coupled system of a E-s layer and the F layer, thus realizing a unified formalism for the Perkins and E-s layer (EsL) instabilities. They found that the growth rate was significantly enhanced by the coupling. However, the growth rate computed in Cosgrove and Tsunoda [ 2004] was expressed only as the largest eigenvalue of a very complex 3 x 3 matrix. In this paper we present a physical interpretation of the E-F coupled-layer (EFCL) instability, and derive the condition for maximal coupling. We obtain a circuit model for the coupled-layer system that provides a physical interpretation for the wavelength dependence of electric field mapping between layers, and allows quantitative predictions. Using the circuit model we derive a "rule of thumb'' for computing the two growth rates of the coupled system from the isolated Perkins and EsL instability growth rates. We compare the result with the exact computation of Cosgrove and Tsunoda [ 2004].