On the production mechanism of electric currents and fields in the ionosphere
On the production mechanism of electric currents and fields in the ionosphere
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DOI：
10.1029/ja081i004p00547
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发表时间：
1976-02
影响因子：
--
通讯作者：
A. Richmond;S. Matsushita;J. D. Tarpley
中科院分区：
文献类型：
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作者：
A. Richmond;S. Matsushita;J. D. Tarpley
发电机理论的Sq变化的重新审查，看看它是否可以调和与最近的观测电离层风和电场。发电机模拟进行使用稳定的风和昼夜和半日潮汐风，观测和理论证据被用来指定的振幅和相位随高度的变化的风。我们发现，第一个负的昼夜潮汐模式，目前在上E和下F地区的电离层，是能够占大部分的Sq电流。这种潮汐的结构，我们称之为（1，−2）* 模式，受到离子拖曳力的显著影响。低E区风，最显着的半日（2，4）潮汐模式，也有助于一定的Sq电流。我们用（1，−2）* 和（2，4）模式模拟的电场与观测值相当一致;电离层风的不确定性以及从观测值中获得静日平均电场的误差可以很容易地解释其余的差异。白天电场的逐日变化可能与E区风的变化有关。对假设的磁层源在平静时期引起的电流和场的模拟表明，单靠这种源不能解释观测到的大部分中低纬度电流和场，至少在白天是这样。要澄清其余的问题，需要进一步的观察和理论工作。
The dynamo theory of Sq variations is reexamined to see if it can be reconciled with recent observations of ionospheric winds and electric fields. Dynamo simulations are performed by using steady winds and both diurnal and semidiurnal tidal winds, observational and theoretical evidence being used to specify the amplitude and phase variations of the winds with altitude. We find that the first negative diurnal tidal mode, present in the upper E and lower F regions of the ionosphere, is capable of accounting for most of the Sq currents. The structure of this tide, which we call the (1, −2)* mode, is significantly influenced by the ion drag force. Lower E region winds, most notably the semidiurnal (2, 4) tidal mode, also contribute somewhat to the Sq currents. Our simulated electric fields using the combined (1, −2)* and (2, 4) modes are in fair agreement with observations; uncertainties in the ionospheric winds as well as errors in obtaining quiet day mean electric fields from the observations can easily account for the remaining discrepancies. Day-to-day variations in the daytime electric fields are probably related to variability of the E region winds. A simulation of electric currents and fields caused by hypothesized magnetospheric sources at quiet times shows that such sources alone cannot account for most of the observed middle- and low-latitude currents and fields, at least during daytime. Clarification of remaining problems requires further observational and theoretical work.