| 中、低纬度地区电离层不同层结间的耦合对夜晚F区不规则结构的影响 |
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| 引用本文： | 张天华,肖佐.中、低纬度地区电离层不同层结间的耦合对夜晚F区不规则结构的影响[J].地球物理学报,2000,43(5):589-597. |
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| 作者姓名： | 张天华 肖佐 |
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| 作者单位： | 北京大学地球物理系,北京100871 |
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| 基金项目： | 国家自然科学基金资助项目! (4 9990 4 54，4 9874 0 4 1 ) |
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| 摘 要： | 电离层不规则结构的形成和演化与电离层等离子体不稳定性密切相关 .长期以来 ,在中低纬区扩展 -F现象的研究中 ,没有考虑电离层上下层结之间的相互作用 .本文从理论上全面探讨了在中纬度地区 ,E区可变的Pedersen电导率和Hall电导率 ,与F区可变的Pedersen电导率的共同作用对F区梯度漂移不稳定性的影响 ,导出了存在这种耦合时电离层梯度漂移不稳定性的统一表达式 .这一耦合理论不但解释了实际观测中发现的 ,在某些地方电离层F区顶部的不稳定性发生率要高于F区底部这一现象 ;同时还表明 ,电离层E区与F区的耦合对F区夜晚梯度漂移不稳定性的形成不仅会有阻碍作用 ,同时还使得中、低纬度地区的扰动增长具有了方向的选择性 .该理论的一个重要结论是 ,F区中某一地区能否发展出梯度漂移不稳定性 ,并不完全由当地电离层F区的状态决定 ,同一根磁力线连接的、位于不同纬度地区的E区层结对其发展和演化也会有相当大的影响 .
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| 关 键 词： | 电离层等离子体不稳定性 电离层耦合 电离层电导率 扩展-F |
| 收稿时间： | 1999-12-07 |
EFFECT OF THE COUPLING OF DIFFERENT IONOSPHERIC REGIONS ON THE NIGHTTIME F REGION IRREGULARITIES IN MID-LOW LATITUDES |
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| ZHANG TIAN-HUA,XIAO ZUO.EFFECT OF THE COUPLING OF DIFFERENT IONOSPHERIC REGIONS ON THE NIGHTTIME F REGION IRREGULARITIES IN MID-LOW LATITUDES[J].Chinese Journal of Geophysics,2000,43(5):589-597. |
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| Authors: | ZHANG TIAN-HUA XIAO ZUO |
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| Institution: | Department of Geophysics,Peking University, Beijing 100871,China |
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| Abstract: | The formation and evolution of ionospheric irregularities are closely connected with the instabilities of ionospheric plasma. However, no much consideration of the coupling between upper and lower parts of the ionosphere has ever been taking into account so far in the study of such instabilities in mid and low latitudes. In this paper, a full discussion was presented on the roles played by the existence of both E region Pedersen and Hall conductivity and F region Pedersen conductivity. A complete and common expression of ionospheric plasma gradient drift instability under such a coupling was deduced for mid and low latitudes based on a three layer model developed earlier only valid for high latitude area. With this model, the observed phenomenon that in some places, the instability occurrence rate is higher in the top F region than in the bottom side can be explained well. Besides, the model also shows that the evolution of nighttime F region gradient drift instability will be slowed down due to the coupling between E and F regions and make the instability growth rate vary with directions in mid latitude. It is concluded that the development of gradient drift instability in nighttime F region not only depends on the local conditions, but also is affected by state of E region that connected to F region with the geomagnetic field lines. |
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| Keywords: | Ionosphere plasma instability Ionosphere coupling Ionosphere conductivity Spread F |
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