Equinoctial asymmetry of ionospheric vertical plasma drifts and its effect on F‐region plasma density
Equinoctial asymmetry of ionospheric vertical plasma drifts and its effect on F‐region plasma density
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DOI：
10.1029/2010ja016081
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发表时间：
2011-02
影响因子：
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通讯作者：
Z. Ren;W. Wan;Libo Liu;Yiding Chen;H. Le
中科院分区：
文献类型：
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作者：
Z. Ren;W. Wan;Libo Liu;Yiding Chen;H. Le
[1]根据1999年至2004年中国卫星1号的观测资料，研究了赤道F区电离层垂直E×B等离子体漂移速度(V⊥)的不对称性。结果发现，观测到的不对称性表现出明显的局部时间依赖性，并具有三个显著的特征。首先，在东半球，0900时至1300时，北半球春分(3-4月)的V-⊥明显高于秋分(9-10月)。第二，V-⊥波数4的纵向结构存在明显的不对称性，几乎全天存在，秋分时甚至延伸到夜间，而春分时主要出现在正午和前夜。第三，在日落前后，预逆增强(PRE)具有明显的不对称性，在320°~150°的经度范围内，秋季的PRE最大速度高于春分，其他经度的PRE则相反。在上述漂移观测的基础上，利用中国科学院地质与地球物理研究所地球电离层理论模型(TIME-IGGCAS)模拟了V-⊥不对称性对电离层等离子体密度的影响。结果表明，白天V-⊥的不对称性可以部分解释刘利伟等人观测到的白天低纬电离层等离子体密度的平分不对称性。(J.地球物理。决议，115，A09307)。
[1] The equinoctial asymmetry of the ionospheric vertical E × B plasma drift velocity (V⊥) in the equatorial F region is investigated based on observations from ROCSAT-1 during 1999 to 2004. It is found that the observed asymmetry exhibits obvious local time dependence with three noticeable features. First, in the Eastern Hemisphere during the interval between 0900 and 1300 LT, V⊥ is obviously higher at the northern spring equinox (March–April) than at the autumn equinox (September–October). Second, there is a pronounced asymmetry for wave number 4 longitudinal structures of V⊥, which exist almost throughout the daytime and even extend into the evening sector at autumn equinox, while they appear mainly at noon and prenoon at spring equinox. Third, around sunset we find an obvious asymmetry of the prereversal enhancement (PRE); the maximum PRE velocity is higher at autumn than at spring equinox in the longitude range from 320° to 150°, and the opposite situation occurs at other longitudes. On the basis of the drift observation mentioned, we also simulate the effect of the V⊥ asymmetry on the ionospheric plasma density by running the Theoretical Ionospheric Model of the Earth, Institute of Geology and Geophysics, Chinese Academy of Sciences (TIME-IGGCAS). It is found that the daytime V⊥ asymmetry can partly explain the equinoctial asymmetry in daytime low-latitude ionospheric plasma density observed by L. Liu et al. (J. Geophys. Res., 115, A09307).