Temporal and spatial variations of the equatorial electrojet during storm times from CHAMP observations
Temporal and spatial variations of the equatorial electrojet during storm times from CHAMP observations
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CHAMP 观测中暴风雨期间赤道电急流的时空变化
DOI：
10.1016/j.jastp.2018.07.012
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发表时间：
2018
影响因子：
1.9
通讯作者：
Li Keling
中科院分区：
文献类型：
--
作者：
Zheng Zhichao;Wang Hui;Yu Lei;He Yangfan;Li Keling
在这项研究中，我们研究的时间和空间变化的赤道电急流（EEJ）的特征提取的标量磁场数据从CHAMP卫星在磁暴期间2005年5月15日和8月24日。利用CHAMP观测资料，分析了EEJ扰动的主要物理机制，包括场向电流、大气质量密度、热层纬向风和电离层电子密度。我们发现EEJ在主位相和恢复位相分别有向东和向西的增强。1区FAC在风暴爆发后显著增强，远强于2区，并向中低纬度移动，表明极光区晨昏对流电场可以从高纬度向中低纬度渗透。因此，我们认为瞬发穿透电场是EEJ在主位相期间向东增强的主要原因。有趣的是，EEJ的向西峰值在时间和空间上与大气质量密度扰动从高纬向中低纬的传播相一致，而纬向风在恢复阶段减弱甚至转向东。在本研究中，中低纬向赤道风的增强可能是EEJ向西增强的主要原因，而以往的研究认为，向西纬向风的增强是EEJ向西增强的主要原因。
In this study, we examined the characteristics of temporal and spatial variations of the equatorial electrojet (EEJ) as extracted from the scalar magnetic field data from the CHAMP satellite during magnetic storms on 15 May and 24 August 2005. The main physical mechanisms of EEJ disturbances were analyzed using CHAMP data for the field-aligned currents (FACs), atmospheric mass density, thermospheric zonal winds, and ionospheric electron density. We found that the EEJ had eastward and westward enhancements in the main phase and recovery phase, respectively. The region 1 FACs were significantly strengthened after the storm onset and were much stronger than those in region 2, and they also moved to middle and low latitudes, which indicates that the dawn-to-dusk convection electric field in the auroral zone can penetrate from high latitudes to middle and low latitudes. Therefore, we believed that the prompt penetration electric field was mainly responsible for the eastward enhancement of the EEJ during the main phase. Interestingly, the westward peak of the EEJ coincided in time and space with the propagation of the atmospheric mass density disturbance from high latitudes to middle and low latitudes, whereas the zonal wind weakened and even turned eastward during the recovery phase. In this study, the enhanced equatorward wind at middle and low latitudes can be the main reason for the westward enhancement in the EEJ, whereas previous studies suggested that the enhanced westward zonal wind was responsible for the westward enhancement in the EEJ.