Ionospheric Response to the 21 May 2012 Annular Solar Eclipse Over Taiwan
Ionospheric Response to the 21 May 2012 Annular Solar Eclipse Over Taiwan
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DOI：
10.1029/2018ja025928
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
J. Liu;S. S. Yang-S.;P. Rajesh;Y. Sun;J. Chum;C. Pan;Y. Chu;C. Chao;L. Chang
中科院分区：
文献类型：
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作者：
J. Liu;S. S. Yang-S.;P. Rajesh;Y. Sun;J. Chum;C. Pan;Y. Chu;C. Chao;L. Chang
2012年5月21日清晨，一场日环食横扫台湾。这为研究电离层对日食的响应提供了一个极好的机会，主要是由于光化学效应。当地的地面全球定位系统接收器、电离层探测仪、高频连续波多普勒探测系统和甚低频接收器被用来观测电离层日食特征。这些多仪器观测表明，极端的总电子含量（TEC）下降滞后于最大遮蔽约5-20分钟，而多普勒频移减少和增加（即，电离层上升和下降）。电离层资料与TEC和多普勒频移观测结果吻合较好。结果表明，极端TEC下降滞后（即，延迟时间）与相关的最大遮蔽度成反比，证实了2012年5月21日环食期间台湾的光化学过程是必不可少的。本文首次提出了一个解释日食光化学延迟时间的理论推导。
An annular solar eclipse swept over Taiwan in the early morning on 21 May 2012. This provides an excellent opportunity to study ionospheric response to the solar eclipse mainly due to photochemical effects. Local ground‐based Global Positioning System receivers, an ionosonde, high frequency‐continue wave Doppler sounding systems, and very low frequency receivers are used to observe ionospheric eclipse signatures. These multiinstrument observations show that the extreme total electron content (TEC) depression lags the maximum obscuration by about 5–20 min, while the Doppler frequency shift decreases and increases (i.e., the ionosphere ascends and descends) during first contact‐maximum obscuration and maximum obscuration‐last contact, respectively. The ionosonde data well agree with the TEC and Doppler frequency shift observations. The results show that the extreme TEC depression lag (i.e., delay time) being inversely proportional to the associated maximum obscuration confirms that the photochemical process is essential in Taiwan during the 21 May 2012 annular solar eclipse. A theoretical derivation is proposed for the first time to explain the delay time due to pure photochemical process during solar eclipses.