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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Response of the equatorial lower ionosphere to the total solar eclipse of 22 July 2009 during sunrise transition period studied using VLF signal
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Response of the equatorial lower ionosphere to the total solar eclipse of 22 July 2009 during sunrise transition period studied using VLF signal

机译：利用甚低频信号研究了2009年7月22日赤道电离层对日全食的响应

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摘要

Changes in equatorial D-region electron density are studied using subionospherically propagating VLF signal at 18.2 kHz over a distance of 2200 km during the total solar eclipse of 22 July 2009. There are very few studies about the eclipse's effects on the equatorial lower ionosphere in the scientific literature. In the light of that, the objective of the present work is to study the effects of the eclipse on the dynamics of the equatorial lower ionosphere during ionospheric sunrise transition period. In the present case, great circle path between VLF transmitter and receiver falls totally in partial eclipse zone, having a maximum solar obscuration of 90% and an average obscuration of 74%. Results show an average decrease of 3.2 dB in signal strength compared to control days during peak solar obscuration over the path. A comparison with previous studies shows an increase both in lower ionosphere virtual reflection height (H') and Wait inverse scale height parameter (β); the values estimated are 74.5 km and 0.46 km~(-1) compared to unperturbed ionosphere values of 71 km and 0.43 km~(-1), respectively. During maximum eclipse over the path, the model profile shows an average 80% drop in electron density at a height of 71 km at equatorial lower ionosphere. A nonlinear variation of lower ionosphere electron density with solar radiation is found as opposed to the model study proposed by previous workers.
机译：在2009年7月22日的日全食期间，使用了在2200 km距离上以18.2 kHz的亚电离层传播VLF信号，研究了赤道​​D区电子密度的变化。关于日食对赤道下层电离层影响的研究很少。科学文献。有鉴于此，本研究的目的是研究日食对电离层日出过渡期赤道下层电离层动力学的影响。在当前情况下，VLF发射器和接收器之间的大环形路径完全落在部分月食区，最大太阳遮盖度为90％，平均遮挡度为74％。结果表明，与日照相比，在该路径上的峰值日照模糊时，信号强度与对照组相比平均降低了3.2 dB。与先前研究的比较表明，较低的电离层虚拟反射高度（H'）和等待反比例高度参数（β）均增加;与无扰动电离层值分别为71 km和0.43 km〜（-1）相比，估计值分别为74.5 km和0.46 km〜（-1）。在路径上的最大月食期间，模型剖面显示，在赤道电离层高度71 km处，电子密度平均下降了80％。发现较低电离层电子密度随太阳辐射的非线性变化，这与先前工作人员提出的模型研究相反。

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