An overturning-like thermospheric Na layer and its relevance to Ionospheric field aligned irregularity and sporadic E
An overturning-like thermospheric Na layer and its relevance to Ionospheric field aligned irregularity and sporadic E
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DOI：
10.1016/j.jastp.2016.12.006
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发表时间：
2017-09
影响因子：
1.9
通讯作者：
X. Xue;Guozhu Li;X. Dou;X. Yue;Guotao Yang;Jinsong Chen;Tingdi Chen;B. Ning;Jihong Wang
中科院分区：
文献类型：
--
作者：
X. Xue;Guozhu Li;X. Dou;X. Yue;Guotao Yang;Jinsong Chen;Tingdi Chen;B. Ning;Jihong Wang
利用海口钠激光雷达于2012年7月29日观测到的热层钠层（TSL）在100-120 km高度区域内的一个翻转状结构。在14：55 ~ 15：50 UT，钠层从钠层顶部（约102 km）上升到约118 km高度，然后以3.5 km/h的速度逐渐下降。COSMIC无线电掩星和三个电离层探测仪的观测结果表明，海口地区的无线电掩星信噪比剖面和电离图中的Es分布分别呈现出突变扰动，表明海口地区存在复杂的Es。另一方面，三亚（18.4°N，距海口220 km）和福科（19.5°N，距海口130 km）的甚高频雷达都记录到了E区强的场向不规则（FAI）回波高度延伸结构，覆盖高度为100-140 km，这与热层钠层的翻转状结构有很好的对应关系。钠层（和FAI）结构的出现时间和复杂的Es之间的良好的协议可以表明它们之间的密切相关性。一种可能性是，在络合物Es（具有高度变形结构）过程中的化学反应可以产生足够的钠原子，从而导致钠层上涌结构的形成。相应地，FAI高度扩展结构可以通过高度扩展（变形）Es中的梯度漂移不稳定性产生，该不稳定性提供等离子体密度梯度以支持不稳定性的发展。
We report an overturning-like structure of the thermospheric sodium layer (TSL) in the altitude region of ∼100–120 km observed by a sodium lidar at Haikou (20.0°N), China, on July 29, 2012. The overturning-like sodium layer was first seen as upwelling from the top of the sodium layer (∼102 km) to an altitude of ∼118 km from 14:55 to 15:50 UT and then descending gradually from its apex with a speed of 3.5 km/h. The ionospheric observations from the COSMIC radio occultation and three ionosondes exhibited abrupt perturbations in the radio occultation (RO) SNR profiles and spread Es in the ionograms, respectively, indicating the existence of complex Es around Haikou. On the other hand, VHF radars located at Sanya (18.4°N, 220 km away from Haikou) and Fuke (19.5°N, 130 km away from Haikou) both recorded strong E region field-aligned irregularity (FAI) echoes altitude-extended structure covering altitudes of 100–140 km, which are well correlated with the overturning-like structure of the thermospheric sodium layer. The good agreement between occurrence time of sodium layer (and FAI) structure and of complex Es could indicate a close correlation between them. One possibility is that the chemical reaction in the course of the complex Es (with altitude-deformed structure) could produce sufficient sodium atoms and thus lead to the formation of sodium layer upwelling structure. Correspondingly, FAI altitude-extended structure could be generated through the gradient drift instability in the altitude-extend (deformed) Es which provide plasma density gradients to support the instability development.