Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear
Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear
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DOI：
10.5194/angeo-37-273-2019
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发表时间：
2018-11
影响因子：
1.9
通讯作者：
C. Jacobi;C. Arras;Christoph Geißler;F. Lilienthal
中科院分区：
文献类型：
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作者：
C. Jacobi;C. Arras;Christoph Geißler;F. Lilienthal
抽象的。 GPS 无线电掩星 (RO) 技术用于利用 COSMIC/FORMOSAT-3 卫星的 GPS 信噪比 (SNR) 剖面来研究全球范围内地球电离层的零星 E (Es) 层等离子体不规则性。与平均 SNR 的最大偏差可归因于 Es 层的高度。人们普遍认为，Es是在地球磁场水平分量存在的情况下，由于垂直风切变而由离子会聚产生的，而风切变主要由太阳潮汐提供。在这里，我们对 Es 发生率中的季度潮汐 (QDT) 特征进行了分析。通过与Collm（51.3∘N，13.0∘E）流星雷达获得的中层/低层热层风切变的局部比较，我们发现Es中QDT的相位与除夏季外所有季节的纬向风负垂直切变的相位都非常吻合，此时QDT幅度较小。我们还将全局 QDT Es 信号与数值模型结果进行了比较。 Es 发生率的全球分布在质量上与模拟的纬向风切变一致。结果表明，纬向风切变确实是Es中QDT的重要驱动机制。
Abstract. The GPS radio occultation (RO) technique is used to study sporadic E (Es) layer plasma irregularities of the Earth's ionosphere on a global scale using GPS signal-to-noise ratio (SNR) profiles from the COSMIC/FORMOSAT-3 satellite. The maximum deviation from the mean SNR can be attributed to the height of the Es layer. Es are generally accepted to be produced by ion convergence due to vertical wind shear in the presence of a horizontal component of the Earth's magnetic field, while the wind shear is provided mainly by the solar tides. Here we present analyses of quarterdiurnal tide (QDT) signatures in Es occurrence rates. From a local comparison with mesosphere/lower thermosphere wind shear obtained with a meteor radar at Collm (51.3∘ N, 13.0∘ E), we find that the phases of the QDT in Es agree well with those of negative vertical shear of the zonal wind for all seasons except for summer, when the QDT amplitudes are small. We also compare the global QDT Es signal with numerical model results. The global distribution of the Es occurrence rates qualitatively agrees with the modeled zonal wind shears. The results indicate that zonal wind shear is indeed an important driving mechanism for the QDT seen in Es.