Midlatitude ionospheric D region: Height, sharpness, and solar zenith angle
Midlatitude ionospheric D region: Height, sharpness, and solar zenith angle
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中纬度电离层 D 区：高度、清晰度和太阳天顶角
DOI：
10.1002/2017ja024455
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
C. Rodger
中科院分区：
文献类型：
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作者：
N. Thomson;M. Clilverd;C. Rodger
甚低频无线电振幅和相位测量被用来确定在~52.5°的中至高地磁倾角纬度处电离层D区的高度和锐度。所使用的两条路径均从德国北部的23.4 kHz发射机DHO开始，第一条路径向北，主要是在沿着丹麦西海岸的海上，范围约为320-425 km，第二条路径也主要是全海，到达苏格兰Eskdalemuir的单个固定记录接收机（约750 km）。根据第一条路径的振幅和相位测量值与距离的关系曲线图，并与美国海军的计算结果进行比较，发现2015年夏季正午D区的等待高度和锐度参数为H′ = 72.8 ± 0.2 km，β = 0.345 ± 0.015 km−1，太阳天顶角约为33°。根据第二条路径上一天中其他时间的相位和振幅测量，确定了从黎明后不久到黄昏前不久H′和β随太阳天顶角的日间变化。比较模态Modektop计算和波跳计算，两者给出了类似的结果。这里发现的参数应该是有用的，在理解能量输入到D区域的辐射带，太阳耀斑，或瞬态发光事件。正午值可能足够精确，可以用于监测气候变化。
VLF radio amplitude and phase measurements are used to find the height and sharpness of the D region of the ionosphere at a mid to high geomagnetic dip latitude of ~52.5°. The two paths used are both from the 23.4 kHz transmitter, DHO, in north Germany with the first path being northward and mainly over the sea along the west coast of Denmark over a range of ~320–425 km, and the second, also mainly all‐sea, to a single fixed recording receiver at Eskdalemuir in Scotland (~750 km). From plots of the measured amplitudes and phases versus distance for the first of these paths compared with calculations using the U.S. Navy code, ModeFinder, the Wait height and sharpness parameters of the D region at midday in summer 2015 are found to be H′ = 72.8 ± 0.2 km and β = 0.345 ± 0.015 km−1 at a solar zenith angle ~33°. From phase and amplitude measurements at other times of day on the second path, the daytime changes in H′ and β as functions of solar zenith angle are determined from shortly after dawn to shortly before dusk. Comparisons are also made between the modal ModeFinder calculations and wave hop calculations, with both giving similar results. The parameters found here should be useful in understanding energy inputs to the D region from the radiation belts, solar flares, or transient luminous events. The midday values may be sufficiently precise to be useful for monitoring climate change.