Lightning whistler waves in the high‐latitude magnetosphere
Lightning whistler waves in the high‐latitude magnetosphere
复制标题
高纬度磁层中的闪电哨声波
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
M. Kelley
中科院分区：
文献类型：
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作者：
R. Holzworth;R. Winglee;B. H. Barnum;Yaqi Li;M. Kelley
众所周知，由闪电引起的惠斯勒波会以显着的波幅穿透电离层。最近的火箭实验表明，距离电离层火箭子轨道 1000 公里处的闪电很容易被看到。电离层中闪电的频谱能量密度通常在接近或低于 1 kHz 的频率下具有显着的功率。如果这种低频哨声波从尖点或极冠开始，它们可以一路传播到磁层顶边界层。夏季，闪电在高纬度大陆块上很常见，这使得波源功能很好地位于尖端和极冠的范围内。使用全局三维二维流体代码进行射线追踪研究，以研究这些哨声波在高纬度磁层中的传播。将估计的映射闪电哨声波振幅与 ISEE 和 AMPTE 的波强度测量值进行比较，并支持 Geotail 在白天磁层顶附近看到的降调哨声波可能来自强烈闪电的论点。研究发现，绘制的闪电哨声波振幅与在外阳侧磁层和低纬度边界层测量的现场波振幅相当。
Whistler waves caused by lightning are known to penetrate the ionosphere with significant wave amplitudes. Recent rocket experiments have shown that lightning from sources as far as 1000 km from the ionospheric rocket subtrack are easily seen. The spectral energy density of lightning in the ionosphere often has significant power at frequencies near and below 1 kHz. Such low-frequency whistler waves can propagate all the way to the magnetopause boundary layer if they begin in the cusp or polar cap. Lightning is common over high-latitude continental land masses in the summer months which places this wave source function well within range of the cusp and polar cap. Ray tracing studies using a global three-dimensional two-fluid code are conducted to investigate the propagation of these whistler waves into the high latitude magnetosphere. The estimated, mapped lightning whistler wave amplitude is compared to wave intensity measurements from ISEE and AMPTE and supports the argument that falling tone whistler waves, seen by Geotail near the dayside magnetopause, may have been from intense lightning. It is found that the mapped whistler wave amplitude from lightning is comparable to the in situ wave amplitudes measured in the outer dayside magnetosphere and low latitude boundary layer.