On the sheet‐like nature of 150 km (F1) radar echoes
On the sheet‐like nature of 150 km (F1) radar echoes
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关于 150 公里 (F1) 雷达回波的片状性质
DOI：
10.1029/2007gl032152
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发表时间：
2008
影响因子：
5.2
通讯作者：
W. Ecklund
中科院分区：
文献类型：
--
作者：
R. Tsunoda;W. Ecklund
所谓的150 km（或F1）回波被证明是由嵌入片状区域的场向不规则性（FAI）引起的。使用圣诞岛上的49.92 MHz雷达，其天线波束以29.5°的天顶角指向地理东方，雷达散射体积内的高分辨率多普勒速度变化被用于推断片状区域可能具有倾斜和曲率。这一发现被用来推断等离子体密度（N）必须在片状区域内增强，并且FAI可能是由交换不稳定性产生的，由垂直电场或作用于N梯度水平分量的纬向中性风驱动。讨论了如何在F1区域形成倾斜的片状结构。
The so‐called 150 km (or F1) echoes are shown to arise from field‐aligned irregularities (FAI) that are embedded in a sheet‐like region. Using a 49.92 MHz radar on Christmas Island, which has an antenna beam directed toward geographic east at a zenith angle of 29.5°, high‐resolution Doppler‐velocity variations within the radar scattering volume are used to infer that the sheet‐like region could have both tilt and curvature. This finding is used to infer that plasma density (N) must be enhanced within the sheet‐like region, and that FAI could be generated by an interchange instability, driven by a vertical electric field or a zonal neutral wind that acts on the horizontal component of the gradient in N. How tilted sheet‐like structures could form in the F1 region is discussed.