Coordinated radar observations of plasma wave characteristics in the auroral F region
Coordinated radar observations of plasma wave characteristics in the auroral F region
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极光F区等离子体波特征的协调雷达观测
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
W. Bristow
中科院分区：
文献类型：
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作者：
R. Makarevich;W. Bristow
抽象的。利用阿拉斯加地区的科迪亚克高频相干雷达（KOD）和扑克平地非相干散射雷达（PFISR）系统对等离子波特性的协调观测，研究了极光 F 区域十米级等离子波的特性。我们分析了 2012 年 11 月 14 日发生的一个事件，该事件发生在第一次 PFISR 热层离子中性观测 (PINOT) 活动期间，当时 KOD 在 PFISR 监测的广泛位置上收集了分辨率为 1 秒的非常好的 F 区反向散射数据。特别是，两个雷达系统都沿着同一磁子午线连续观测，这使得可以对视线 (l-o-s) 速度数据集进行详细比较。结果表明，时间上（1 秒内）严格匹配的数据点的 l-o-s 速度相关性很大程度上取决于给定后积分间隔内 KOD 检测到的电离层回波数量，或者等效地取决于该间隔内 KOD 回波的发生情况。对于超过 70% 的回波发生率，l-o-s 速度相关性达到 0.7-0.9，而对于低至 10% 的回波发生率，l-o-s 速度相关性也达到 0.5-0.6。使用严格匹配 KOD 和 PFISR 数据点的相同方法，研究了控制相干回波功率的因素，重点关注电场和电子密度依赖性。结果表明，F 区回波的信噪比 (SNR) 随着电场强度的增加以及电子密度的增加而几乎单调增加，除了在大密度值时，SNR 显着下降。电场控制可以理解为在对流快速变化的条件下梯度漂移波的增长速率与对流漂移速度成正比，而密度效应可能涉及大密度值下的过折射以及雷达后向散射功率与扰动密度成正比。
Abstract. Properties of decameter-scale plasma waves in the auroral F region are investigated using coordinated observations of plasma wave characteristics with the Kodiak HF coherent radar (KOD) and Poker Flat Incoherent Scatter Radar (PFISR) systems in the Alaskan sector. We analyze one event on 14 November 2012 that occurred during the first PFISR Ion-Neutral Observations in the Thermosphere (PINOT) campaign when exceptionally good F region backscatter data at 1 s resolution were collected by KOD over the wide range of locations also monitored by PFISR. In particular, both radar systems were observing continuously along the same magnetic meridian, which allowed for a detailed comparison between the line-of-sight (l-o-s) velocity data sets. It is shown that l-o-s velocity correlation for data points strictly matched in time (within 1 s) depends strongly on the number of ionospheric echoes detected by KOD in a given post-integration interval or, equivalently, on the KOD echo occurrence in that interval. The l-o-s velocity correlations reach 0.7–0.9 for echo occurrences exceeding 70%, while also showing considerable correlations of 0.5–0.6 for occurrences as low as 10%. Using the same approach of strictly matching the KOD and PFISR data points, factors controlling coherent echo power are investigated, focusing on the electric field and electron density dependencies. It is demonstrated that the signal-to-noise ratio (SNR) of F region echoes increases nearly monotonically with an increasing electric field strength as well as with an increasing electron density, except at large density values, where SNR drops significantly. The electric field control can be understood in terms of the growth rate of the gradient-drift waves being proportional to the convection drift speed under conditions of fast-changing convection flows, while the density effect may involve over-refraction at large density values and radar backscatter power proportionality to the perturbation density.