Inferred electric field variability in the polarization jet from Millstone Hill E region coherent scatter observations
Inferred electric field variability in the polarization jet from Millstone Hill E region coherent scatter observations
复制标题
根据 Millstone Hill E 区域相干散射观测推断偏振射流的电场变化
DOI：
10.1029/2000rs002531
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发表时间：
2002
期刊：
影响因子：
1.6
通讯作者：
John M. Holt
中科院分区：
文献类型：
--
作者：
P. J. Erickson;John C. Foster;John M. Holt
我们使用Millstone Hill 440 MHz UHF雷达在1998年11月13日的中等扰动期间（Kp = 5）观测到的相干E区后向散射，研究了极化喷流和亚极光离子漂移（SAID）附近亚极光电场的精细尺度结构。我们使用高时间和空间分辨率和雷达响应建模获得的数据的组合，将磁方位角灵敏度和雷达天线波束形状。模型化的雷达响应函数不仅取决于磁场和雷达指向的几何形状，而且还取决于不规则层的高度和范围。除了对雷达系统响应进行建模之外，还使用最佳的正则化反卷积技术来从所使用的相对较长的脉冲长度中解析精细尺度空间结构。在440 MHz的Millstone雷达频率，相干后向散射功率是电场振幅的线性函数，并且我们能够将去卷积功率的范围变化与电场中的空间/时间结构的变化联系起来。我们观察到极化喷流叠加了多个窄（0.1°）强SAID配置电场的实例，其寿命短至1.5分钟，其赤道边缘的梯度高达4 mV/m/km。在我们的实验视野中，DMSP卫星对向西离子漂移的同步观测证实了我们对雷达数据的解释，即跨越3°纬度的亚极光偏振喷流结构以250-400 m/s的速度（交叉L壳层）向极地移动，经过雷达波束，叠加了强烈的SAID电场。
We investigate the fine‐scale structure of the subauroral electric field in the vicinity of the polarization jet and subauroral ion drift (SAID) using coherent E region backscatter observed with the Millstone Hill 440 MHz UHF radar during a moderately disturbed period (Kp = 5) on 13 November 1998. We use a combination of data obtained at high time and spatial resolution and radar response modeling, incorporating magnetic aspect angle sensitivity and radar antenna beam shape. The modeled radar response function depends not only on the magnetic and radar pointing geometry but also on the altitude and extent of the irregularity layer. In addition to modeling of the radar system response, an optimal, regularized deconvolution technique is used to resolve fine‐scale spatial structure from the relatively long pulse length used. At the 440 MHz Millstone radar frequency, coherent backscattered power is a linear function of electric field amplitude, and we are able to relate changes in the range variation of deconvolved power to spatial/temporal structure in the electric field. We observe the polarization jet to have superimposed multiple instances of narrow (0.1°) intense SAID configuration electric fields having lifetimes as short as 1.5 min and gradients on their equatorward edge as large as 4 mV/m per kilometer. Simultaneous DMSP satellite observations of westward ion drift across our experimental field of view confirms our interpretation of the radar data in terms of a subauroral polarization jet structure spanning over 3° latitude moving poleward at 250–400 m/s velocity (cross‐L‐shell) past the radar beam with superimposed intense SAID‐like electric fields.