Observations of meteor-head echoes using the Jicamarca 50 MHz radar in interferometer mode
Observations of meteor-head echoes using the Jicamarca 50 MHz radar in interferometer mode
复制标题
使用 Jicamarca 50 MHz 雷达在干涉仪模式下观测流星头回波
DOI：
10.5194/acp-4-511-2004
复制
发表时间：
2003
影响因子：
6.3
通讯作者：
R. Woodman
中科院分区：
文献类型：
--
作者：
J. Chau;R. Woodman
抽象的。本文介绍了用高功率大口径Jicamara 50 MHz雷达(11.95°S，76.87°W)在干涉模式下对流星头回波的最新观测结果。该系统的大功率孔径使我们能够在1°天线波束覆盖的小体积内每小时记录超过3000颗流星，尽管在杂波的赤道电喷流(EEJ)回波不存在或非常弱的情况下。干涉测量装置可以确定每颗流星的辐射量(轨迹)和速度。结果发现，在迄今观测到的所有季节中，所有探测到的流星的辐射分布都集中在相对较小的角度上，当它经过Jicamara天空时，以地球顶点为中心，即围绕相应的地球运行特定的观测日期和时间。在地球惯性参照系中，沿黄道面横轴方向的色散约为18°，在黄道面的日心经度方向仅为8.5°。没有观察到明显的年际变化。此外，没有发现与1998-2002年的光学(较大的流星)狮子座流星雨有关的种群，这与其他大功率口径雷达的观测结果一致。一种新的互相关检测技术(自适应匹配滤波)与13波特Barker相位码相结合。与其他雷达使用的非编码长脉冲方案相比，该技术使我们能够在相同的平均功率下获得良好的距离分辨率(0.75公里)而不会有任何灵敏度下降。匹配的多普勒频移提供对脉冲内速度的估计，其精度与使用相同长度的非编码脉冲的精度相同。流星的速度分布较窄，中心在60公里-1左右。因此，大多数流星围绕太阳的逆行轨道几乎是圆形的。只有不到8%的速度对应于星际轨道，即速度大于太阳逃逸速度(72公里-1)。还给出了感兴趣的其他统计分布。
Abstract. We present results of recent observations of meteor-head echoes obtained with the high-power large-aperture Jicamarca 50MHz radar (11.95°S, 76.87°W) in an interferometric mode. The large power-aperture of the system allows us to record more than 3000 meteors per hour in the small volume subtended by the 1° antenna beam, albeit when the cluttering equatorial electrojet (EEJ) echoes are not present or are very weak. The interferometry arrangement allows the determination of the radiant (trajectory) and speed of each meteor. It is found that the radiant distribution of all detected meteors is concentrated in relative small angles centered around the Earth's Apex as it transits over the Jicamarca sky, i.e. around the corresponding Earth heading for the particular observational day and time, for all seasons observed so far. The dispersion around the Apex is ~18° in a direction transverse to the Ecliptic plane and only 8.5° in heliocentric longitude in the Ecliptic plane both in the Earth inertial frame of reference. No appreciable interannual variability has been observed. Moreover, no population related to the optical (larger meteors) Leonid showers of 1998-2002 is found, in agreement with other large power-aperture radar observations. A novel cross-correlation detection technique (adaptive match-filtering) is used in combination with a 13 baud Barker phase-code. The technique allows us to get good range resolution (0.75km) without any sensitivity deterioration for the same average power, compared to the non-coded long pulse scheme used at other radars. The matching Doppler shift provides an estimation of the velocity within a pulse with the same accuracy as if a non-coded pulse of the same length had been used. The velocity distribution of the meteors is relatively narrow and centered around 60kms -1 . Therefore most of the meteors have an almost circular retrograde orbit around the Sun. Less than 8% of the velocities correspond to interstellar orbits, i.e. with velocities larger than the solar escape velocity (72kms -1 ). Other statistical distributions of interest are also presented.