Modeling the meteor head echo using Arecibo radar observations
Modeling the meteor head echo using Arecibo radar observations
复制标题
使用阿雷西博雷达观测对流星头回波进行建模
DOI：
10.1016/j.jastp.2008.06.016
复制
发表时间：
2008
影响因子：
1.9
通讯作者：
D. Janches
中科院分区：
文献类型：
--
作者：
L. Dyrud;D. Janches
本文报告了通过比较高功率大口径雷达观测的流星头回波信噪比(SNR)和视距多普勒速度，利用一组组合的模型来确定流星体性质的结果。对于这项任务，我们模拟：(1)流星烧蚀和电离过程，(2)流星头-回波雷达截面(RCS)，(3)雷达方程，(4)雷达天线增益方向图，以及估计流星体和观测参数(即方位角、雷达波束内的位置等)的自动最小二乘拟合程序。我们将我们的模拟结果与波多黎各使用阿雷西博430 MHz雷达观测到的236个头部回波事件进行了比较。我们发现，在大范围的头部回波观测中，模拟和观测的SNR与流星高度分布之间有很好的一致性。我们还发现，由这些模型得到的流星体质量分布与使用动力学参数估计的流星体质量分布之间有合理的一致性，动力质量通常导致较低的值约1-2个数量级。我们方法的一个特点是，我们可以追溯流星体在产生观测到的流星所需的大气层(∼150公里高度)上方的原始质量和速度。我们发现，初始质量平均需要比观测时大1-2个数量级，比用动力学方程估计的大3个数量级。这些结果表明，在该粒子的寿命末期观察到了许多流星头回波，这对利用这些观测来确定流星体的性质具有重要意义。自动拟合程序对天线方向图非常敏感，因此可以精确估计流星体在阿雷西博雷达波束内的轨迹位置。结果表明，粒子轨迹到波束中心的距离(即最大增益)与流星体的质量和速度之间存在明显但微弱的依赖关系。这表明，阿雷西博雷达并不像以前的工作中所建议的那样，特别偏向于特定速度的流星体(即高速流星体)。
This paper reports results obtained using a combined set of models to determine meteoroid properties by comparing expected and observed meteor head-echo signal-to-noise ratio (SNR) and line-of-sight Doppler velocity as measured in high-power and large-aperture (HPLA) radar observations. For this task we model: (1) meteor ablation and ionization processes, (2) meteor head-echo radar cross-section (RCS), (3) the radar equation, and (4) the radar antenna gain pattern, together with an automated least-squares fitting procedure to estimate meteoroid and observation parameters (i.e. aspect angle, location within the radar beam, etc.). We compared our simulated results with 236 head-echo events observed using the Arecibo 430MHz radar in Puerto Rico. We found good agreement between modeled and observed SNR versus meteor altitude profiles for a broad range of head-echo observations. We also find reasonable agreement between meteoroid mass distributions resulting from these models and estimated using dynamical arguments, with the dynamical mass generally resulting in lower values by about 1–2 orders of magnitude. A characteristic of our methodology is that we can trace back the original mass and velocity of the meteoroid “above” the atmosphere (∼150km altitude) required to produce the observed meteors. We find that, the original mass is required to be, on average, 1–2 orders of magnitude larger than that at the time of observation, and 3 orders of magnitude larger than estimated using dynamical equations. These results suggest that many meteor head echoes are observed towards the end of the particle's life, which has significant implications for the use of these observations for the determination of meteoroid properties. The automated fitting procedure is very sensitive to the antenna pattern, and therefore allows for precise estimates of the location of the meteoroid's trajectory within the Arecibo radar beam. The results indicate a noticeable, but weak, dependence between the distance of the particle's trajectory from the center of the beam (i.e. maximum gain) and the mass and velocity of the meteoroid. This suggests that the Arecibo radar is not particularly biased toward a specific velocity population of meteoroids (i.e. high velocity) as has been suggested in previous work.