Meteoroid Mass Estimation Based on Single‐Frequency Radar Cross Section Measurements
Meteoroid Mass Estimation Based on Single‐Frequency Radar Cross Section Measurements
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DOI：
10.1029/2021ja029525
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
L. K. Tarnecki;R. Marshall
中科院分区：
文献类型：
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作者：
L. K. Tarnecki;R. Marshall
高功率大口径雷达和较小的流星雷达都可以很容易地观察到流星体烧蚀时产生的致密头部等离子体。然而，根据雷达返回的信息来确定这类流星的质量是具有挑战性的。我们提出了一种从单频雷达测量中提取流星质量的新方法，该方法使用基于物理的等离子体模型和时域有限差分(FDTD)模拟。迪曼特和奥本海姆(2017)得出的头部等离子体模型，https://doi.org/10.1002/2017ja023963取决于流星体的高度、速度和大小。我们使用FDTD模拟雷达脉冲与这种头部等离子体的相互作用，以确定雷达系统对具有给定物理性质的流星的雷达散射截面(RCS)。通过对观测到的参数空间进行模拟，我们建立了流星大小、速度和高度与RCS之间的关系表。然后我们使用这些表格将一组来自MAARSY雷达(53.5 MHz)的观测数据映射到完全定义的等离子体分布，从这些分布中计算出质量。为了验证这些结果，我们使用EISCAT雷达(929 MHz)对相同流星的观测重复了分析。由此产生的质量是强线性相关的；然而，从EISCAT测量得到的质量平均是由MAARSY测量得到的质量的1.33倍。由于这种方法不需要双频测量来进行质量测定，只需要验证，因此它可以在未来应用于许多单频雷达系统的观测。
Both high‐power large aperture radars and smaller meteor radars readily observe the dense head plasma produced as a meteoroid ablates. However, determining the mass of such meteors based on the information returned by the radar is challenging. We present a new method for deriving meteor masses from single‐frequency radar measurements, using a physics‐based plasma model and finite‐difference time‐domain (FDTD) simulations. The head plasma model derived in Dimant and Oppenheim (2017), https://doi.org/10.1002/2017ja023963 depends on the meteoroids altitude, speed, and size. We use FDTD simulations of a radar pulse interacting with such head plasmas to determine the radar cross section (RCS) that a radar system would observe for a meteor with a given set of physical properties. By performing simulations over the observed parameter space, we construct tables relating meteor size, velocity, and altitude to RCS. We then use these tables to map a set of observations from the MAARSY radar (53.5 MHz) to fully defined plasma distributions, from which masses are calculated. To validate these results, we repeat the analysis using observations of the same meteors by the EISCAT radar (929 MHz). The resulting masses are strongly linearly correlated; however, the masses derived from EISCAT measurements are on average 1.33 times larger than those derived from MAARSY measurements. Since this method does not require dual‐frequency measurements for mass determination, only validation, it can be applied in the future to observations made by many single‐frequency radar systems.