Determination of meteoroid physical properties from tristatic radar observations
Determination of meteoroid physical properties from tristatic radar observations
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根据三基地雷达观测确定流星体物理特性
DOI：
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发表时间：
2008
期刊：
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通讯作者：
D. Meisel
中科院分区：
文献类型：
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作者：
J. Kero;C. Szasz;A. Pellinen‐Wannberg;G. Wannberg;A. Westman;D. Meisel
在这项工作中，我们给出了一个审查的流星头回波观测进行了三基地930 MHz EISCAT超高频雷达系统在2002年和2005年之间的四个24小时的运行，并与早期的观测比较。总共观测到410颗三站流星。我们描述了一种方法来确定一个紧凑的雷达目标的位置，在共同的体积监测的三个接收机，并证明其适用于流星研究。流星目标的推断位置已被用来估计它们的速度，减速和方向的到来，以及它们的雷达散射截面与前所未有的精度。类星体的速度分布为双峰型，峰值在35-40 km/s和55-60 km/s，范围在19-70 km/s。估计质量在109 ~ 105.5kg之间。在30 km/s以下的探测很少。观测结果明显偏向于高速流星体，但不像以前的三站测量所假定的那样偏向于慢速流星体。最后，我们讨论了用单基地雷达观测到的径向减速度如何依赖于流星体的速度和轨道与波束之间的角度。如果将接近雷达的流星体的径向速度和减速度用作动量运动方程中真实量的估计，则有限波束宽度会导致低估流星体质量。大气层高度约70-140公里。回波的特点是瞬态和多普勒频移。接收到的能量被限制在一定的范围内，如从一个点源，目标以流星体的视线速度移动。
In this work we give a review of the meteor head echo observations carried out with the tristatic 930 MHz EISCAT UHF radar system during four 24 h runs between 2002 and 2005 and compare these with earlier observations. A total number of 410 tristatic meteors were observed. We describe a method to determine the position of a compact radar target in the common volume monitored by the three receivers and demonstrate its applicability for meteor stud- ies. The inferred positions of the meteor targets have been utilized to estimate their velocities, decelerations and direc- tions of arrival as well as their radar cross sections with un- precedented accuracy. The velocity distribution of the mete- oroids is bimodal with peaks at 35-40 km/s and 55-60 km/s, and ranges from 19-70 km/s. The estimated masses are be- tween 10 9 -10 5.5 kg. There are very few detections below 30 km/s. The observations are clearly biased to high-velocity meteoroids, but not so biased against slow meteoroids as has been presumed from previous tristatic measurements. Fi- nally, we discuss how the radial deceleration observed with a monostatic radar depends on the meteoroid velocity and the angle between the trajectory and the beam. The finite beamwidth leads to underestimated meteoroid masses if ra- dial velocity and deceleration of meteoroids approaching the radar are used as estimates of the true quantities in a momen- tum equation of motion. atmosphere at about 70-140 km altitude. The echoes are characterized by being transient and Doppler shifted. The received power is confined in range, as from a point source, and the target moves with the line-of-sight velocity of the meteoroid.