An introduction to the Meteor and ionospheric Irregularity Observation System and its preliminary results
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摘要: 流星体注入地球空间给地球带来外部物质并影响地球空间环境. 为了探知流星体对空间环境的影响,需获取不同类型流星体及其在地球大气中产生系列现象的特征. 本文介绍近期研制建设的流星不均匀体多波段探测系统. 该系统设计采用光学大范围成像和无线电相控阵雷达与双基地全天空雷达主动探测,实现对不同尺寸流星体坠入地球高空大气/电离层后的烧蚀、蒸发和电离到流星不均匀体产生与演化等系列过程探测. 通过开发多种探测模式和相应的数据分析反演算法,获取流星体速度、质量、成分和星际来源、流星等离子体头和等离子体尾迹不均匀体的空间精细结构与演化以及低电离层“瞬时”风场等多参量信息. 利用该系统观测数据,对流星体及其产生的流星等离子体头、等离子体尾迹场向和非场向不均匀体、流星闪耀和尘埃不均匀体以及电离层不均匀体等开展了初步研究.Abstract: Meteoroids entering the Earth's atmosphere lose most of their mass during atmospheric passage and considerably disturb the background ionosphere. To elucidate better the effects of meteoroids on the near-Earth space environment, it is important to simultaneously observe various meteoroids and their related phenomena in the Earth's atmosphere. This study briefly describes a newly developed Meteor and ionospheric Irregularity Observation System (MIOS), which consists of a phased-array radar, a bi-static all-sky radar, and a multi-station optical imaging and spectroscopy subsystem. The MIOS can capture the processes of ablation and evaporation of meteoroids, creating luminous and ionization trails, and measure the properties of both the meteor trail and its corresponding meteoroid within a large field of view. Based on the MIOS, some observational modes and data processing methods have been developed, where the physical and chemical properties of meteoroids (including their velocity, mass, composition, and source region), meteor plasma head and trail irregularity and their structural evolution, and the instantaneous neutral wind can be obtained. Using the MIOS measurements, a preliminary study of some of the characteristics of meteoroids, meteor plasma head, meteor plasma trail field–aligned and non-field–aligned irregularities, meteor flare and dust trail irregularity, and ionospheric irregularity is presented.
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Key words:
- meteor /
- meteoroid /
- meteor plasma trail irregularity /
- ionospheric irregularity /
- observation system
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图 2 MIOS相控阵天线阵列不同子阵组合的方向图和全天空阵列方向图,图中叠加的点线短线条代表在电离层E区和F区高度垂直磁力线的方向(更新自 Li G Z et al., 2022)
Figure 2. The radiation pattern of the Meteor and ionospheric Irregularity Observation System (MIOS) phased-array radar under different settings and of the MIOS all-sky radar. The dotted lines in each plot represent the directions perpendicular to the magnetic field at the altitudes of the ionosphere E and F regions (updated from Li G Z et al., 2022)
图 3 MIOS光学子系统在乐东和三亚的观测视场范围,以及在100 km高度的视场重叠区域(更新自Li G Z et al., 2022)
Figure 3. The field of view (FOV) of the Meteor and ionospheric Irregularity Observation System narrow field cameras at Ledong and Sanya and the overlapped area at 100 km altitude (updated from Li G Z et al., 2022)
图 4 一例流星的(a)等离子体头和等离子体尾迹不均匀体回波RTI图和(b)尾迹回波多普勒谱图. 子图(b)中叠加的实线和虚线分别为多普勒速度与谱宽
Figure 4. (a) The range-time-intensity map of the meteor plasma head echo and plasma trail irregularity echo; (b) The Doppler spectrum of the meteor trail echo. The solid and dashed lines in panel (b) are the Doppler velocity and spectral width, respectively
图 5 空间干涉得到的流星尾迹不均匀体的方位与同时的光学轨迹方位的比较. (a)回波RTI图,流星等离子体头和等离子尾迹回波清晰可见;(b)消除模糊度和校正相位偏差后的回波不同通道相位差;(c)利用相位差解算的尾迹不均匀体回波空间位置与光学轨迹空间位置,圆圈表示光学轨迹,点表示不均匀体回波
Figure 5. Comparison of the spatial locations of the meteor plasma trail irregularity echoes obtained by the interferometry analysis and the optical trail. (a) The range-time-intensity map of backscatter echoes, where the meteor plasma head and plasma trail echoes are clearly seen. (b) Phase differences of the echoes between channels 2, 3 and 9, where the phase ambiguity and bias have been removed. (c) Spatial locations of the meteor trail irregularity echoes (dots) calculated using phase differences and of the optical trail (circles)
图 7 MIOS光学子系统观测的一例流星的原始光谱视频合成图像以及提取的光谱曲线. (a)原始光谱观测视频帧合成图像;(b)光谱观测曲线(实线),叠加的虚线为设备响应曲线
Figure 7. Raw spectrum image and the spectrum curve of a meteor recorded by the Meteor and ionospheric Irregularity Observation System's optical subsystem. (a) The observed video composite image of the raw spectrum; (b) The spectral curve derived from the composite image (the solid line). The dashed curve superimposed in panel (b) shows the spectral response of the spectrograph
图 8 2022年双子座流星雨期间观测的镜面流星尾迹以及获取的流星雨流星轨道特征. (a)2022年12月13日20:00—22:00 UT期间观测的镜面流星的空间方位分布,圈和点分别为流星雨流星和偶发流星;(b)流星雨流星的辐射点和轨道参数. V:流星速度;q:轨道近日距;a:轨道半长轴;e:轨道偏心率;i:轨道倾角;node:升交点经度
Figure 8. Specular meteor echoes detected during the Geminid meteor shower in 2022 and the orbital parameters of the Geminids meteors. (a) The distribution of the specular meteors during the period 20:00-22:00 UT; the circles and dots show the Geminid and sporadic meteors, respectively. (b) The radiant and orbital parameters of the Geminids meteors
图 9 流星等离子体头回波在雷达视线方向的减速度(更新自Li G Z et al., 2022)
Figure 9. Deceleration of a meteor plasma head echo in the radar line-of-sight direction (updated from Li G Z et al., 2022)
图 10 流星尾迹不均匀体(非镜面回波)的(a)方位;(b)地方时;(c)高度分布特征,子图(b)中的实线和虚线分别表示镜面和非镜面流星回波的分布,子图(c)中的实线、虚线、点线、点画线分别表示镜面回波的平均高度分布、非镜面回波的起始、结束和平均高度的分布(更新自Wang et al., 2022)
Figure 10. Distribution of the (a) angular location, (b) local time, and (c) height of the meteor trail irregularities (nonspecular meteor echoes). In panel (b), the solid and dashed lines represent the distributions of specular and nonspecular meteor echoes, respectively. In panel (c), the solid, dashed, dotted, and dash-dot lines show the distribution of the mean attitude of specular echoes and the distributions of the beginning, end, and mean altitudes of nonspecular meteor echoes (updated from Wang et al., 2022)
图 11 流星镜面尾迹回波反演的天龙座流星雨流星(a)速度高度分布;(b)辐射点和轨道参数(更新自 Li Y et al., 2022)
Figure 11. (a) Distribution of velocity and altitude; (b) Radiant and orbit parameters of the Draconids meteors obtained from specular meteor echoes (updated from Li Y et al., 2022)
图 12 (a, b)观测的部分流星事例的高度和速度分布特征;(c)流星光谱事例(更新自Yang et al., 2021)
Figure 12. (a, b) Distribution of the altitude and velocity of meteors recorded by the Meteor and ionospheric Irregularity Observation System's optical subsystem during August–September 2019; (c) The spectrum of a meteor (updated from Yang et al., 2021)
图 13 流星(a)光学轨迹;(b)原始光谱;(c)光变曲线;(d)谱线;(e)不均匀体回波RTI图和(f)空间方位分布图(更新自Li et al., 2023)
Figure 13. (a, b) Video composite images of the optical trail and raw spectrum, (c) light curve, (d) spectrum curve, (e) range-time-intensity map of the trail irregularity echo, and (f) angular location in azimuth and elevation of the meteor (updated from Li et al., 2023)
图 14 全天空探测电离层E区不均匀体事例. (a)2020年5月19日12:00—20:00 UT观测的回波RTI图;(b-d)12:34 UT回波的空间方位,及其在东西向-高度平面和东西-南北水平面的投影位置(更新自Sun et al., 2023)
Figure 14. A case of ionospheric E region irregularities detected by the Meteor and ionospheric Irregularity Observation System’s all-sky radar. (a) The range-time-intensity map of backscatter echoes at 12:00–20:00 UT on May 19, 2020; (b–d) The spatial locations of the irregularity echoes at 12:34 UT in the azimuth-elevation, zonal-altitude, and zonal-meridional coordinates, respectively (updated from Sun et al., 2023)
图 15 MIOS相控阵干涉探测电离层全高度不均匀体的空间结构. (a)回波RTI图;(b)回波在东西向-高度平面的位置投影;(c)回波在东西-南北水平面的位置投影
Figure 15. Spatial structure of ionospheric irregularities derived from spatial domain interferometry analysis using the Meteor and ionospheric Irregularity Observation System phased-array radar. (a) The range-time-intensity image of backscatter echoes; (b, c) The spatial locations of ionospheric irregularity echoes in the zonal-altitude and zonal-meridional coordinates
表 1 MIOS无线电子系统基本参数和部分观测实验参数(更新自Li G Z et al., 2022)
Table 1. Parameters of the Meteor and ionospheric Irregularity Observation System's radar subsystem and the experiment configuration used for meteor and ionospheric irregularity observations (updated from Li G Z et al., 2022)
基本参数 全天空雷达(双基地) 相控阵雷达(单基地) 工作频率 38.9 MHz 47.5 MHz 峰值功率 20 kW(发射系统) 72 kW 占空比 10% 10% 波束全宽 360°×140° 1:子阵1-6作为发射,30°×8°;
2:子阵1-2和7-10作为发射,10°×24°增益 4.5 dBi 23.8 dBi 扫描角 固定波束 方位角±48°(无栅瓣) 脉冲波形 方形,高斯 方形,高斯 脉冲编码 互补码,巴克码 互补码,巴克码 天线阵列 6副两单元正交八木天线 135副3单元八木天线 通道数 5个接收通道,1个发射通道 15个接收通道,6个发射通道 流星/电离层 全天空雷达(双基地) 相控阵雷达(单基地) 脉冲重复频率 430 Hz;430 Hz 800 Hz;200 Hz 脉宽 7.2 km;7.2 km 0.8 km;2.5 km 相干积累数,编码 4,互补码;4,互补码 1,单脉冲;2,互补码 距离分辨率 1.8 km;1.8 km 0.8 km;2.5 km -
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