MF radar observations of meteors and meteor-derived winds at Syowa (69°S, 39°E), Antarctica: A comparison with simultaneous spaced antenna winds
MF radar observations of meteors and meteor-derived winds at Syowa (69°S, 39°E), Antarctica: A comparison with simultaneous spaced antenna winds
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DOI：
10.1029/2005jd005849
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发表时间：
2005-12
影响因子：
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通讯作者：
M. Tsutsumi;T. Aso
中科院分区：
文献类型：
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作者：
M. Tsutsumi;T. Aso
文[1]给出了南极西奥瓦中频雷达(69°S，39°E)对流星的首次长期观测结果。在冬季，流星风的测量可以全天进行，不会受到群体延迟或全反射的严重影响，而在夏天，观测范围限制在当地时间0000左右的几个小时内。每天的流星回声速率(大约300-1000)与当地的K指数有明显的反相关关系，表明观测大多代表了地磁平静的条件。回波分布在80公里到120公里左右，峰值高度在100公里左右。最大高度由采用的相对较慢的采样频率(5赫兹)设置，并有望通过使用较高的频率来扩展。比较了流星风和全相关分析(FCA)冬季风的异同。它们在大约90公里处吻合得很好，而FCA风往往低估了高空的流星风。一个值得注意的发现是，风速的方向也可能不同。FCA风在90公里以上的高度变化较小，FCA高度似乎被高估了。一项从中频回波估计的到达角的案例研究表明，流星回波有可能污染电离层回波，低至80公里。然而，对流星污染对FCA风速的影响(如果有的话)的定量评估尚未完成，仍是一个有待研究的课题。还应寻求导致差异的其他来源。目前同时使用FCA和流星技术的MF雷达观测的高度覆盖范围非常广(从大约60公里到近120公里)，这将对极地中间层和低热层的研究做出重大贡献。
[1] The first results of long-term meteor observations made with Syowa MF radar (69°S, 39°E), Antarctica, are presented. In winter, meteor wind measurements can be conducted throughout the day without being severely affected by group retardation or total reflection, while in summer the observations are confined within several hours around 0000 local time (LT). Daily meteor echo rates (roughly 300–1000) are clearly anticorrelated with local K indices, indicating that the observations mostly represent geomagnetically quiet conditions. Echoes are distributed from around 80 km to 120 km, with the peak altitude at around 100 km. The maximum height is set by the relatively slow sampling frequency employed (5 Hz) and is expected to be extended by using a higher frequency. Meteor and full correlation analysis (FCA) winds in winter months are compared. They agree well at around 90 km, while the FCA winds tend to underestimate the meteor winds at upper altitudes. A notable finding is that the directions of wind velocities can also be different. The FCA winds show less height variations above about 90 km and it appears as though the FCA heights are overestimated. A case study of angles of arrival estimated from MF echoes suggests a possibility that meteor echoes contaminate ionospheric echoes down to as low as 80 km. However, quantitative evaluation of meteor contamination effects, if any, on FCA wind velocities has not been done yet and remains a future topic to be studied. Other sources which cause the differences should also be sought. The remarkably wide height coverage of the present MF radar observations (from around 60 to nearly 120 km) using both FCA and meteor techniques simultaneously will greatly contribute to polar mesosphere and lower thermosphere study.