Influence of meteors on the mesosphere studied by the cooperative radar/lidar

雷达/激光雷达协同研究流星对中间层的影响

基本信息

批准号：
08454137
负责人：
TSUDA Toshitaka
金额：
$ 4.86万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454137/
关键词：
Mesopause Meteor Meteor Radar Sodium Lidar Airglow Middle and Upper Atmosphere Metallic Atom Layer Sporadic Sodium Layer 大気発光層ナトリウム層リモートセンシング中層大気

项目摘要

In this study, meteor trails have been observed by the MU radar of Kyoto University, in order to investigate meteor flux and mesospheric dynamical parameters. Simultaneous lidar and airglow imager observations have been carried out and results are compared, in order to clarify the mechanism of variations of constituents in the mesosphere and mesopause region. Especially, sporadic sodium layer is focused as one of the main targets. From plenty of simultaneous observations, the following findings have been revealed.1. The meteor flux was not influenced by the major meteor stream activity, from the MU radar observation with a high sensitivity. However, if height, direction, or meteor echo strength is limited there could be a significant temporal variation.2. The temporal variation of sodium density around the mesopause with slow downward progression with a period larger than several hours was confirmed to be inertia gravity waves.3. The sporadic sodium layer was sometimes accompanied by localized temperature increase or wind shear. Especially, there was a strong correlation between the vertical shear of horizontal wind and occurrence of sporadic sodium layers. No significant correlation was found between the meteor flux and sporadic sodium layer.4. During the cooperative observation of sodium lidar and airglow imager, atmospheric gravity events were frequently observed in the airglow layer by the imagers, which have clarified climatologies and structures of small scale gravity waves in the mesopause region.5. Strong activity of bright Leonid meteors (fireballs) were observed by the MU radar about one day prior to the predicted meteor storm in November 1998. However, no significant influence on the mesopause region was found by the optical measurement.

本研究利用京都大学的MU雷达观测流星轨迹，以研究流星通量和中层动力学参数。为了阐明中间层和中间层顶区域成分的变化机制，进行了激光雷达和气辉成像仪的同步观测并比较了结果。特别是，零星的钠层作为主要目标之一受到关注。通过大量同时观察，得出以下结论： 1．从高灵敏度的MU雷达观测来看，流星通量不受主要流星流活动的影响。然而，如果高度、方向或流星回波强度有限，则可能会出现显着的时间变化。2．中层顶周围钠密度的时间变化缓慢下降，周期大于几个小时，被证实为惯性重力波。 3．零星的钠层有时伴随着局部温度升高或风切变。特别是水平风的垂直切变与零星钠层的出现有很强的相关性。流星通量与零星钠层之间没有发现显着的相关性。4．在钠激光雷达和气辉成像仪的联合观测过程中，成像仪在气辉层频繁观测到大气重力事件，阐明了中层顶区域小尺度重力波的气候特征和结构。5． 1998年11月预测的流星风暴前一天，MU雷达观测到明亮的狮子座流星（火球）的强烈活动。然而，光学测量没有发现对中层顶区域有显着影响。