Research on the atmospheric dynamics in the polar raesosphere/thermosphere

极地热层大气动力学研究

基本信息

批准号：
11640441
负责人：
NOZAWA Satonori
金额：
$ 2.18万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640441/
关键词：
lower Thermosphere Mesosphere Polar region neutral wind EISCAT radar MF radar Geomagnetically quiet perkid Total reflection height 中性風地磁気静隠時

项目摘要

We have studied the atmospheric dynamics in the polar mesosphere/lower thermosphere. The atmospheric dynamics in the lower thermosphere and upper mesosphere is strongly controlled by atmospheric waves such as gravity, tidal, and planetary waves which mainly propagate upward from below. To understand the lower thermospheric wind dynamics more fully, therefore, in addition to examining the lower thermospheric wind variations, it is of vital importance to examine how these waves propagate and dissipate and what kind of role these waves play in the lower thermosphere. Seasonal and solar cycle variations of the lower thermospheric wind system were widely examined based on the European Incoherent Scatter (EISCAT) radar as well as NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics general circulation model. It is found that, for example, a strong eastward mean wind (about 40 m/s) in summer maximizing at 101 km, and suggested that this feature in the altitude wind profile is produced by g … More ravity wave drag.We made comparison studies of three methods of the EISCAT UHF radar for furnishing E region neutral wind data. An EISCAT Special Program was conducted for 24 hours starting at 10 UT on July 14, 1997. Derived wind velocities by the three methods are compared, and fairly good agreement is found in terms of a relatively longer temporal variation (a few hours). The comparison of the derived velocities shows that the tristatic method is superior to the monostatic method in terms of an instantaneous measurement, while the monostatic method has an advantage on a tidal study. Regarding the meridional wind component, the filed-aligned method has significant advantages compared to the other methods concerning temporal data coverage, error, and height coverage.We also examined how we can use two radars such as the EISCAT UHF radar and ME radar for study of the coupling process of the mesosphere and lower thermosphere. Comparisons of winds are made in case studies as well as on a statistical basis. Based on the comparisons, we raise strong concerns regarding the use of summer wind data above 91 km obtained by ME radar located at high latitude under high solar activity conditions. The wind values during the winter and equinox observed by the 2 radars are complementary. Less

我们研究了极地中间层/低层热层的大气动力学，以了解低层热层和高层中间层的大气动力学是由重力、潮汐和行星波等主要从下方传播的大气波控制的。因此，除了研究低热层风的变化之外，研究这些波如何传播和消散以及这些波在低热层中发挥什么样的作用也至关重要。基于欧洲非相干散射（EISCAT）雷达以及 NCAR 热层-电离层-中层-电动力学大气环流模型，对低热层风系统的季节和太阳周期变化进行了广泛的研究，发现例如有较强的东向风。夏季平均风速（约40 m/s）在101 km处达到最大值，并认为高空风廓线的这一特征是由重力波阻力产生的。我们进行了对比研究EISCAT UHF 雷达提供 E 区中性风数据的三种方法的比较 EISCAT 特别计划于 1997 年 7 月 14 日 10 UT 开始进行了 24 小时。比较了三种方法得出的风速，结果吻合良好。发现在相对较长的时间变化（几个小时）方面，得出的速度的比较表明，三基地法在瞬时测量方面优于单基地法，虽然单基地方法在潮汐研究方面具有优势，但与其他方法相比，场对准方法在时间数据覆盖范围、误差和高度覆盖范围方面具有显着优势。我们还研究了如何使用两种方法。 EISCAT UHF 雷达和 ME 雷达等用于研究中间层和低层热层耦合过程的雷达在案例研究和统计基础上进行了比较，我们对风的研究提出了强烈的关注。利用位于高纬度地区高太阳活动条件下的ME雷达获得的夏季风数据，2台雷达观测到的冬季和春分时的风值互补性较小。