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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。低层热层和中层高层的大气动力学受重力波、潮汐波和行星波等大气波的强烈控制，这些大气波主要从低层向上传播。因此，为了更全面地了解低层热层风动力学，除了研究低层热层风的变化外，研究这些波是如何传播和消散的，以及这些波在低层热层中扮演什么样的角色是至关重要的。基于欧洲非相干散射（EISCAT）雷达和NCAR热层-电离层-中间层-电动力学环流模式，广泛研究了低层风系统的季节和太阳周期变化。例如，夏季在101 km处有强烈的平均东风（约40 m/s），并认为这种特征是由重力波阻力造成的。对EISCAT超高频雷达提供E区中性风资料的三种方法进行了对比研究。从1997年7月14日10时开始，进行了24小时的EISCAT特别节目。对三种方法得到的风速进行了比较，在相对较长的时间变化（几个小时）方面发现了相当好的一致性。对所得速度的比较表明，三静力法在瞬时测量方面优于单静力法，而单静力法在潮汐研究方面具有优势。对于经向风分量，场对准方法在时间覆盖、误差和高度覆盖等方面具有显著优势。我们还探讨了如何利用EISCAT超高频雷达和ME雷达来研究中层和低层热层的耦合过程。风的比较在个案研究和统计基础上进行。在此基础上，我们对高太阳活动条件下高纬度ME雷达获得的91 km以上夏季风数据的使用提出强烈关注。两台雷达观测到的冬季和春分期间的风值是互补的。少