Three-dimensional imaging of atmospheric waves in the thermosphere using network observations over Japan

1)本研究期间分别于2000年7月和2001年10月在日本鹿儿岛Sata和澳大利亚达尔文开始了气辉图像的常规观测。这四个观测站与北海道陆别站（Rikubetsu）和西贺站（Shigaraki）（自1998年10月起）一起继续拍摄气辉图像。在冲绳（1999年8月）和种子岛（2002年8月）进行了战役观察。2000年10月以来，一台法布里-珀罗干涉仪（FPI）在柴荒测量了中间层和热层风。这些常规测量的快速图可在http://stdb2.stelab.nagoya-u.ac.jp/omti/.2上找到)中顶区重力波的结果：a)通过对日本和澳大利亚这些站点的气辉图像进行统计研究，获得了重力波的气候学（发生、传播方向等）。b)在中顶区发现局部（孤立）结构。我们认为非线性波-波相互作用导致了这种结构。更多的重力波和气辉发射是通过使用在两个附近站点获得的气辉图像的三角测量技术确定的。3)中尺度行电离层扰动（MSTID）结果：a)通过对日本气光图像的统计研究，获得了中尺度行电离层扰动的气候学特征（发生、波长、传播方向等）。b)基于卫星数据与FPI模型计算（包括背景风信息）的比较，我们发现mstid不是由重力波直接引起的，而是与电离层不稳定产生的电场结构相对应。c)基于在日本和澳大利亚同时进行的气辉成像观测，我们发现这种电场结构沿着两个半球之间的磁场线传播。4)大尺度旅行电离层扰动（LSTID）结果：确定LSTID为磁暴期间630 nm气辉增强。我们在模式计算和直接风测量的基础上表明，这种LSTID是由热层中的极地风增强（向赤道传播）引起的。我们还从观测到的极光区能量输入出发，论证了简单的极光区风力产生模式并不能解释观测到的LSTID特征。5)基于在日本和澳大利亚同时进行的气辉成像观测，我们发现了两个半球之间对称的等离子体气泡结构。6)研究期间，在日本北部（北海道）成功进行了11次低纬度极光观测。其中两个在日本本土（志荒）观测，记录了日本极光测量的最低纬度。7)利用FPI和MU雷达同时测量的中间层风，估算了气辉发射高度的时间变化。少

1) Routine observation of airglow image has been started since July 2000 at Sata (Kagoshima) and since October 2001 at Darwin (Australia) during this research period. Together with Rikubetsu (Hokkaido) and Shigaraki (Siga) (since October 1998), these four stations continue taking airglow images. Campaign observations were carried out at Okinawa (August, 1999) and Tanegashima (August 2002). A Fabry-Perot interferometer (FPI) measures mesospheric and thermospheric wind since October 2000 at Shigaraki. Quick-look plots of these routine measurements are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/.2) Results for gravity waves in the mesopause region : a) Climatology (occurrence, propagation directions, and so on) of gravity waves were obtained from statistical study of airglow images at these Japanese and Australian stations. b) Localized (isolated) structure was found in the mesopause region. We suggest that nonlinear wave-wave interactions caused this structure. c) Heights of gr … More avity waves and airglow emissions were determined by a triangulation technique using airglow images obtained at two nearby sites.3) Results for medium-scale traveling ionospheric disturbance (MSTID) : a) Climatology (occurrence, wavelength, propagation directions, and so on) of MSTIDs were obtained from statistical study of airglow images in Japan. b) Based on a comparison of satellite data and model calculations including background wind information from FPI, we show that the MSTIDs are not directly caused by gravity waves, but correspond to the electric field structure generated by some ionospheric instability. c) Based on simultaneous airglow imaging observations in Japan and Australia, we found that this electric field structure propagates along magnetic field line between the two hemispheres.4) Results for large-scale traveling ionospheric disturbance (LSTID) : LSTIDs were identified as 630-nm airglow enhancement during magnetic storms. We showed on the basis of model calculations and direct wind measurements that this LSTID was caused by poleward wind enhancement (propagating equatorward) in the thermosphere. We also argued from the observed auroral zone energy input that simple wind generation model in the auroral zone did not explain the observed LSTID features.5) Based on the simultaneous airglow imaging observations in Japan and Australia, we found symmetric plasma bubble structures between the two hemispheres.6) During the research period, we have succeeded observations of low-latitude aurora 11 times in the northern part of Japan (Hokkaido). Two of them were observed in the mainland of Japan (Shigaraki), making a record of lowest latitude of auroral measurement in Japan.7) From simultaneous measurement of mesospheric wind by the FPI and the MU radar, temporal variations of airglow emission height were estimated. Less