Temporal and Spatial Variability of the Mid-latitude Ionosphere and Thermosphere

主要研究结果总结如下。(I)电离层/热层的季节行为--分析了四年的MU雷达数据，以了解电子和离子密度和温度的季节变化、太阳活动相关性以及磁活动行为。根据这些数据，得出了热层的温度和密度。根据太阳活动和季节的不同，温度一直比现有的模型值低2-156K。(2)详细研究了F区电子密度的季节变化规律。(3)离子漂移速度的季节行为--对1986年9月至1991年1月期间的电场的MU雷达观测，以几种不同的季节和太阳活动情况的时间变化的形式进行了研究。MU和阿雷西博雷达位置的最大日振幅以及一天中的时间和太阳活动趋势有很大的相似之处。然而，MU数据中的季节性趋势，AREC…更多的IBO数据，与现有的雷达模型强烈不同。目前，正在根据这些结果调查热层经向风。(4)中纬度电离层扰动--分析了500多小时的多波束雷达观测。在磁扰动时期，行进扰动主要向赤道方向移动，表明是极光波源，而在平静时期，观测到所有波的方向，表明是局部低大气震源。(5)1989年10月20日至23日低纬极光事件期间的电离层结构--自1960年以来首次在日本上空进行极光显示时，观测到四个倾斜波束的极端空间和时间梯度。这一观察结果使雷达经常进行的单站、顺序三位置矢量测速的有效性受到质疑。所有这些结果本质上都是MU雷达的“局部”调查开销。它强烈希望在不久的将来作出进一步努力，扩大这些研究，以审议与全球强迫机制有关的“非本地”现象。较少

The principal results are summarized as follows. (i) Ionospheric/thermospheric seasonal behavior-four years of MU radar data are analyzed to understand the seasonal variations, solar activity dependence, and magnetic activity behavior of the electron and ion density and temperature. Based on these data, the thermospheric temperatures and densities are derived. The temperatures are consistently lower than existing model values by 2-156 K,depending upon solar activity and season. (ii) The seasonal behavior of F-region electron density is investigated in detail. (iii) Seasonal behavior of ion-drift velocities-MU radar observations of electric fields during September 1986 to January 1991 are investigated in the form of time-of-day variations for several different seasonal and solar-activity cases. The maximum daily amplitudes and the time-of-day and solar activity trends at the MU and the Arecibo radar locations have strong resemblances. However the seasonal trends in the MU data, the Arec … More ibo data, and existing radar models disagree strongly. Currently, the thermospheric meridional winds are being investigated from these results. (iv)Mid-latitude ionospheric disturbances-over 500 hours of multiple-beam radar observations are analyzed. During magnetically disturbed times the traveling disturbances are very predominantly equatorward, indicating an auroral wave source, while during quiet times all wave directions are observed, indicating a local, lower-atmosphere source. (v) Ionospheric structure during the low-latitude auroral event of 20-23 October 1989-during the first auroral display over Japan since 1960, extreme spatial and temporal gradients are observed in four oblique beams. This observation calls into doubt the validity of the monostatic, sequential-three-position, vector velocity measurement often made by radars.All of these results are essentially "local" investigations overhead from the MU radar. It strongly hoped that further efforts will be made in the near future to expand these studies to consider "non-local" phenomena related to global forcing mechanisms. Less