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

主要结果总结如下。(i)电离层/热层的季节行为-四年的MU雷达数据进行了分析，以了解季节变化，太阳活动的依赖性，以及电子和离子密度和温度的磁活动行为。在此基础上，导出了热层温度和密度。根据太阳活动和季节的不同，温度始终低于现有模型值2-156 K。(ii)详细研究了F区电子密度的季节性变化。(iii)本文研究了1986年9月至1991年1月期间离子漂移速度MU雷达观测电场的季节性行为，其形式是几种不同季节和太阳活动情况下的日时变化。在MU和阿雷西博雷达位置的最大日振幅和一天中的时间和太阳活动的趋势有很强的相关性。然而，MU数据的季节性趋势， ...更多信息 ibo的数据和现有的雷达模型有很大的不同。目前，热层纬向风正根据这些结果进行研究。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，传播的扰动主要是向赤道方向的，这表明是极光波源，而在平静时期，所有的波方向都被观察到，这表明是当地的低层大气源。(v)1989年10月20日至23日低纬度极光事件期间的电离层结构-在1960年以来日本上空的第一次极光显示期间，在四个倾斜光束中观测到极端的空间和时间梯度。这一观测结果使人们对通常由雷达进行的单基地、顺序三位置、矢量速度测量的有效性产生了怀疑。所有这些结果基本上都是从MU雷达上空进行的“局部”调查。它强烈希望在不久的将来作出进一步努力，扩大这些研究，以考虑与全球强迫机制有关的“非本地”现象。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