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首页> 外文期刊>Annales Geophysicae >Artificial periodic irregularities in the auroral ionosphere
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Artificial periodic irregularities in the auroral ionosphere

机译：极光电离层中的人为周期性不规则现象

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Artificial periodic irregularities (API) areproduced in the ionospheric plasma by a powerful standing electromagnetic wavereflected off the F region. The resulting electron-density irregularities canscatter other high-frequency waves if the Bragg scattering condition is met.Such measurements have been performed at mid-latitudes for two decades and havebeen developed into a useful ionospheric diagnostic technique. We report herethe first measurements from a high-latitude station, using the EISCAT heatingfacility near Troms?, Norway. Both F-region and lower-altitude ionosphericechoes have been obtained, but the bulk of the data has been in the E and Dregions with echoes extending down to 52-km altitude. Examples of API are shown,mainly from the D region, together with simultaneous VHFincoherent-scatter-radar (ISR) data. Vertical velocities derived from the rateof phase change during the irregularity decay are shown and compared withvelocities derived from the ISR. Some of the API-derived velocities in the75–115-km height range appear consistent with vertical neutral winds as shown bytheir magnitudes and by evidence of gravity waves, while other data in the50–70-km range show an unrealistically large bias. For a comparison with ISRdata it has proved difficult to get good quality data sets overlapping in heightand time. The initial comparisons show some agreement, but discrepancies ofseveral metres per second do not yet allow us to conclude that the twotechniques are measuring the same quantity. The irregularity decaytime-constants between about 53 and 70 km are compared with the results of anadvanced ion-chemistry model, and height profiles of recorded signal power arecompared with model estimates in the same altitude range. The calculatedamplitude shows good agreement with the data in that the maximum occurs at aboutthe same height as that of the measured amplitude. The calculated time-constantagrees very well with the data below 60 km but is larger above 60 km by a factorof up to 2 at 64 km. The comparisons with the model are considered to be a goodbasis for more refined comparisons.
机译：在电离层等离子体中，通过反射自F区的强大的固定电磁波会产生人为的周期性不规则（API）。如果满足布拉格散射条件，则由此产生的电子密度不规则性会散射其他高频波。此类测量已在中纬度进行了二十年，并已发展成为一种有用的电离层诊断技术。我们在此报告使用挪威Troms？附近的EISCAT加热设施从高纬度站进行的首次测量。已经获得了F区和低空电离层回波，但是大部分数据都在E和D区，回波一直延伸到52公里的高度。显示了API的示例（主要来自D区域）以及同时的VHF非相干散射雷达（ISR）数据。示出了从不规则衰减期间的相变速率导出的垂直速度，并将其与从ISR导出的速度进行了比较。 API得出的一些在75-115 km高度范围内的速度似乎与垂直中性风一致，如它们的大小和重力波的证据所示，而其他50-70 km范围内的数据则显示出不切实际的大偏差。为了与ISRdata进行比较，事实证明很难获得高度和时间重叠的高质量数据集。最初的比较显示出一些一致性，但是每秒几米的差异还不能使我们得出结论，两种技术正在测量相同的数量。将约53至70 km之间的不规则衰减时间常数与高级离子化学模型的结果进行了比较，并将记录的信号功率的高度轮廓与相同海拔范围内的模型估计值进行了比较。计算出的幅度与数据显示出很好的一致性，因为最大值出现在与测量幅度相同的高度上。计算出的时间常数与60 km以下的数据非常吻合，但在60 km以上的数据在64 km处的系数最大为2。与模型的比较被认为是进行更精细比较的良好基础。

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