First observations of the midlatitude evening anomaly using Super Dual Auroral Radar Network (SuperDARN) radars
First observations of the midlatitude evening anomaly using Super Dual Auroral Radar Network (SuperDARN) radars
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使用超级双极光雷达网络（SuperDARN）雷达首次观测到中纬度夜间异常
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
M. Lester
中科院分区：
文献类型：
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作者：
S. D. Larquier;J. Ruohoniemi;J. Baker;N. R. Varrier;M. Lester
[1]在地磁平静的条件下，白天中纬度电离层主要受太阳辐射的影响：通常，电离层中的电子密度在太阳正午左右达到峰值。米尔斯顿山非相干散射雷达（ISR）先前的观测已经证明，在夏季，晚上的电子密度高于白天的密度。最近在北美和日本上空的中纬度超级双极光雷达网（SuperDARN）雷达的发展表明，夏季地面后向散射在夜间增强。SuperDARN观测数据进行比较，从磨石山ISR的数据，证实了所观察到的电子密度和地面后向散射晚上增强之间的直接关系。对黑石雷达一年多的数据统计显示，增强发生在4月至9月的日落期间的几个小时。SuperDARN和Millstone Hill ISR观测到的夜间增强与最近的卫星观测报告夏季北方半球中纬度地区大范围的电子密度增强有关。最后，从国际参考电离层（IRI）和水平风模式（HWM 07）的全球结果与以前发表的实验结果和建议的机制，即，热层水平风和地磁场配置的晚上增强。结果表明，IRI捕捉到了SuperDARN雷达和卫星观测到的夜间增强的特征。
[1] Under geomagnetically quiet conditions, the daytime midlatitude ionosphere is mainly influenced by solar radiation: typically, electron densities in the ionosphere peak around solar noon. Previous observations from the Millstone Hill incoherent scatter radar (ISR) have evidenced the presence of evening electron densities higher than daytime densities during the summer. The recent development of midlatitude Super Dual Auroral Radar Network (SuperDARN) radars over North America and Japan has revealed an evening enhancement in ground backscatter during the summer. SuperDARN observations are compared to data from the Millstone Hill ISR, confirming a direct relation between the observed evening enhancements in electron densities and ground backscatter. Statistics over a year of data from the Blackstone radar show that the enhancement occurs during sunset for a few hours from April to September. The evening enhancement observed by both SuperDARN and the Millstone Hill ISR is shown to be related to recent satellite observations reporting an enhancement in electron densities over a wide range of longitudes in the Northern Hemisphere midlatitude sector during summer time. Finally, global results from the International Reference Ionosphere (IRI) and the horizontal wind model (HWM07) are presented in relation with previously published experimental results and proposed mechanisms of the evening enhancement, namely, thermospheric horizontal winds and geomagnetic field configuration. It is shown that the IRI captures the features of the evening enhancement as observed by SuperDARN radars and satellites.