The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan
The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan
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DOI：
10.1007/s11431-012-4800-2
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发表时间：
2012-03
期刊：
影响因子：
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通讯作者：
B. Ning;L. Hu;Guozhu Li;Libo Liu;W. Wan
中科院分区：
文献类型：
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作者：
B. Ning;L. Hu;Guozhu Li;Libo Liu;W. Wan
海南三亚甚高频雷达（18.4°N，109.6°E，倾角12.8°N）是中国大陆第一部探测低纬电离层不规则结构的相干后向散射雷达。本文利用2009年2月至2010年3月期间的雷达资料，首次给出了低纬电离层E区和F区不规则性的初步结果。E区场向不规则体（FAI）雷达回波的多普勒速度约为几十米/秒，而多普勒谱宽明显大于速度，可达100米/秒，表明观测到的E区FAI属于2型不规则体。FAI的距离时间强度（RTI）图的观察表明，E区的不规则性最经常发生在夜间的高度范围内85-115公里，很少在下午的时间观察到。E区FAI的发生率在春季（2月-5月）达到最大值，峰值超过80%。与回波有关的FAI最强发生高度主要在100 km左右，低于h 'E，相差10-20 km。在90-100公里的狭窄高度范围内，FAI回波通常被探测到，而冬至似乎是FAI回波发生的最小时期。此外，在太阳活动极小期午夜前的扩展F事件期间，同时进行的雷达和GPS观测表明，GPS L波段的显著振荡与F区域等离子体羽流结构的出现相吻合，该结构延伸到450公里的高度。
Sanya VHF radar (18.4°N, 109.6°E, dip latitude 12.8°N) at Hainan Island is the first coherent backscatter radar for sounding low-latitude ionospheric irregularities in the mainland of China. In this paper, we present the first results of low-latitude ionospheric E and F region irregularities using the radar data during the period from February 2009 to March 2010. The Doppler velocity of radar echoes from E region field aligned irregularities (FAIs) was about several tens of meters per second, while the Doppler spectral width was appreciably larger than the velocity, and could reach one hundred meters per second, indicating that the observed E region FAIs belonged to type 2 irregularities. The observations of range time intensity (RTI) maps of FAIs showed that E region irregularities most often occurred at night within the altitude range 85–115 km, and were rarely observed at afternoon hours. The percentage occurrence of E region FAIs maximized during spring months (Feb.–May) with a peak value over 80%. The heights at which the strongest echo related FAIs occurred were mainly around 100 km, lower than h’Es and the difference is mostly 10–20 km. December solstice seemed to be the minimum period of occurrence when the FAI echoes were commonly detected at a narrow altitude range 90–100 km. Moreover, simultaneous radar and GPS observations during spread F events in the pre-midnight hours of solar minimum revealed that significant GPS L band scintillations coincided with the appearance of F region plasma plume structures, which extended up to 450 km in altitude.