基于三亚VHF雷达的场向不规则体观测研究：4.太阳活动低年夏季F区回波

太阳活动低年夏季，低纬电离层F区场向不规则体表现出与太阳活动高年和其他季节明显不同的特征.本文利用我国三亚站（18.4°N，109.6°E，地磁倾角纬度dip latitude 12.8°N）VHF雷达、电离层测高仪、GPS闪烁监测仪和美国C/NOFS卫星观测数据，研究了太阳活动低年夏季我国低纬电离层F区场向不规则体的基本特征.分析发现无论磁静日还是磁扰日，夏季电离层F区不规则体回波主要出现于地方时午夜以后，回波出现的时间较短，高度范围较小，伴随着扩展F出现，但没有同时段的L波段电离层闪烁.太阳活动低年夏季午夜后的低纬电离层F区不规则体回波，可能并不总是与赤道等离子体泡沿磁力线向低纬地区的延伸相关，而可能由本地Es等扰动过程引起.

Observations on the field-aligned irregularities using Sanya VHF radar：4. June solstitial F-region echoes in solar minimum

Observation reveals remarkable difference in morphology of the F-region irregularities in summer of solar minimum compared with that in equinox and solar maximum. In this paper, the characteristic of low latitude ionospheric irregularities in East Asia during the June solstice of solar minimum is analysed by utilizing the measurements of VHF radar, ionosonde and GPS scintillation monitor of Sanya observatory, as well as the in-situ plasma density measurement of C/NOFS satellite. No matter on quiet or disturbed days, F region ionospheric irregularities were observed frequently at post-midnight, accompanied by equatorial spread F but without L band ionospheric scintillation. The extent of height and duration of the irregularity echoes were not as large as that of post-sunset ones. The irregularity echoes starting at the post-midnight hours are not always associated with the equatorial plasma bubble, but resemble localized origin such as Es activity.