基于ZH-1卫星探测的太阳活动低年顶部电离层不规则结构的时空特征

利用ZH-1卫星2019、2020年的原位电子密度观测数据,对卫星观测范围,即地理纬度南北65°之间午夜后顶部电离层的不规则结构进行研究,得到如下结果.(1)午夜后顶部电离层不规则结构集中区主要分布在地磁赤道、中纬度以及较高纬度区,白天赤道异常峰值区为不规则结构的谷值区.(2)不同纬度区不规则结构随地理经度分布呈现出明...

Spatiotemporal features of topside ionospheric irregularities during low solar activity period detected by the ZH-1 Satellite

Topside ionospheric irregularities after midnight between 65°of southern and northern geographical latitudes,which is the observation range of the satellite,are studied using the in situ electron density measurements in 2019 and 2020 obtained by the ZH-1 Satellite.Results are as following:(1)Concentration area of topside ionospheric irregularities after midnight are mainly distributed at the geomagnetic equator,the geomagnetic mid-latitudes,and the higher latitudes,while locations of the daytime EIA(Equatorial Ionization Anomaly)crests are the irregularity valleys.(2)Obvious spatial evolution pattern is shown in the geographical longitude distribution of irregularities in different latitudinal regions.Wave number 2 longitudinal distribution is shown in the two higher latitudes with most irregularities being clustered around the longitudinal sectors where the geomagnetic poles are located;and also a wave number 2 longitudinal distribution is shown for the two mid-latitudes,but with opposite phases and amplitudes;and finally a wave number 4 longitudinal distribution is formed along the geomagnetic equator.(3)The seasonal variations of the irregularities in different geomagnetic latitudes are the local summer peaks in higher latitudes,the local summer peaks with a narrower duration in geomagnetic mid-latitudes,and finally two peaks at solstices and two valleys at equinoxes in the equatorial regions.(4)Besides the different seasonal pattern in equatorial region,another difference is the relative fewer irregularities at the Atlantic longitude sector compared to many irregularities in this sector obtained in previous studies.A wave number 4 pattern of geographical longitude distribution is shown along the geomagnetic equator with the peak being located at eastern Pacific and African sectors and valley being located at Asian and Atlantic sectors,which is consistent with the wave number 4 longitudinal pattern of the nighttime ionospheric background.(5)An obvious irregularity cluster is found at the geomagnetic mid-latitude in northern Atlantic,which is conjugated with the South Atlantic Anomaly(SAA)region,and the clustered irregularities are probably related with the particle precipitation in SAA region.All the clustered irregularities occur in the summer time of Northern Hemisphere,which is in contrast to the few irregularities of the Atlantic sector at the geomagnetic equator.Some results different from previous studies are obtained in this paper,which are helpful for a deep understanding of the ionosphere.As the spatiotemporal features are obtained from the irregularities after midnight in low solar activity period,these differences may be related with both the local time and the solar activity differences compared to previous studies.Unsolved problems still exist,and it is expected that more in-depth research will be conducted after more measurements are accumulated by the ZH-1 Satellite.