Equatorial plasma depletion precursor signatures and onset observed at 11° south of the magnetic equator
Equatorial plasma depletion precursor signatures and onset observed at 11° south of the magnetic equator
复制标题
赤道等离子体耗尽前兆特征和观测到的磁赤道以南 11° 起始点
DOI：
--
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
J. Araya
中科院分区：
文献类型：
--
作者：
E. J. Weber;S. Basu;T. Bullett;C. Valladares;G. Bishop;K. Groves;H. Kuenzler;P. Ning;P. J. Sultan;R. Sheehan;J. Araya
1994年10月1日在智利阿瓜维德(S磁纬11.3°)对日落后赤道电离层的结构和动力学进行了联合无线电和光学测量。这些测量结果清楚地显示出在当地时间2000时F层底部有一个南北排列的起伏或涟漪，看起来像是630.0 nm气辉向东传播的减少，这类似于数字便携式电离层探测仪测量中的电离层扰动，并导致全球定位系统卫星测量中的总电子含量下降。这一特征最初的发展是在一个光滑的、无结构的电离层中进行的，它朝向东方，远离磁赤道。在2020年LT开始在电离图中形成扩展F，同时，利用以L频段发射的全球定位系统卫星星座提供的贯穿天空的多条射线路径，探测到卫星信号闪烁的局部起始。沿同一磁场线对秘鲁安康的超高频闪烁测量表明，在S地面温度11°时，在磁赤道上空出现了强烈的闪烁和电离层不规则性，几乎是在60min之前。观测表明，预计将出现在磁赤道较早发展的损耗和闪烁区域内的东西向电场沿着磁力线映射到较低海拔和较高纬度，导致起伏或穹顶状结构，然后沿磁通量管演变为完全发育的损耗(伴随着相关的电离层不规则)。
Coordinated radio and optical measurements of the structure and dynamics of the postsunset equatorial ionosphere were conducted on October 1, 1994, from Agua Verde, Chile (11.3°S magnetic latitude (MLat)). The measurements clearly show a north-south aligned undulation or ripple on the bottomside of the F layer at 2000 LT, appearing as an eastward propagating decrease in the 630.0-nm airglow, resembling a traveling ionospheric disturbance in the digital portable ionosonde measurements and causing a total electron content decrease in the Global Positioning System (GPS) satellite measurements. The initial development of this feature, toward the east and away from the magnetic equator, took place in an otherwise smooth, unstructured ionosphere. Spread F began to develop in the ionograms at 2020 LT, and, at this same time, local onset of satellite signal scintillation was detected using the multiple ray paths throughout the sky available from the GPS satellite constellation transmitting at L band frequencies. UHF scintillation measurements from Ancon, Peru, along the same magnetic field line, show that intense scintillation and ionospheric irregularities had developed over the magnetic equator almost 60 min prior to their development at 11°S MLat. The observations suggest that the east-west electric field expected to be present within the earlier developed depletion and scintillation region at the magnetic equator mapped along magnetic field lines to lower altitudes and higher latitudes, resulting in an undulation or dome-shaped structure, before evolving into a fully developed depletion (with associated ionospheric irregularities) all along the magnetic flux tube.