The baselevel ionospheric trough
The baselevel ionospheric trough
复制标题
DOI：
10.1029/ja082i032p05129
复制
发表时间：
1977-11
影响因子：
--
通讯作者：
M. Mendillo;C. Chacko
中科院分区：
文献类型：
--
作者：
M. Mendillo;C. Chacko
1971年12月获取的顶部F区的“国际电离层研究卫星2号”（Isis 2）电子密度剖面，使得在一组最佳地球物理条件下对电离层“主槽”区域进行了详细研究。在21天的时间内，总共利用了卫星的30次单独穿越，以确定北半球隆冬、当地时间午夜以及地磁活动极低条件下该槽的特征。从这个严格一致的数据库中获得的形态描述被称为“基准槽”。在40° - 80°校正地磁纬度范围内，最大高度（hmax）处槽的纬度剖面显示，虽然赤道向边缘和槽最小值是较宽的特征（分别为7°和10°），但极向壁很陡峭（约1.5°）。赤道向边缘和槽最小值在较高高度往往失去其明显特征，而极向壁增强的幅度从450公里到950公里几乎保持恒定在2.15。发现槽的极向壁在纬度上比弥散极光赤道向边缘的统计位置低1° - 2°。顶部密度与峰值密度的比率表明，从中间纬度到槽最小值，电子密度（Ne）随高度（h）的分布曲线形状是恒定的。在最小值区域内，顶部形状发生相对快速的变化，这标志着以高氢离子/氧离子转换高度为特征的轻离子耗尽区域。转换高度增强的北端与磁层等离子体层顶的统计位置相符。等离子体温度（电子温度Te + 离子温度Ti）的估算表明，在槽最小值区域内只有适度的增强。
Isis 2 electron density profiles of the topside F region obtained during December 1971 have led to a detailed examination of the ionosphere's ‘main trough’ region under an optimum set of geophysical conditions. A total of 30 individual satellite passes during a 21-day period were used to determine the trough's characteristic features under the conditions of midwinter in the northern hemisphere, midnight local time, and very low magnetic activity. The morphological description obtained from this rigidly consistent data base is termed the ‘baselevel trough.’ The latitudinal profile of the trough at hmax over the 40°–80° corrected geomagnetic latitude range shows that while the equatorward edge and the trough minimum are wide features (7° and 10°, respectively), the poleward wall is sharp (∼1½°). The equatorward edge and the trough minimum tend to lose their distinct identities toward higher altitudes, while the magnitude of the poleward wall enhancement remains nearly constant at 2.15 from 450 to 950 km. The trough's poleward wall is found 1°–2° lower in latitude than the statistical position of the equatorward edge of the diffuse aurora. Ratios of topside densities to the peak density reveal that the shape of the Ne(h) profiles is constant from mid-latitudes to the trough minimum. Within the minimum a relatively rapid change in topside shape occurs which marks the light ion depletion region characterized by high H+/O+ transition heights. The northern terminus of the transition height enhancement agrees with the statistical position of the magnetospheric plasmapause. Estimates of plasma temperature (Te + Ti) show only modest enhancements within the trough minimum.