Characteristics of equatorial electrojet over India determined from a thick current shell model
Characteristics of equatorial electrojet over India determined from a thick current shell model
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由厚海流壳层模型确定的印度上空赤道电喷流特征
DOI：
10.1016/j.jastp.2012.10.014
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发表时间：
2013
影响因子：
1.9
通讯作者：
N,Yumoto K
中科院分区：
文献类型：
--
作者：
Rabiu;A. B.; Onwumechi l i;C. A.; Nagarajan;N,Yumoto K
第一次所需的五个参数，以充分描述Onwumechili的复合厚电流壳模型格式的赤道电射流已评估从一个单一的自主设置的地面数据在太阳能最低。考虑到垂直电离层电流的厚电流壳模型允许同时确定射流的宽度和厚度。在印度扇区，计算出的电射流参数的年平均值为：中心正向电流峰值强度62.97±2.73A/km，返回电流峰值强度19.43±2.49A/km，返回电流峰值与正向电流峰值强度之比0.312±0.052;电流焦点间的总正向电流为19.01±1.74kA，距电流中心的半纬宽或焦距为2.7±0.18°，返回电流峰值位置距电流中心的距离为5.31±0.19°;峰值电流密度的半厚度为0.063±0.003°，电流中心的纬向延伸为9.25±2.赤道电射流EEJ中心的倾角为−0.190±0.003°。EEJ中心的倾角纬度从清晨急流的上升开始向倾角赤道方向持续北移，从年平均的−0.193°移到LT约1100小时的−0.186°，之后开始向南退缩到黄昏。结果表明，随着电射流中心向北（南）靠近（远离）磁倾角赤道方向移动，电射流的强度增大（减小）。EEJ厚度的日变化与其电流强度和半宽的日变化相反。赤道电急流EEJ的厚度具有一致的日变化，黎明时约为0.066°，1100 hLT时最小，黄昏时开始增加。越大，越大。平均日间流强Jo和正向流Ifwd的季节变化顺序为E>D> J。然而，EEJ参数的日变化具有季节依赖性，因为所有参数的季节变化顺序在白天的每个小时都不一致。
For the first time the five parameters required to fully describe Onwumechili’s composite thick current shell model format of equatorial electrojet have been evaluated from a single autonomous set of ground data at solar minimum. The thick current shell model, which takes into account the vertical ionospheric currents, permits both the width and the thickness of the jet to be determined simultaneously. The mean annual values of the electrojet parameters evaluated over India sector are: the peak intensity of the forward current at its centre, 62.97±2.73A/km; the peak intensity of the return current, 19.43±2.49A/km; the ratio of the peak return to the peak forward current intensity, 0.312±0.052; the total forward current flowing between the current foci, 19.01±1.74kA; half of the latitudinal width or the focal distance from the current centre, 2.7±0.18°; the distance of the peak return current location from the current centre, 5.31±0.19°; the half thickness of the peak current density, 0.063±0.003°; the latitudinal extent of the current from its centre, 9.25±2. 08°; and the dip latitude of the equatorial electrojet EEJ centre −0.190±0.003°. The dip latitude of the centre of EEJ exhibits a consistent northward migration towards the dip equator from the rising of the jet at dawn from an annual average of −0.193° to about −0.186° at about 1100h LT, after which it begins to recede southward towards the dusk. Our results show that the electrojet becomes more (less) intensified as the centre of the electrojet moves northwards (southwards) towards (away from) the dip equator. The diurnal variation of the thickness of the EEJ is opposite that of its current intensity and half width. The thickness of equatorial electrojet EEJ exhibits a consistent diurnal variation such that it decreases from about 0.066° at dawn to the minimum at about 1100hLT and then begins to increase towards the dusk. The wider (thicker) the EEJ, the stronger (weaker) the EEJ strength. The order of seasonal variation of the mean daytime current intensity Joand forward current Ifwdis E>D>J. However, the diurnal variations of the EEJ parameters exhibit seasonal dependence as the order of seasonal variation is not uniform at every hour of daytime for all the parameters.