Comparison of large-scale Birkeland currents determined from Iridium and SuperDARN data
Comparison of large-scale Birkeland currents determined from Iridium and SuperDARN data
复制标题
根据 Iridium 和 SuperDARN 数据确定的大尺度伯克兰电流的比较
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
R. Barnes
中科院分区：
文献类型：
--
作者：
D. Green;C. Waters;B. Anderson;H. Korth;R. Barnes
抽象的。伯克兰电流J||将高纬度电离层与近地空间环境电耦合。可以利用电离层电场的发散来近似伯克兰德电流的空间分布，假设电导梯度为零，使得。本文利用超级双极光雷达网(SuperDARN)得到的电场数据进行了计算，并与60°磁纬60°Iridium卫星星座得到的全球Birkland电流分布进行了比较。我们发现，零电导梯度的假设通常是一个很差的近似。在白天，在SuperDARN电场受雷达回波约束的地区，Iridium资料得到的与J||之间的上下流区域位置是合理的，主要洋流特征的纬向位置相差不到3°。结果还表明，在正午以外，由电导梯度引起的电流可能比分量大。通过将雷达覆盖区域的估计与来自DMSP卫星粒子数据的电导梯度的现场估计相结合，与Iridium派生的J||的一致性得到了显著改善。然而，使用电离层电导的经验模型没有考虑电导梯度电流项。在雷达数据稀疏或不存在的地区，因此受统计势模型的约束，该近似与根据Iridium数据计算的J||不一致。
Abstract. The Birkeland currents, J||, electrically couple the high latitude ionosphere with the near Earth space environment. Approximating the spatial distribution of the Birkeland currents may be achieved using the divergence of the ionospheric electric field, , assuming zero conductance gradients such that . In this paper, electric field data derived from the Super Dual Auroral Radar Network (SuperDARN) are used to calculate , which is compared with the Birkeland current distribution derived globally from the constellation of Iridium satellites poleward of 60° magnetic latitude. We find that the assumption of zero conductance gradients is often a poor approximation. On the dayside, in regions where the SuperDARN electric field is constrained by radar returns, the agreement in the locations of regions of upward and downward current between and J|| obtained from Iridium data is reasonable with differences of less than 3° in the latitudinal location of major current features. It is also shown that away from noon, currents arising from conductance gradients can be larger than the component. By combining the estimate in regions of radar coverage with in-situ estimates of conductance gradients from DMSP satellite particle data, the agreement with the Iridium derived J|| is considerably improved. However, using an empirical model of ionospheric conductance did not account for the conductance gradient current terms. In regions where radar data are sparse or non-existent and therefore constrained by the statistical potential model the approximation does not agree with J|| calculated from Iridium data.