Genestreti K J, Nakamura T K M, Nakamura R, Denton R E, Torbert R B, Burch J L, Plaschke F, Fuselier S A, Ergun R E, Giles B L, Russell C T
Space Research Institute Austrian Academy of Sciences Graz Austria.
Now at Space Science Center University of New Hampshire Durham NH USA.
J Geophys Res Space Phys. 2018 Nov;123(11):9130-9149. doi: 10.1029/2018JA025711. Epub 2018 Nov 10.
We investigate the accuracy with which the reconnection electric field E can be determined from in situ plasma data. We study the magnetotail electron diffusion region observed by National Aeronautics and Space Administration's Magnetospheric Multiscale (MMS) on 11 July 2017 at 22:34 UT and focus on the very large errors in E that result from errors in an L M N boundary normal coordinate system. We determine several L M N coordinates for this MMS event using several different methods. We use these M axes to estimate E . We find some consensus that the reconnection rate was roughly E = 3.2 ± 0.6 mV/m, which corresponds to a normalized reconnection rate of 0.18 ± 0.035. Minimum variance analysis of the electron velocity (MVA-v ), MVA of E, minimization of Faraday residue, and an adjusted version of the maximum directional derivative of the magnetic field (MDD-B) technique all produce reasonably similar coordinate axes. We use virtual MMS data from a particle-in-cell simulation of this event to estimate the errors in the coordinate axes and reconnection rate associated with MVA-v and MDD-B. The L and M directions are most reliably determined by MVA-v when the spacecraft observes a clear electron jet reversal. When the magnetic field data have errors as small as 0.5% of the background field strength, the M direction obtained by MDD-B technique may be off by as much as 35°. The normal direction is most accurately obtained by MDD-B. Overall, we find that these techniques were able to identify E from the virtual data within error bars ≥20%.
我们研究了根据原位等离子体数据确定重联电场E的准确性。我们研究了美国国家航空航天局磁层多尺度任务（MMS）于2017年7月11日世界时22:34观测到的磁尾电子扩散区，并关注由L-M-N边界法向坐标系中的误差导致的E的巨大误差。我们使用几种不同的方法为该MMS事件确定了几个L-M-N坐标。我们使用这些M轴来估计E。我们发现一些共识，即重联率大致为E = 3.2±0.6 mV/m，这对应于归一化重联率为0.18±0.035。电子速度的最小方差分析（MVA-v）、E的MVA、法拉第残差最小化以及磁场最大方向导数的调整版本（MDD-B）技术都产生了相当相似的坐标轴。我们使用该事件的粒子模拟中的虚拟MMS数据来估计与MVA-v和MDD-B相关的坐标轴和重联率的误差。当航天器观测到明显的电子射流反转时，L和M方向最可靠地由MVA-v确定。当磁场数据的误差小至背景场强的0.5%时，通过MDD-B技术获得的M方向可能偏差多达35°。法向方向最准确地由MDD-B获得。总体而言，我们发现这些技术能够在误差范围内≥20%的情况下从虚拟数据中识别出E。
