Trattner K J, Petrinec S M, Fuselier S A
LASP, University of Colorado, Boulder, CO USA.
Lockheed Martin ATC, Palo Alto, CA USA.
Space Sci Rev. 2021;217(3):41. doi: 10.1007/s11214-021-00817-8. Epub 2021 Mar 29.
One of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth's magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model's inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth's magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.
关于磁重联的一个主要问题是，特定的太阳风和行星际磁场条件如何影响地球磁层顶处重联发生的位置。文献中讨论了两种重联情形：a）反平行重联和b）分量重联。早期的航天器观测仅限于检测磁层顶边界层中的加速离子束，以确定重联X线位置相对于航天器的大致方向。对磁层顶重联位置的更深入了解源于极轨成像仪对电离层发射的观测。这些观测以及对加速离子束的观测表明，两种情形都发生在磁层顶。利用尖点区域中沉降离子的飞行时间效应以及沉降和镜像离子群体的截止速度的改进方法，被用于确定各种太阳风条件下磁层顶重联的位置。这些方法的结果已被用于构建一个称为最大磁切变模型的经验性重联X线模型。自该模型建立以来，多项测试证实了其有效性，并针对某些太阳风条件对模型进行了修正。这篇综述文章总结了地球磁层顶处磁重联位置的观测证据，重点介绍了最大磁切变模型的特性和效能。
