喉区极光的相关物理过程及产生机理研究

Based on auroral observations obtained at Yellow River Station, we newly defined an auroral form, called throat aurora. We have studied properties of throat aurora on the particle precipitation, dynamic process, and occurrence dependences. We noticed that throat aurora was always observed together with stripy diffuse aurora and the occurrence of throat aurora depends on factors both inside and outside the magnetosphere. We therefore suggested that the stripy diffuse auroras are associated with wedge-like cold plasmas in the dayside outer magnetosphere that are directly outflowed from the ionosphere. We also proposed that throat aurora is corresponding to localized deformation of the magnetopause, which may be caused by high speed jet impacting on the magnetopause or by magnetospheric cold plasma interacting with the magnetopause reconnection. Because the above suggestions are significant for understanding the coupling between solar wind and magnetosphere, our two publications on JGR have been successively selected as the cover images. In this proposal, we are planning to observationally confirm the above suggestions by using coordinative observations both from satellites, such as, MMS, THEMIS, and DMSP, and from ground stations in Antarctic and Arctic. In the final, we wish to build an integrated and self-consistent physical model about generation of throat aurora, which will be significant for the community and be the important contribution to the subject from China.

基于自主观测，申请人在前期研究中发现并定义了喉区极光，随后对其粒子源区特征、动态特征、观测统计特征展开系统研究，发现喉区极光总与条带状弥散极光相伴而生，且与磁层内部、外部因素及重联特征均表现出相关性，由此提出：与喉区极光相伴而生的条带状弥散极光对应日侧外磁层中的楔形冷等离子体、冷等离子体的楔形分布决定于电离层粒子上行、喉区极光对应磁层顶局地变形、该变形与磁鞘高速流冲击磁层顶或磁层冷等离子体影响磁层顶重联有关等系列新观点。鉴于上述新观点对深入理解太阳风-磁层耦合过程具有重要意义，相关成果连续两次被美国地球物理学报（JGR）选为封面文章。本项目拟利用MMS 、THEMIS、DMSP卫星和南北极地面联合观测，结合理论与数值模拟，进一步验证、核实、完善上述新观点，使其更加系统、清晰、可信，最终围绕喉区极光产生过程建立系统、自洽物理模型，有望产生重要国际影响，体现我国科研人员对本领域的研究贡献

项目执行前，我们发现了喉区极光，并对其粒子源区特征、动态特征、观测统计特征展开研究，注意到喉区极光总与条带状弥散极光相伴而生，且与磁层内部、外部因素及重联特征均表现出相关性，推测其可能反映重要的太阳风-磁层耦合过程，以此为基础，立足弄清喉区极光相关物理过程及产生机制展开本项目研究。项目执行过程中，紧扣项目研究目标，以“喉区极光”为主题词或关键字发表学术论文10篇，取得重要结果包括：1）提供了喉区极光对应磁层顶凹陷的坚实观测证据(Han et al., JGR, 2018)，研究成果被AGU会刊选为研究亮点；2）通过设计雷达与极光协同观测实验，给出喉区极光伴随磁层顶重联观测证据(Han et al., GRL, 2019)；3）提出可解释喉区极光诸多观测结果的概念模型（Han, Sci China Earth Sci , 2019）；4）首次给出伴随喉区极光的地磁观测特征(Selvakumaran et al., ESS，2020); 5) 首次提供了全球视野下喉区极光的卫星观测研究结果（Zhou et al., Sci China Earth Sci , 2020）；6）完成基于卫星观测的喉区极光统计研究（Selvakumaran et al., JGR, 2020）；7）首次取得喉区极光南北半球共轭观测特征，为喉区极光对应磁重联过程增添有力证据（Feng et al., JGR, 2020）; 8) 在美国加州大学伯克利分校Frey教授主笔的日侧极光综述文章中喉区极光被单列为一节介绍（Frey et al., Space Science Reviews, 2019）; 9）应邀为《极地研究》和AGU专辑“Dayside Magnetosphere Interactions”撰写喉区极光综述性文章（韩德胜等，极地研究，2018；Han, in AGU monograph, 2020）。此外，在项目支持下还取得若干其它重要成果，包括：1）完成孤立极光亮斑与质子沉降的相关性研究（Zhou et al., JGR, 2019）; 2)发现了一种新的极盖区极光弧15MLT-PCA（Han et al., GRL, 2020）; 3) 完成影响磁正午极光强度的关键因素研究（Qiu et al., GRL, 2021）。