Coordinated interhemispheric SuperDARN radar observations of the ionospheric response to flux transfer events observed by the cluster spacecraft at the high-latitude magnetopause
Coordinated interhemispheric SuperDARN radar observations of the ionospheric response to flux transfer events observed by the cluster spacecraft at the high-latitude magnetopause
复制标题
DOI：
10.5194/angeo-21-1807-2003
复制
发表时间：
2003-08
影响因子：
1.9
通讯作者：
J. Wild;S. Milan;S. Cowley;M. Dunlop;C. Owen;J. Bosqued;M. Taylor;J. Davies;M. Lester;N. Sato;A. Yukimatu;A. Fazakerley;A. Balogh;H. Rème
中科院分区：
文献类型：
--
作者：
J. Wild;S. Milan;S. Cowley;M. Dunlop;C. Owen;J. Bosqued;M. Taylor;J. Davies;M. Lester;N. Sato;A. Yukimatu;A. Fazakerley;A. Balogh;H. Rème
摘要。2001年2月14日世界时10时，欧空局星团的四个航天器在正午后沿出站轨道接近北半球高纬度磁层顶。此时，发生在日面磁层顶上的行星际磁场是向南和向暗的（BZ负，BY正），在1个多小时前从北向转向。当他们接近磁层顶时，星团飞船上的磁场、电子和离子传感器观测到磁层通量传递事件（FTEs）的特征场和粒子特征。在穿越边界层和磁层顶之后，宇宙飞船继续观察磁鞘中fte的进一步特征。在高纬度正午后磁层顶持续的脉冲重联期间，Cluster航天器的足迹分别位于位于北半球和南半球的SuperDARN芬兰和Syowa East雷达的视场中。本研究在Wild等人（2001）的初步调查基础上进行了扩展，首次将fte的原位磁场和等离子体特征（这里是由Cluster 1航天器观测到的）与两个半球共轭电离层的同步流调制进行了比较。在研究期间，共轭电离层中的流动扰动表现为典型的“脉冲电离层流”（pif）和“极向移动雷达极光形式”（PMRAFs）。我们证明，在磁层顶响应fte激发的电离层流不是那些在空间有限的重连接区域所期望的，在集群1航天器附近的某个地方。通过研究高纬度电离层的大、小规模流动，以及在这段时间内半球间的对应关系，我们得出结论，导致pif / pmraf产生的重联过程必须在中午前后磁层顶的许多（至少4）小时的磁局地时间内延长。关键字。电离层（等离子体对流）.磁层物理（磁层-电离层相互作用。磁层结构和动力学）
Abstract. At 10:00 UT on 14 February 2001, the quartet of ESA Cluster spacecraft were approaching the Northern Hemisphere high-latitude magnetopause in the post-noon sector on an outbound trajectory. At this time, the interplanetary magnetic field incident upon the dayside magnetopause was oriented southward and duskward (BZ negative, BY positive), having turned from a northward orientation just over 1 hour earlier. As they neared the magnetopause the magnetic field, electron, and ion sensors on board the Cluster spacecraft observed characteristic field and particle signatures of magnetospheric flux transfer events (FTEs). Following the traversal of a boundary layer and the magnetopause, the spacecraft went on to observe further signatures of FTEs in the magnetosheath. During this interval of ongoing pulsed reconnection at the high-latitude post-noon magnetopause, the footprints of the Cluster spacecraft were located in the fields-of-view of the SuperDARN Finland and Syowa East radars located in the Northern and Southern Hemispheres, respectively. This study extends upon the initial survey of Wild et al. (2001) by comparing for the first time in situ magnetic field and plasma signatures of FTEs (here observed by the Cluster 1 spacecraft) with the simultaneous flow modulations in the conjugate ionospheres in the two hemispheres. During the period under scrutiny, the flow disturbances in the conjugate ionospheres are manifest as classic "pulsed ionospheric flows" (PIFs) and "poleward moving radar auroral forms" (PMRAFs). We demonstrate that the ionospheric flows excited in response to FTEs at the magnetopause are not those expected for a spatially limited reconnection region, somewhere in the vicinity of the Cluster 1 spacecraft. By examining the large- and small-scale flows in the high-latitude ionosphere, and the inter-hemispheric correspondence exhibited during this interval, we conclude that the reconnection processes that result in the generation of PIFs/PMRAFs must extend over many (at least 4) hours of magnetic local time on the pre- and post-noon magnetopause. Key words. Ionosphere (plasma convection) – Magnetospheric physics (magnetosphere-ionosphere interactions; magnetospheric configuration and dynamics)