Simultaneous ground and satellite observations of an isolated proton arc at subauroral latitudes
Simultaneous ground and satellite observations of an isolated proton arc at subauroral latitudes
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DOI：
10.1029/2006ja012135
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发表时间：
2007-04-06
影响因子：
2.8
通讯作者：
Rich, F. J.
中科院分区：
文献类型：
--
作者：
Sakaguchi, K.;Shiokawa, K.;Rich, F. J.
[1] 2005 年 9 月 5 日，我们使用地面全天空成像仪在 557.7 nm、630.0 nm 和 486.1 nm (H beta) 波长下在加拿大阿萨巴斯卡站（MLAT：北纬 62 度）观察到了孤立的质子弧。该弧类似于最近由 IMAGE 卫星观测到的分离质子弧 [Immel 等，2002]。电弧出现在 0500-0640 UT (2100-2240 MLT)，与电磁离子回旋加速器 (EMIC) 波频率范围内的强 Pc 1 地磁脉动一致。在世界标准时间 0550 发生的一次小型亚暴的后期增长和扩张阶段，孤立弧并没有改变其结构和强度。从 NOAA 17 卫星获得的粒子数据中，我们发现孤立弧与 L 处 30-80 keV 能量范围内离子沉淀通量的局部增强有关，类似于 4。在两个纬度上分离的区域也观察到了捕获离子通量增强（环流离子）。局部离子沉淀位于内环电流离子的外边界。 DMSP F13 卫星观测到南半球电弧共轭点附近电离层等离子体槽的特征。该槽被认为与等离子层顶相连。这些结果表明，孤立电弧的源区位于等离子层顶附近和环电流中。我们得出的结论是，在亚极光纬度观察到的孤立质子弧是由 EMIC 波引起的，EMIC 波在等离子层顶附近产生，并将环流质子共振散射到损失锥中。
[1] We observed an isolated proton arc at the Athabasca station (MLAT: 62 degrees N) in Canada on 5 September 2005, using a ground-based all-sky imager at wavelengths of 557.7 nm, 630.0 nm, and 486.1 nm (H beta). This arc is similar to the detached proton arc recently observed by the IMAGE satellite [Immel et al., 2002]. The arc appeared at 0500-0640 UT (2100-2240 MLT), coincident with strong Pc 1 geomagnetic pulsations in the frequency range of the electromagnetic ion cyclotron (EMIC) wave. The isolated arc did not change its structure and intensity during the late growth and expansive phases of a small substorm that occurred at 0550 UT. From particle data obtained by the NOAA 17 satellite, we found that the isolated arc was associated with the localized enhancement of ion precipitation fluxes at an energy range of 30-80 keV at L similar to 4. Trapped ion flux enhancements ( ring current ions) were also observed at two latitudinally separated regions. The localized ion precipitation was located at the outer boundary of the inner ring current ions. The DMSP F13 satellite observed signatures of an ionospheric plasma trough near the conjugate point of the arc in the Southern Hemisphere. The trough is considered to be connected to the plasmapause. These results indicate that the source region of the isolated arc was located near the plasmapause and in the ring current. We conclude that the observed isolated proton arc at subauroral latitudes was caused by the EMIC waves, which were generated near the plasmapause and resonantly scattered the ring current protons into the loss cone.