高纬日侧电离层离子上行的地磁活动依赖性研究  

Geomagnetic activity dependences of high-latitude dayside ionospheric ion upflows

作　　者：周康俊 蔡红涛[1,2] 李影[1,2] 胡坤[1,2] 黄定娟 张琬 马淑英[1,2] 

机构地区：[1]武汉大学电子信息学院,武汉430072 [2]武汉大学空间环境与大地测量教育部重点实验室,武汉430072

出　　处：《地球物理学报》2018年第2期423-436,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金委创新群体项目(41521063);国家自然科学基金项目(41374159;41431073;41574148)资助

摘　　要：本文对比分析了太阳活动高、低年期间高纬日侧顶部电离层离子上行随地磁活动水平的变化特征.按地磁活动水平,将DMSP卫星在太阳活动高年(2000—2002年,F13和F15)及太阳活动低年(2007—2009年,F13;2007—2010年,F15)期间的SSIES离子漂移速度观测数据分为三组:地磁平静期(Kp<3),中等地磁扰动期(3≤Kp<5)和强地磁活动期(Kp≥5),分别统计分析了高纬日侧顶部电离层离子上行特征的时空分布.对比分析发现:(1)太阳活动低年期间,高纬日侧电离层离子上行发生率以及上行速度峰值均是太阳活动高年的2倍多,而离子上行通量峰值只有高年的1/6-1/4;(2)在相同太阳活动条件下,地磁活动水平对日侧电离层离子上行发生率峰值的影响并不明显,但对离子上行发生率的空间分布有着显著的控制作用:电离层离子上行高发区随地磁活动向低纬度扩展,并在强地磁活动期间呈现饱和的趋势;(3)日侧顶部电离层等离子体似乎存在两个效率相当的上行区域,一个位于极尖/极隙区纬度附近,离子可沿开放磁力线上行进入磁尾;另一个位于晨侧亚极光区附近,离子沿闭合磁力线上行,有可能进入日侧等离子体层边界层.Characteristics of high-latitude dayside ionospheric bulk ion upflows varying with various geomagnetic activity levels during solar maximum/minimum are investigated in this paper. According to the Kp index, DMSP satellites observations during solar maximum （2000- 2002, F13 and F15） and minimum （2007-2009,F13;2007-2010, F15） are binned into three groups： geomagnetic quiet （Kp〈3）, moderate disturbances （3≤Kp〈5） and strong geomagnetic activity （Kp≥5）, then spatial and temporal distributions of ion upflows at dayside ionosphere are analyzed, respectively. Analysis shows that the bulk ion upflows occurrence and speed at dayside ionosphere during solar minimum are more than 2 times larger than those during solar maximum, whilst ion upward fluxes during solar maximum are 4 - 6 times higher than that during solar minimum. The occurrence of dayside ionospheric bulk ion upflows show no remarkable responses to variations of geomagnetic activity under the same solar activity condition, whilst the upward ions spatial distributions exhibit strong dependences on it. Regions of up-flowing ions being frequently observed usually move equatorwards with the increase of geomagnetic activities, and it tends to be saturated during periods of strong geomagnetic disturbances. Observations of the DMSP fleets reveal that there seems to be two regions at the dayside ionosphere with comparable efficiency of bulk up-flowing ions. One of them lies at the cusp/cleft regions, where ionospheric ions move upwards along open field lines towards magnetic tail. The other one is situated in dawn-side sub-auroral region, where ionospheric ions up-flow along closed field lines, possible reach boundary layers of dayside plasmasphere.

关 键 词：电离层离子上行 地磁活动 高纬电离层 太阳活动 

分 类 号：P352[天文地球—空间物理学]