极区Hall电流经度差异特征的统计学研究:CHAMP卫星观测  

Statistical study of longitudinal variations of Hall currents at high latitudes:CHAMP observation

作　　者：张静[1] 王慧[1] 张科灯 刘丁维 万欣[1] 郑志超 ZHANG Jing WANG Hui＂ ZHANG Ke-Deng LIU Ding-Wei WAN Xin ZHENG Zhi-Chao(Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, Chin)

机构地区：[1]武汉大学电子信息学院空间物理系,武汉430072

出　　处：《地球物理学报》2017年第10期3707-3717,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41674153;41521063;41431073)资助

摘　　要：本文利用2001至2010年间CHAMP(CHallenging Minisatellite Payload)卫星标量磁力仪(Overhauser Magnetometer)观测的磁场数据,反演得到电离层霍尔(Hall)电流,并且对极区电离层Hall电流的特征进行了统计学研究.研究主要关注平静期,即重联电场小于2 mV·m^(-1)条件下,在磁纬60°至90°范围内的Hall电流在不同太阳活动、季节、磁经度、磁地方时等条件下的变化特征.研究发现:Hall电流具有明显的经度差异,在南北半球呈现显著一波经度结构,而且南北半球反相,即北半球电流密度呈现峰-谷-峰结构,而南半球呈现谷-峰-谷结构.Hall电流密度的经度结构与太阳活动紧密相关,太阳活动高年经度差异最大,太阳活动中年经度差异次之,太阳活动低年经度差异最小.研究发现,在磁地方时为10-14MLT的白天,影响Hall电流的因素主要是太阳辐射;而磁地方时为21-03MLT的夜晚,除了电导率的影响之外,可能存在其他的重要的物理过程影响着Hall电流的经度分布.本文还研究了与电流相关的焦耳热的经度分布情况,发现其在南北半球分别呈现单峰、单谷结构,经度差异亦十分明显.By using the scalar magnetic field measurements from the Overhauser Magnetometer on board CHAllenging Minisatellite Payload （CHAMP）, the ionosphere Hall currents are studied during years of 2001-2010. The work mainly focuses on the longitudinal and diurnal variations of Hall currents during different seasons and solar activities when the merging Electric field is less than 2 mV·m-1. Hall currents show obvious longitudinal variations with single peak and single trough in the northern and southern hemispheres. The currents in the northern and southern hemisphere are almost anti-phase with each other. The longitudinal difference of Hall current is larger at solar maximum and weaker at solar minimum. In the daytime, during 10：00-14：00 magnetic local time, the factor controlling the longitudinal variations of Hall currents is mainly the solar irradiation, while at night, during 21：00-03：00 magnetic local time, factors affecting currents are more complicated and other important physical processes are more important than the ionospheric conductivity. Joule heating exhibits a similar longitudinal and diurnal structure as those of Hall currents in the two hemispheres.

关 键 词：Hall电流 经度差异 太阳辐射 粒子沉降 

分 类 号：P352[天文地球—空间物理学]