CSES卫星观测的赤道电集流特征  

Characteristics of equatorial electrojet revealed by CSES observation

作　　者：周云良[1,2] 杨艳艳 朱劼 熊超[1,2] 王丰珏[1] 泽仁志玛 申旭辉 ZHOU YunLiang;YANG YanYan;ZHU Jie;XIONG Chao;WANG FengJue;Zeren Zhima;SHEN XuHui(Department of Space Physics,School of Electronic Information,Wuhan University,Wuhan 430072,China;Hubei Luojia Laboratory,Wuhan 430079,China;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China)

机构地区：[1]武汉大学电子信息学院,武汉430072 [2]湖北珞珈实验室,武汉430079 [3]应急管理部国家自然灾害防治研究院,北京100085

出　　处：《地球物理学报》2022年第11期4141-4151,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金面上项目(42174186);湖北珞珈实验室专项基金(220100011);中欧龙计划项目(59236)联合资助.

摘　　要：本文利用2018年8月到2019年12月期间我国张衡一号电磁监测试验卫星(CSES)所观测的地磁数据,反演了赤道电集流(EEJ)电流密度的纬度剖面;通过选取的4729个清晰的EEJ事件,分析了在地方时(LT)14∶00附近的EEJ特征.研究结果表明:在地磁平静期间,CSES卫星观测的EEJ电流密度的峰值位于磁赤道附近,其平均幅度约为27 mA·m^(-1).该幅度小于CHAMP和Swarm卫星的观测结果,这与2018—2019年期间太阳活动水平较低(平均F_(10.7)指数约为70 sfu)有关,此外也与CSES轨道所处的地方时相关.平均而言,EEJ的主瓣宽度约为4°,主瓣和旁瓣的峰值电流密度之比约为2.7;在本文所关注的事件中,东向EEJ事件约占83%,西向EEJ事件约占17%;这个比例与CHAMP卫星的观测结果稍有不同,与14∶00 LT附近西向EEJ出现的概率较低有关.东向EEJ的峰值电流密度对经度、季节和太阳辐射水平有显著的依赖性.EEJ峰值密度随经度变化呈现明显的4波结构,可归因于低层大气非迁移潮汐的作用.EEJ峰值电流密度有明显的季节依赖,其幅度在春秋分较大,冬夏季较小.在2018—2019年期间,尽管太阳活动水平较低,EEJ峰值密度随太阳辐射水平的增加而增加.By utilizing the magnetic field measurements from the high precision magnetometer(HPM)onboard the China Seismo-Electromagnetic Satellite(CSES),also called Zhangheng-1,the equatorial electrojet(EEJ)at 14∶00 local time(LT)from August 2018 to December 2019 are investigated in this study.For the selected 4729 electrojet events,the averaged latitudinal profile of current density peaks at the magnetic equator,with a mean peak value of 27 mA·m^(-1).This amplitude seems smaller than the previous results derived from the CHAMP and Swarm missions,which should be related to the different solar flux levels for the considered periods and local time.The current is narrow with the half-maximum width of about 4°in latitude.The ratio of the peak current density between the main EEJ and its sideband is about 2.7.The considered events consist of both eastward and westward EEJ events,with proportions of 83%and 17%,respectively.This is slightly different from the earlier results derived from the CHAMP satellite,which is related to the relatively lower occurrence rate of westward EEJ at 14∶00 LT.The dependences of the eastward EEJ on longitude,season,and solar activity level are also checked.The averaged EEJ peak current density shows a prominent longitudinal wave number 4 pattern,which should be attributed to the non-migrating tides originated from the lower atmosphere.The EEJ peak current density exhibits a clear dependence on season,showing larger amplitudes in equinox seasons and smaller values for solstice seasons.During the considered period,the EEJ peak current density increases for P_(10.7) index ranging from 68 to 77 sfu.

关 键 词：赤道电集流 张衡一号电磁卫星 地磁观测 峰值电流密度 

分 类 号：P352[天文地球—空间物理学]