太阳辐射通量对星载朗缪尔探针等离子体密度测量精度的影响  

Solar flux influence on the accuracy of plasma density measured by the spaceborne Langmuir probe

作　　者：朱子渊 熊超[1,2] 郑宇豪 颜蕊 高顺祖 黄宇阳 尹凡 万欣[4,5] ZHU ZiYuan;XIONG Chao;ZHENG YuHao;YAN Rui;GAO ShunZu;HUANG YuYang;YIN Fan;WAN Xin(Department of Space Physics,Electronic Information School,Wuhan University,Wuhan 430072,China;Hubei Luojia Laboratory,Wuhan 430079,China;National Institute of Natural Hazards,the Ministry of Emergency Management,Beijing 100085,China;School of Atmospheric Sciences,SunYat sen University,Zhuhai Guangdong 519082,China;Planetary Environmental and Astrobiological Research Laboratory(PEARL),School of Atmospheric Sciences,Sun Yat-sen University,Zhuhai Guangdong 519082,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 [4]中山大学大气科学学院,广东珠海519082 [5]中山大学宇航科学学院行星环境与宜居性研究实验室,广东珠海519082

出　　处：《地球物理学报》2024年第8期2886-2896,共11页Chinese Journal of Geophysics

基　　金：湖北珞珈实验室专项基金(220100011);国家自然科学基金面上项目(42174191);中欧龙计划项目(59236)联合资助。

摘　　要：本文利用Swarm C卫星和CHAMP卫星搭载的朗缪尔探针测量的电离层就位等离子体密度数据和位于Arecibo及Jicamarca两座非相干散射雷达测量的电子密度数据进行了详细、全面的对比.除此之外,本文还使用了利用GRACE卫星星间测距系统(K-Band Ranging system,KBR)计算得到的星间平均电子密度作为进一步对比.总体上来看,Swarm C、CHAMP和GRACE三颗卫星都与两台地基非相干散射雷达观测数据展现出了良好的线性关系,相关系数分别达到了0.96,0.97,0.96.不同的是,Swarm C卫星与雷达观测间的误差表现出了对太阳辐射通量的依赖,而该依赖关系在CHAMP和GRACE卫星等离子体密度数据中却不明显.结合三颗卫星飞行期间其所处高度及太阳辐射通量的变化,我们认为星载朗缪尔探针的测量结果与探头周围的离子成分有密切关系.比如,在Swarm卫星的数据反演算法中没有考虑离子成分变化对等离子体密度反演精度的影响.在太阳活动低年,较轻的离子(比如H~+)从等离子体层向下扩散到Swarm卫星轨道高度时,其朗缪尔探针就会高估探头周围的等离子体密度.这一影响主要出现在太阳活动低年,且在夜侧要显著大于日侧.与Swarm卫星不同的是,CHAMP卫星的轨道高度随着时间下降(从450 km降至320 km)与太阳辐射通量水平下降的趋势一致,导致CHAMP卫星高度的离子成分变化不明显,其等离子体密度测量误差没有展现出对太阳活动的依赖性.此外,虽然GRACE卫星在2008—2009极低太阳活动年期间,其轨道高度维持在约480 km,但其测量方法并不依赖于卫星周围离子成分的变化,因此其测量结果与雷达观测间的误差也未表现出明显的太阳活动依赖.该对比结果显示了基于GRACE星间测距系统得到的顶部电离层等离子体密度可以为其他基于朗缪尔探针测量的低轨道卫星提供很好的绝对值参考,有助于其他卫星等离子体密度测量的在轨�In this study,we performed a detailed comprehensive comparison of plasma density measured by Langmuir Probes(LP)on board satellites including CHAMP and Swarm C and plasma density measurements by Incoherent Scattering Radar(ISR)in Arecibo and Jicamarca.Besides,we also make a further reference using density data from GRACE K Band Ranging system.Generally,the plasma density datasets of CHAMP,GRACE and Swarm C show a good linear regression with electron density measurement of ISRs.The correlation coefficient of these 3 satellites are 0.96,0.97,0.96.However,in contrast to Grace and CHAMP dataset,the plasma density derived by Swarm LP shows an additional dependence on the solar flux comparing to ISR measurement.Combined with the changes in altitude and solar flux at which the three satellites were located,we suggest that the solar flux dependence of LP-derived plasma density is related to the ion composition change at altitude of satellite orbit,which is unconsidered in Swarm LP processing algorithm.An overestimation appears while more light ions(eg.H+)diffusing down from plasmasphere to Swarm altitude in low solar activity years.This effect mainly occurs during years of low solar activity and is significantly greater on the nightside than that on the dayside.Different from Swarm orbit,height of CHAMP orbit gets down(from 450 km to 320 km)and matches the tendency of solar flux decrease,keeping the ion composition stable on CHAMP orbit and the plasma density measurements haven't shown dependence on solar activity.In addition,although the GRACE satellite maintained its orbital altitude around 480 km during the 2008-20o9 very low solar activity year,its measurements did not depend on the ion composition around the satellite.Therefore the bias between GRACE measurements and ISR observations didn't show a significant solar activity dependence.These results demonstrate that the top ionospheric plasma density based on the GRACE KBR provides a good reference for other LEO satellites based on Langmuir probe measurements,and con

关 键 词：朗缪尔探针 等离子体密度测量 电离层电子密度 

分 类 号：P354[天文地球—空间物理学]