风云四号A星和GOES-13相对论电子观测数据在轨交叉定标及数据融合研究

On-orbit cross-calibration and assimilation for relativistic electron observations from FengYun 4A and GOES-13

地球磁层空间的相对论电子通过内部充放电效应,能够导致在轨航天器彻底失效.由于对这种空间粒子的特性和物理机制仍不清楚,磁层空间相对论电子一直是空间环境探测和空间科学研究的重要对象.开展相关磁层空间环境特性的研究和粒子辐射环境建模等,需要同时使用来自不同卫星、不同探测器的观测数据.消除不同探测器之间的系统偏差,实现不同来源数据的融合,是开展相关研究的必要前提.本文对我国最新的地球同步轨道卫星—风云四号A星(FY-4A)和同类轨道的美国GOES-13卫星相对论电子(>2 MeV)观测数据,开展在轨交叉定标及数据融合研究.本文严格筛选出地磁宁静期(Kp<2)的观测数据,以保证研究对象是被地磁场稳定捕获的辐射带粒子.根据辐射带粒子的物理特性,即3个绝热不变量的基础之上,以Liouville定理为依据,在漂移壳Lm坐标下比较两颗卫星观测到的电子通量,得到两颗卫星相对论电子观测之间的系统偏差.依据该结果,进行数据融合处理,结果表明系统偏差得以很好地消除.通过本项研究工作,得到了国际上重要的两个地球同步轨道相对论电子观测系统之间的偏差,并根据该研究成果,成功实现两个探测系统观测数据之间的融合,为后续的理论和应用研究工作打下了坚实的基础,也为地球同步轨道其他能道高能电子观测数据的在轨交叉定标和数据融合提供了参考方法.

Magnetospheric relativistic electrons can destroy on-orbit spacecrafts completely by internal charging and discharging effects.As the characteristics and physical mechanism of this space particle are still unclear,magnetospheric relativistic electrons have always been an important object of space environment exploration and space science research.For studying the physical mechanisms and developing models relating to magnetospheric relativistic electrons,it is necessary to use the observations from different satellites and detectors at the same time.Eliminating the systematic deviation between different detection systems to assimilate the observations from different sources is essentially required by such researches.In this work,the onorbit cross-calibration and assimilation for relativistic electron(>2 MeV)observations from FengYun 4A and GOES-13 are performed.In this work,only the observations obtained under very quiet geomagnetic conditions(Kp<2)are adopted to ensure that the objects of study are the radiation belt particles,which are stably captured by the geomagnetic field.According to the physical characteristics of the radiation belt particles,that is,the three adiabatic invariants,and based on the Liouville theorem,the phase space density of the stably captured particles is unchanged.In this paper,the relativistic electron flux data of energy>2 MeV and instrument pitch angle are in the east and west direction respectively.If the particles’energy is the same,then their correspondingμvalues are the same,and their particles’directions are the same,then their corresponding J values are the same,and the Liouville theorem can be simplified as the drift shell Lm is the same,the fluxes are the same,and the electron fluxes observed by the two satellites are compared in the drift shell Lm coordinate.The systematic deviation between the two satellites’relativistic electronic observations can be obtained.According to this result,the data assimilation is carried out,and the results show that the system deviation can be removed well.By this research work,the systematic deviation between two important relativistic electron detection systems in geosynchronous orbit is obtained.Based on the obtained systematic deviations,the assimilations for observations from the two detection systems are achieved.This work lays a solid foundation for the follow-up theoretical and applied researches,and also provides the methods for on-orbit cross-calibration and observation assimilation which could be referred to when other electronic observations on geosynchronous orbit are dealt with.