Finding the magnetopause location using soft X-ray observations and a statistical inverse method  

作　　者：Gonzalo Cucho-Padin Hyunju Connor Jaewoong Jung Brian Walsh David G.Sibeck 

机构地区：[1]Space Weather Laboratory,NASA Goddard Space Flight Center,Greenbelt,MD,USA [2]Department of Physics,The Catholic University of America,Washington,DC,USA [3]Geospace Physics Laboratory,NASA Goddard Space Flight Center,Greenbelt,MD,USA [4]Astronomy Department,University of Maryland College Park,College Park,MD,USA [5]Center for Space Physics,Department of Mechanical Engineering,Boston University,Boston,MA,USA

出　　处：《Earth and Planetary Physics》2024年第1期184-203,共20页地球与行星物理（英文版）

基　　金：supported by NASA Goddard Space Flight Center through Cooperative Agreement 80NSSC21M0180 to Catholic University;Partnership for Heliophysics and Space Environment Research(PHaSER);the NASA Heliophysics United States Participating Investigator Program under Grant WBS516741.01.24.01.03(DS);support from the NASA grants 80NSSC19K0844,80NSSC20K1670,and 80MSFC20C0019;the NASA GSFC internal fundings(HIF,ISFM,and IRAD)。

摘　　要：Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the magnetosphere.The spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to interpret.Global wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial magnetosphere.Two upcoming missions,ESA/CAS SMILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral atoms.High-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field orientation.This work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth line.To do so,we simulate the magnetosheath structure using the MHD-based OpenGGCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude information.Our results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray images.Also,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation highly depends on the observational point.

关 键 词：MAGNETOPAUSE soft X-ray TOMOGRAPHY 

分 类 号：P353[天文地球—空间物理学]