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

Earth and Planetary physics 2024年第1期8卷 184-203页

作者： Gonzalo Cucho-Padin Hyunju Connor Jaewoong Jung Brian Walsh David G.Sibeck space Weather Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Department of physics The Catholic University of AmericaWashingtonDCUSA Geospace physics Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Astronomy Department University of Maryland College ParkCollege ParkMDUSA center for space physics Department of Mechanical EngineeringBoston UniversityBostonMAUSA

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 *** 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 *** 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 *** 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 ***-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 *** 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 *** 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 *** results show that 3.D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray ***,our proposed methodology shows that the accuracy of both three-dimensional(3.D)estimation and the magnetopause standoff distance calculation hi

关键词： magnetopause soft X-ray tomography

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An approximate Kerr-Newman-like metric endowed with a magnetic dipole and mass quadrupole

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Communications in Theoretical physics 2024年第8期76卷 124-138页

作者： Francisco Frutos-Alfaro space Research center and School of physics University of Costa RicaSan PedroSan JoseCosta Rica

Approximate all-terrain spacetimes for astrophysical applications are presented. The metrics possess five relativistic multipole moments, namely, mass, rotation, mass quadrupole, charge,and magnetic dipole moment. All these spacetimes approximately satisfy the Einstein-Maxwell field equations. The first metric is generated using the Hoenselaers-Perjés method from given relativistic multipoles. The second metric is a perturbation of the Kerr-Newman metric, which makes it a relevant approximation for astrophysical calculations. The last metric is an extension of the Hartle-Thorne metric that is important for obtaining internal models of compact objects perturbatively. The electromagnetic field is calculated using Cartan forms for locally non-rotating observers. These spacetimes are relevant for inferring properties of compact objects from astrophysical observations. Furthermore, the numerical implementations of these metrics are straightforward, making them versatile for simulating potential astrophysical applications.

关键词： Gravitation Einstein-Maxwell equations Compact objects

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Fast compressed sensing spectral measurement with adaptive gradient multiscale resolution

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Chinese physics B 2024年第2期33卷 298-304页

作者：蓝若明刘雪峰李天平白成杰 School of physics and Electronics Shandong Normal UniversityJinan 250014China Key Laboratory of Electronics and Information Technology for space Systems National Space Science CenterChinese Academy of SciencesBeijing 100190China

We propose a fast,adaptive multiscale resolution spectral measurement method based on compressed *** method can apply variable measurement resolution over the entire spectral range to reduce the measurement time by over 75%compared to a global high-resolution *** the characteristics of the human retina system,the resolution distribution follows the principle of gradually *** system allows the spectral peaks of interest to be captured dynamically or to be specified a priori by a *** system was tested by measuring single and dual spectral peaks,and the results of spectral peaks are consistent with those of global high-resolution measurements.

关键词： spectrometer compressed sensing adaptive gradient multiscale resolution fast measurement

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Explaining the dynamics of the sub-relativistic electron third belt in the Earth's radiation belts by using medium Earth orbit satellite observations

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Earth and Planetary physics 2024年第5期8卷 762-775页

作者： JiaLi Chen Hong Zou YuGuang Ye Institute of space physics and Applied Technology Peking University

The Earth's electron radiation belts typically exhibit a two-belt structure. However, observations from the Van Allen Probes revealed the existence of a three-belt structure. This structure consists of an inner belt, a slot region, a remnant belt, a “second slot,” and a new outer belt(or the “third belt”). The formation of the structure involves both the partial loss of the original outer belts and the formation of the third belts. These processes are likely associated with radial diffusion induced by ultra-low-frequency(ULF) waves. In this study, we mainly analyzed electron flux data from medium Earth orbit(MEO) navigation satellites M17–M19 to supplement the observational evidence for the sub-relativistic electron(～100–500 keV) three-belt structure. Evidence of substorm injections and ULF waves during the three-belt event was identified, suggesting they played significant roles in the formation and evolution of the third *** injections may introduce new electron populations to the third belt, whereas ULF waves may influence the evolution of the third belt through radial diffusion. Toward the end of the three-belt event, the compression of the magnetosphere by shocks may lead to the dropout of the third belt because of the magnetopause shadowing effect and outward radial diffusion, ultimately disrupting the three-belt structure. This study provides more evidence for the presence of a sub-relativistic electron three-belt structure and offers an analysis of the evolutionary mechanisms of the third belt, which may contribute to a comprehensive understanding of the electron three-belt structure in the radiation belts.

关键词： third belt sub-relativistic electrons three-belt structure radiation belts magnetic storms and substorms wave–particle interactions

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Hybrid-Vlasov simulation of soft X-ray emissions at the Earth’s dayside magnetospheric boundaries

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Earth and Planetary physics 2024年第1期8卷 70-88页

作者： M.Grandin H.K.Connor S.Hoilijoki M.Battarbee Y.Pfau-Kempf U.Ganse K.Papadakis M.Palmroth Department of physics University of HelsinkiHelsinkiFinland NASA Goddard space Flight center GreenbeltMD20771USA space and Earth Observation Centre Finnish Meteorological InstituteHelsinkiFinland

Solar wind charge exchange produces emissions in the soft X-ray energy range which can enable the study of near-Earth space regions such as the magnetopause,the magnetosheath and the polar cusps by remote sensing *** Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)and Lunar Environment heliospheric X-ray Imager(LEXI)missions aim to obtain soft Xray images of near-Earth space thanks to their Soft X-ray Imager(SXI)*** earlier modeling works have already simulated soft X-ray images as might be obtained by SMILE SXI during its mission,the numerical models used so far are all based on the magnetohydrodynamics description of the space *** investigate the possible signatures of ion-kinetic-scale processes in soft Xray images,we use for the first time a global hybrid-Vlasov simulation of the geospace from the Vlasiator *** simulation is driven by fast and tenuous solar wind conditions and purely southward interplanetary magnetic *** first produce global X-ray images of the dayside near-Earth space by placing a virtual imaging satellite at two different locations,providing meridional and equatorial *** then analyze regional features present in the images and show that they correspond to signatures in soft X-ray emissions of mirrormode wave structures in the magnetosheath and flux transfer events(FTEs)at the *** results suggest that,although the time scales associated with the motion of those transient phenomena will likely be significantly smaller than the integration time of the SMILE and LEXI imagers,mirror-mode structures and FTEs can cumulatively produce detectable signatures in the soft X-ray *** instance,a local increase by 3.%in the proton density at the dayside magnetopause resulting from the transit of multiple FTEs leads to a 12%enhancement in the line-of-sight-and time-integrated soft X-ray emissivity originating from this ***,a proton density increase by 14%in the magnetosheath

关键词： magnetosphere magnetosheath numerical simulation SMILE LEXI soft X-ray emissions hybrid-Vlasov model polar cusp flux transfer events mirror-mode waves

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Origins of perturbations in dayside equatorial ground magnetograms

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Earth and Planetary physics 2024年第1期8卷 215-221页

作者： Syau-Yun W.Hsieh David G.Sibeck The Johns Hopkins University Applied physics Laboratory LaurelMarylandUSA NASA Goddard space Flight center GreenbeltMarylandUSA

To determine the cause(s)of perturbations seen in dayside equatorial ground magnetograms,we conducted a systematic survey of simultaneous ground-based and geosynchronous satellite-based observations during the 90-day period from December 1,2020 to February 28,*** examined Huancayo ground magnetometer observations from 14:00:00 to 20:00:00 UT each day,during which Huancayo passed through local *** those data we chose perturbation events selected on the basis of large(>20 nT)event amplitude and classified the selected events as responding primarily to solar wind pressure,or to variations in the north/south component of the interplanetary magnetic field(IMF Bz),or perhaps in part to *** results show that an equivalent number of events were identified for each model during this 90-day *** in the lagged solar wind dynamic pressure routinely correspond to nearly simultaneous sudden impulses recorded at both geosynchronous orbit and on the *** in IMF Bz produce erosion signatures at geosynchronous orbit and can correspond to ground events if lag times for reconnection to enhance convection in the magnetosphere are taken into account.

关键词： dayside magnetosphere dayside equatorial ionosphere geosynchronous magnetic field

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Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere

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Earth and Planetary physics 2024年第5期8卷 728-741页

作者： JiaWei Gao ZhaoJin Rong Qi Zhang Anna Mittelholz Chi Zhang Yong Wei Key Laboratory of Earth and Planetary physics Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences Swedish Institute of space physics Department of Earth Sciences center for space physics and Department of Astronomy Boston University

Using over eight years of Mars Atmosphere and Volatile Evolutio N （MAVEN） data,from November 2014 to May 2023.we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity (∣BIMF∣),solar wind dynamic pressure （PSW）,solar extreme ultraviolet flux （EUV）,and Martian seasons （Ls）.Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and *** observed with EUV flux and Lswere weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars *** find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣*** analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration *** findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed ***,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field.

关键词： Martian magnetic field external magnetic field upstream solar wind drivers IMF penetration altitude magnetic field activity indices

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Learning topological defects formation with neural networks in a quantum phase transition

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Communications in Theoretical physics 2024年第5期76卷 68-76页

作者： Han-Qing Shi Hai-Qing Zhang center for Gravitational physics Department of Space ScienceBeihang UniversityBeijing 100191China Peng Huanwu Collaborative center for Research and Education Beihang UniversityBeijing 100191China

Neural networks possess formidable representational power,rendering them invaluable in solving complex quantum many-body *** they excel at analyzing static solutions,nonequilibrium processes,including critical dynamics during a quantum phase transition,pose a greater challenge for neural *** address this,we utilize neural networks and machine learning algorithms to investigate time evolutions,universal statistics,and correlations of topological defects in a one-dimensional transverse-field quantum Ising ***,our analysis involves computing the energy of the system during a quantum phase transition following a linear quench of the transverse magnetic field *** excitation energies satisfy a power-law relation to the quench rate,indicating a proportional relationship between the excitation energy and the kink ***,we establish a universal power-law relationship between the first three cumulants of the kink numbers and the quench rate,indicating a binomial distribution of the ***,the normalized kink-kink correlations are also investigated and it is found that the numerical values are consistent with the analytic formula.

关键词： neural networks machine learning transverse-field quantum Ising model kibble-zurek mechanism

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Acceleration of solar wind particles due to inertial Alfvén waves

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Communications in Theoretical physics 2024年第6期76卷 137-141页

作者： Kiran Batool Imran A Khan M Shamir Abdul Kabir S Ayaz Theoretical physics Department National Centre for PhysicsIslamabad 44000Pakistan Department of space Sciences Institute of Space TechnologyIslamabad 44000Pakistan space and Astrophysics Research Lab(SARL) National Center of GIS and Space Applications(NCGSA)Islamabad 44000Pakistan Salam Chair Department of PhysicsGC University LahoreKatchery RoadLahorePunjab 54000Pakistan Department of space Science and CSPAR University of Alabama in HuntsvilleHuntsvilleAL 35899United States of America

Gaining an understanding of the effects and dynamics of the solar wind is crucial for the study of space weather,Earth's magnetosphere,spacecraft protection,the dynamics of the Solar System,and various other *** show that Alfvén waves effectively transfer energy to resonant *** study demonstrates how inertial Alfvén waves deliver their energy to resonant plasma particles in different solar environments under certain *** analysis shows that inertial Alfvén waves experience more rapid damping with increasing parallel wavenumber,ambient magnetic field strength,and particle number density,coupled with a decrease in *** rate of energy transfer to resonant particles intensifies with higher temperatures and reduced parallel wavenumber and particle number *** with higher initial velocities actively participate in Landau damping,especially in regions with a stronger ambient magnetic field.

关键词： solar wind inertial Alfven waves resonant particles

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Mshpy23.a user-friendly,parameterized model of magnetosheath conditions

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Earth and Planetary physics 2024年第1期8卷 89-104页

作者： Jaewoong Jung Hyunju Connor Andrew Dimmock Steve Sembay Andrew Read Jan Soucek NASA Goddard space Flight center GreenbeltMDUSA Department of Astronomy University of MarylandCollege ParkMDUSA Swedish Institude of space physics UppsalaSweden University of Leicester LeicesterUK Institute of Atmospheric physics Academy of Sciences of the Czech Republic

Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind−Magnetosphere−Ionosphere Link Explorer(SMILE)will observe magnetosheath and its boundary motion in soft X-rays for understanding magnetopause reconnection modes under various solar wind conditions after their respective launches in 2024 and *** conditions,namely,plasma density,velocity,and temperature,are key parameters for predicting and analyzing soft X-ray images from the LEXI and SMILE *** developed a userfriendly model of magnetosheath that parameterizes number density,velocity,temperature,and magnetic field by utilizing the global Magnetohydrodynamics(MHD)model as well as the pre-existing gas-dynamic and analytic *** this parameterized magnetosheath model,scientists can easily reconstruct expected soft X-ray images and utilize them for analysis of observed images of LEXI and SMILE without simulating the complicated global magnetosphere ***,we created an MHD-based magnetosheath model by running a total of 14 OpenGGCM global MHD simulations under 7 solar wind densities(1,5,10,15,20,25,and 3. cm)and 2 interplanetary magnetic field Bz components(±4 nT),and then parameterizing the results in new magnetosheath *** compared the magnetosheath model result with THEMIS statistical data and it showed good agreement with a weighted Pearson correlation coefficient greater than 0.77,especially for plasma density and plasma ***,we compiled a suite of magnetosheath models incorporating previous magnetosheath models(gas-dynamic,analytic),and did two case studies to test the *** MHD-based model was comparable to or better than the previous models while providing self-consistency among the magnetosheath ***,we constructed a tool to calculate a soft X-ray image from any given vantage point,which can support the planning and data analysis of the aforementioned LEXI and SMILE missions.A release of the code has been uploaded to a Git

关键词： magnetosheath python modeling

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