Journal of Geophysical Research: Space Physics最新文献

{"title":"Responses of the Ionospheric Zonal Currents From Equator to Middle Latitudes During the Intense Geomagnetic Storm on 10–12 May 2024","authors":"Chao Xiong,&nbsp;Yuyang Huang,&nbsp;Fengjue Wang,&nbsp;Hermann Lühr,&nbsp;Yunliang Zhou,&nbsp;Jia Zhu","doi":"10.1029/2025JA033992","DOIUrl":"https://doi.org/10.1029/2025JA033992","url":null,"abstract":"<p>In this study, we performed a detailed analysis of the ionospheric zonal currents from equator to middle latitudes during the recent intense geomagnetic storm on 10–12 May 2024. Magnetic measurements from two ground stations in the America sector as well as those from the Swarm satellites have been used. Extreme intensified eastward and westward EEJ values reaching 300 and −400 mA/m have been observed during the storm main and recovery phases, respectively. Such intense EEJ values have never been observed during the past 11-year flying period of Swarm mission. In addition, the storm responses of zonal currents at low and middle latitudes have been analyzed using the vertical magnetic field component from Swarm. These zonal currents showed quite prominent dependence on magnetic local time. In the noon sector, eastward currents were dominated under both quiet and storm conditions, with slight intensification during the storm. Conversely, the zonal currents in the dawn and dusk sectors displayed abrupt current reversals within 30 min after the storm sudden commencement, characterized by sustained eastward (dawn) and westward (dusk) perturbations persisting for the rest of one and a half days. Most interestingly, two eastward zonal current jets were found located at ±25° magnetic latitudes at the dusk sector and emerged with westward zonal currents at other low and middle latitudes. We speculate that a shear layer of zonal eastward winds is needed at a conjugate altitude to cause the narrow eastward current jets. To our knowledge, this is the first report of such narrow current jets at middle latitudes during storms.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144492862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Daytime Electromagnetic Power in the Topside Ionosphere Radiated From VLF Transmitters During Solar Minimum Period of Cycle 23/24","authors":"Shengyang Huang,&nbsp;Shufan Zhao,&nbsp;Li Liao,&nbsp;Xuan Dong,&nbsp;Hengxin Lu,&nbsp;Xuhui Shen","doi":"10.1029/2025JA033950","DOIUrl":"https://doi.org/10.1029/2025JA033950","url":null,"abstract":"<p>The propagation of Very Low Frequency (VLF) waves from ground-based VLF transmitters worldwide allows them to penetrate the ionosphere and enter the magnetosphere. This interaction drives electron precipitation in the inner radiation belts through resonant interactions. The energy loss of VLF waves penetrating the ionosphere occurs mainly in the lower ionosphere, which is mainly affected by solar shortwave radiation. However, the solar activity affecting the energy of VLF transmitter signals reaching the topside ionosphere has not been sufficiently studied during the solar minimum period. In this paper, we quantify the correlation between the electromagnetic field radiated to the topside ionosphere by different VLF transmitters and solar activity, as well as the energy injected into the topside ionosphere during the daytime, using data from the DEMETER satellite. Our findings demonstrate that both the average daytime radiated electric field and magnetic field above the four VLF transmitters are negatively correlated with solar activity. Furthermore, even during the lower solar activity years, the radiated power in the topside ionosphere from VLF transmitters in the winter of 2008 during the daytime was found to be more than 2.5 times higher than that in the winter of 2004.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144367214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MHD Simulations of Europa's Interaction With Jupiter's Magnetosphere During the Juno Flyby: Electron Beams in the Plasma Wake","authors":"S. Cervantes,&nbsp;J. Saur,&nbsp;S. Duling,&nbsp;J. R. Szalay,&nbsp;S. Schlegel,&nbsp;J. E. P. Connerney,&nbsp;F. Allegrini,&nbsp;S. Bolton","doi":"10.1029/2025JA033825","DOIUrl":"https://doi.org/10.1029/2025JA033825","url":null,"abstract":"<p>In September 2022, the Juno mission performed its only close flyby of Europa and traversed the moon's wake at a minimum distance of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>350 km. Among other findings, the Jovian Auroral Distributions Experiment (JADE) detector onboard the spacecraft discovered intense field-aligned electron beams (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>30–300 eV) downstream of the moon. In this study, we apply a three-dimensional magnetohydrodynamic model to simulate the plasma interaction of Jupiter's magnetosphere with Europa and its atmosphere for the conditions of this flyby, and we specifically focus on the influence of the electron beams on the plasma density and the magnetic field in the moon's space environment. We include these beams in our simulations as sheets of locally enhanced ionization, and we use electron impact ionization rates of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{O}}_{mathrm{2}}$</annotation>\u0000 </semantics></math> derived from JADE electron measurements to characterize the sheets. We compare our results with the magnetic field and the total ion number density measurements from Juno's magnetometer and JADE detector, respectively. Our results show that the beams fill the wake downstream of Europa with newly ionized plasma, and that they generate large variations in the magnetic field which contribute partially to the observed magnetic field. Our study demonstrates that the electron beams are critical factors in shaping Europa's magnetic field and plasma environment, and thus they need to be accounted for in the data analysis of the upcoming JUICE and Europa Clipper missions.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033825","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144367217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lidar Observations of Thermosphere-Ionospheric Ca+ at Mohe (122.3°E, 53.5°N)","authors":"Jing Jiao,&nbsp;Fang Wu,&nbsp;Lifang Du,&nbsp;Guotao Yang,&nbsp;Haoran Zheng,&nbsp;Xiaofei Wu","doi":"10.1029/2025JA033813","DOIUrl":"https://doi.org/10.1029/2025JA033813","url":null,"abstract":"<p>The ionosphere is an open area, affected by solar activity or geomagnetic activity, and affected by the lower atmosphere. Moreover, previous studies believed that metallic iron ions were a necessary condition for the formation of ionospheric irregularities, but so far there are no favorable observations to support it. In this paper, we use a Ca⁺ lidar at Mohe to explore the relationship between metal ions and ionospheric irregularities. The reason for choosing Mohe Station is that this region is at the northernmost point of China and is on the edge of the sub-aurora zone during the peak year of solar activity. Mohe thermosphere and ionosphere Ca⁺ (TICa⁺) is associated with Spread F or may be related with magnetic storms. The TICa⁺ generally occurred before dawn. In addition, the density of main Ca⁺ layer (80–120 km) in the autumn months is low, and the upper TICa⁺ (120–300 km) event density is also low with an order of 10 cm⁻³. However, during magnetic storm periods, the density of TICa⁺ increased with an order of 100 cm⁻³, which is comparable to or higher than summer results.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144339599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial Distribution and Geomagnetic Dependence of Radiation Belt Electron Reversed Energy Spectrum","authors":"Jiaming Li,&nbsp;Yuequn Lou,&nbsp;Xudong Gu,&nbsp;Binbin Ni,&nbsp;Qi Zhu,&nbsp;Xin Ma,&nbsp;Shuqin Chen","doi":"10.1029/2025JA033738","DOIUrl":"https://doi.org/10.1029/2025JA033738","url":null,"abstract":"<p>Using high-quality electron measurements from Van Allen Probes during October 2013 and March 2019, this study investigates the spatial distribution and geomagnetic dependence of the electron reversed energy spectrum in the Earth's radiation belts. The reversed energy spectrum is primarily observed within the L-shell range of ∼2.6–5.2, with peak occurrence rates reaching ∼50% at <i>L</i> = ∼4. Occurrence rates are higher in the post-noon to midnight sectors and lower on the pre-dawn side. In terms of magnetic latitude (MLAT), the spectrum spans ∼−20°–20°, exhibiting south-north asymmetry, particularly in the noon and night regions. The characteristic energies defining the spectrum correspond to the flux minimum (Ev) and maximum (Ep), which typically range from ∼100 keV to ∼1 MeV and hundreds of keV–∼2 MeV, respectively, with both Ev and Ep decreasing as <i>L</i> increases. The spectrum is more frequently observed during geomagnetically quiet periods, with maximum occurrence rates exceeding 50%. However, as geomagnetic activity intensifies, the occurrence rates decrease significantly, and the favorable region contracts toward lower L-shells. Analysis of geomagnetic indices shows that the reversed energy spectrum is more strongly affected by the Dst index than the auroral electrojet (AE) index. This could suggest a more substantial influence of geomagnetic storms than the substorm activity on suppressing the electron reversed energy spectrum. These results improve our understanding of how radiation belt electron dynamics respond to geomagnetic disturbances, emphasizing the interplay between storms, substorms, and wave-particle interactions in shaping the evolution of the reversed electron energy spectrum.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144339372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interplanetary Hydrogen Observations of the Emirates Ultraviolet Spectrometer Onboard the Emirates Mars Mission","authors":"R. Susarla,&nbsp;J. Deighan,&nbsp;M. S. Chaffin,&nbsp;E. Quemerais,&nbsp;S. Jain,&nbsp;R. J. Lillis,&nbsp;G. Holsclaw,&nbsp;K. Chirakkil,&nbsp;D. Brain,&nbsp;Ed. Thiemann,&nbsp;F. Eparvier,&nbsp;F. Lootah,&nbsp;M. Gacesa,&nbsp;M. O. Fillingim,&nbsp;J. S. Evans,&nbsp;H. AlMazmi,&nbsp;H. AlMatroushi,&nbsp;M. R. El-Maarry","doi":"10.1029/2025JA033903","DOIUrl":"https://doi.org/10.1029/2025JA033903","url":null,"abstract":"<p>The Emirates Mars Ultraviolet Spectrometer (EMUS) aboard the Emirates Mars Mission (EMM) has been studying backscattered interplanetary hydrogen (interplanetary hydrogen (IPH)) Lyman emissions with dedicated observation strategies viz., U-OS3b and U-OS4b. These observation techniques involve looking away from Mars from the EMM's orbit. U-OS3b provides broader coverage of the Martian sky, while U-OS4b is designed to achieve high signal-to-noise measurements. Here we present analysis of the interplanetary hydrogen emission distribution across the sky, particularly at the Lyman-<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>α</mi>\u0000 </mrow>\u0000 <annotation> $alpha $</annotation>\u0000 </semantics></math> and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>β</mi>\u0000 </mrow>\u0000 <annotation> $beta $</annotation>\u0000 </semantics></math> emission wavelengths. EMUS observes a well-known reduction in the brightness of interplanetary hydrogen as the observation angle increases across the sky from the hydrogen bulk flow upwind direction. Our modeled emission intensities indicate that when Mars is around aphelion, the observed emissions are dominated by IPH rather than Martian exospheric hydrogen. Our modeled intensities for H Ly-<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>α</mi>\u0000 </mrow>\u0000 <annotation> $alpha $</annotation>\u0000 </semantics></math> emission are smaller by a factor of 1.6 compared to the observations, and they are consistent with the observations for H Ly-<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>β</mi>\u0000 </mrow>\u0000 <annotation> $beta $</annotation>\u0000 </semantics></math> emission. The H Ly-<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>α</mi>\u0000 </mrow>\u0000 <annotation> $alpha $</annotation>\u0000 </semantics></math> intensities measured by the Imaging Ultraviolet Spectrograph (IUVS) on board the Mars Atmosphere and Volatile EvolutioN mission were found to be 45% lower than those from EMUS measurements, likely owing to differences in the instruments' calibration factors. During the observation period, differences in the measured intensities between the Solar Wind ANisotropy (SWAN) instrument aboard the Solar and Heliospheric Observatory and EMUS were also found to vary. These discrepancies can be attributed not only to instrumental factors but also to the relative positions of Earth and Mars.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033903","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parametric Regimes of Thin Current Sheets in Planetary Magnetospheres and Solar Wind","authors":"David S. Tonoian,&nbsp;Xiao-Jia Zhang,&nbsp;Anton Artemyev,&nbsp;Qianli Ma,&nbsp;Robert W. Ebert,&nbsp;Frederic Allegrini","doi":"10.1029/2025JA033942","DOIUrl":"https://doi.org/10.1029/2025JA033942","url":null,"abstract":"<p>Current sheets are quasi-1D layers of strong current density, which play a crucial role in storing magnetic field energy and subsequently releasing it through charged particle acceleration and plasma heating. They are observed in planetary magnetospheres and solar wind flows, where they are also known as solar wind discontinuities. Despite significant variations in plasma parameters across different magnetospheres and the solar wind, current sheet configurations can remain fundamentally similar. In this study, we analyze current sheets observed in various regions, including the near-Earth (within 30 Earth radii) and distant (50–200 Earth radii) magnetotail, Earth's dayside and nightside magnetosheath, the near-Earth solar wind, and Martian and Jovian magnetotails. We examine three key plasma parameters: the plasma beta (ratio of plasma to magnetic pressure), the Alfvénic Mach number (ratio of plasma bulk flow speed to Alfvén speed in the current sheet reference frame), and the ion to electron temperature ratio. Additionally, we investigate the kinetic, thermal, and magnetic field energy densities. Our cross-system analysis demonstrates that the same current sheet configuration can exist across a very wide parametric space spanning multiple orders of magnitude. We also highlight the distinct plasma environments of the Martian and Jovian magnetotails, characterized by large populations of heavy ions, emphasizing their significance in comparative magnetospheric studies.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Joint Observations of Plasmapause Surface Waves and Giant Undulations in the Electron Aurora","authors":"Xin-Yu Ai,&nbsp;Jie Ren,&nbsp;Qiu-Gang Zong,&nbsp;Yi-Xin Hao,&nbsp;Zi-Jian Feng,&nbsp;Ting-Yan Xiang","doi":"10.1029/2025JA033878","DOIUrl":"https://doi.org/10.1029/2025JA033878","url":null,"abstract":"<p>After the onset of an intense storm-time substorm (the minimum AL <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>−2,400 nT) on 8 September 2017, both Van Allen Probes and ground stations observed large-amplitude plasmasphere surface waves (PSWs) in the duskside, which lasted for more than 3 hr. Van Allen Probe B observations show that PSWs caused spatial and temporal modulations of sub-keV electrons with bidirectional pitch-angle distributions and higher-frequency plasma waves outside the plasmapause at the L-shells of 3.5–5.5. These kinetic-scale waves include kinetic Alfvén waves (KAWs) with frequencies below 10 Hz, time domain structures with frequencies from tens to hundreds of Hz, and electrostatic electron cyclotron harmonic waves (ECHs) with frequencies of tens of kHz. The bidirectional pitch angles and flux enhancement of sub-keV electrons indicate that they originate from the ionospheric outflow and are susceptible to pitch-angle scattering by kinetic-scale plasma waves. Following Probe B with a time delay of about 2 hr, Probe A observed PSW-associated ULF waves inside the plasmasphere at L-shells of 5–6, which can cause the drift-bounce resonance of cold (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&lt;</mo>\u0000 </mrow>\u0000 <annotation> ${&lt; } $</annotation>\u0000 </semantics></math>50 eV) electrons. Corresponding to the duration and location of PSWs, DMSP-F17 observed intense sub-keV electron precipitation and weak ion precipitation, which coincides with the observations of giant undulations (GUs) in the electron aurora. These space-ground joint observations provide new sights into understanding the complicated middle processes between magnetospheric PSWs and ionospheric GUs.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144332000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bipolar Reversal in the Off-Diagonal Ion Pressure Term in Collisionless Magnetic Reconnection","authors":"Kailai Wang,&nbsp;Lei Dai,&nbsp;Shan Wang,&nbsp;Yong Ren,&nbsp;Minghui Zhu,&nbsp;Chi Wang,&nbsp;Benoit Lavraud,&nbsp;C. Philippe Escoubet,&nbsp;James L. Burch","doi":"10.1029/2025JA034185","DOIUrl":"https://doi.org/10.1029/2025JA034185","url":null,"abstract":"<p>Magnetic reconnection is a fundamental process that converts magnetic energy into particle energy, with wide applications in space plasmas. A key manifestation of this energy conversion is the acceleration of fast ion outflows. However, ion processes and their associated signatures in energy conversion remains only partially understood in collisionless magnetic reconnection. In this study, we utilize statistical analyses of in-situ observations and particle-in-cell (PIC) simulations to identify a distinct signature in the off-diagonal component of the ion pressure tensor. This signature displays a bipolar reversal that correlates with ion outflows across the reconnection X-line. The bipolar signal originates from distorted ion velocity distributions during acceleration. These signals are confirmed by statistical in-situ evidence for the first time and captured by PIC simulations. PIC simulations further indicate the peak of the off-diagonal ion pressure is near the magnetic pileup region associated with the ion outflow. Trajectories of ions in the distorted velocity distributions are traced within the PIC simulations. Ions in the distorted distributions undergo partial cyclotron motion around the reconnected magnetic field (<i>B</i>_<i>z</i>) and acceleration by the reconnection electric fields. The observation of bipolar reversal in the off-diagonal ion pressure term indicate its spatial gradient, which could contribute to supporting ion-scale reconnection electric fields. These findings provide new insights into the fundamental features of energy conversion in collisionless magnetic reconnection.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining the Subsolar Magnetopause Position Using CMEM","authors":"S. J. Wharton,&nbsp;J. A. Carter,&nbsp;S. Sembay,&nbsp;Y. Soobiah,&nbsp;A. M. Read,&nbsp;T. R. Sun","doi":"10.1029/2025JA033837","DOIUrl":"https://doi.org/10.1029/2025JA033837","url":null,"abstract":"<p>The wide field-of-view soft X-ray imager on the upcoming SMILE mission will revolutionize our understanding of magnetopause dynamics from observations of SWCX in the magnetosheath. Inferring the position of the 3D magnetopause boundary in the 2D images is challenging, but several methods have been developed to do this. One method generates images through a 3D emissivity model and adapts its parameters to achieve the best fit with real images. The subsolar magnetopause position is extracted from the fitted model. We show that the Wharton et al. (2025, https://doi.org/10.1029/2024ja033307), cusp and magnetosheath emissivity model can be used successfully for this purpose in a wide range of scenarios. The method works when varying the image resolution, the orientation of the imager around its pointing axis, the aim point of the imager, and for a range of solar wind densities. We also show the method works from a range of orbital positions with realistically constrained viewing geometries. Finally, we tested the method on ensembles of realistic X-ray counts images which contain noise and instrumental contributions, allowing us to determine the uncertainty in the subsolar magnetopause distance over a wide range of solar wind densities. We found that CMEM accurately determined the subsolar magnetopause distance whenever it lies within the field-of-view and the signal-to-noise ratio was sufficient to observe the magnetosheath. The standard deviation of the subsolar magnetopause distance was less than 0.25 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>R</mi>\u0000 <mi>E</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{R}}_{E}$</annotation>\u0000 </semantics></math> whenever the subsolar magnetopause was visible.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033837","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144323573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}