Journal of Geophysical Research: Space Physics最新文献

{"title":"Sayram: A Positivity-Preserving Open Source 3D Radiation Belt Modeling Code","authors":"Peng Peng,&nbsp;Xin Tao,&nbsp;Jay M. Albert,&nbsp;Anthony A. Chan","doi":"10.1029/2025JA033991","DOIUrl":"https://doi.org/10.1029/2025JA033991","url":null,"abstract":"<p>Radiation belt dynamics is typically modeled using a quasilinear diffusion equation. However, standard numerical methods often produce non-physical negative or oscillatory solutions due to cross-diffusion terms. Here, we present Sayram, an open-source 3D radiation belt modeling code that employs a positivity-preserving finite volume method to address this decades-old numerical challenge. Sayram incorporates key physical processes of the radiation belts, including local wave–particle interactions, radial diffusion, and losses due to precipitation and magnetopause shadowing. We validate Sayram using 1D radial diffusion, 2D pitch-angle and momentum diffusion, and a 3D model diffusion problem. Additionally, we apply it to a GEM challenge storm-time radiation belt event, demonstrating consistency with previous results. Compared to other 3D radiation belt codes, Sayram employs an implicit time integration scheme, preserves positivity, and ensures conservation properties. The code is developed in C++ with a highly modular design, allowing for easy adaptation to similar tasks. By making Sayram open source, we aim to provide the radiation belt community with a robust tool to improve radiation belt modeling and forecasting.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511164","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":"Excitation of Storm-Time Pc5 ULF Waves During the 22 July 2009 Storm: Comparison of GOES, Ground Observations, and GEMSIS Coupled Simulation","authors":"Tomotsugu Yamakawa,&nbsp;Kanako Seki,&nbsp;Yoshizumi Miyoshi,&nbsp;Aoi Nakamizo,&nbsp;Kazuhiro Yamamoto","doi":"10.1029/2024JA033647","DOIUrl":"https://doi.org/10.1029/2024JA033647","url":null,"abstract":"<p>Internally driven ULF waves are excited in the premidnight region during the magnetic storm on 22 July 2009. The excitation of ULF waves was investigated based on the Geospace Environment Modeling System for Integrated Studies (GEMSIS) magnetosphere-ionosphere coupled model, GOES spacecrafts, and ground magnetometers. In order to apply the GEMSIS coupled model to the magnetic storm, we included solar wind conditions and loss term of ring current ions due to charge exchange in the model. During the magnetic storm on 22 July 2009, the SYM-H index dropped to nearly −90 nT at 06:00 and 09:00 UT. Poloidal ULF waves were observed by GOES satellites and ground stations from 02:50 to 03:40 UT in the premidnight region. Wave frequency of observed ULF waves was in the range of 1.3–1.8 mHz, and the <i>m</i> number was relatively small, ranging from −3 to −6, propagating westward. ULF waves are also generated in the model from 02:50 UT in the premidnight region. Wave frequency and the <i>m</i> number are similar between the model and observations. Simulation results suggest that the waves are generated by the drift resonance with ring current ions at 50–200 keV and inward gradient of ion PSD contributes to the wave growth. These results indicate that the GEMSIS coupled model is capable of providing the excitation mechanism and global distribution of observed ULF waves.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033647","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511165","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":"The Ionopause at Mars and Its Correlation With Magnetic Topology and Plasma Pressure","authors":"Katerina Stergiopoulou,&nbsp;Beatriz Sánchez-Cano,&nbsp;Mark Lester,&nbsp;Christopher M. Fowler,&nbsp;David J. Andrews,&nbsp;Shaosui Xu,&nbsp;Niklas J. T. Edberg,&nbsp;Simon Joyce,&nbsp;Mats Holmström,&nbsp;Jasper S. Halekas,&nbsp;Dikshita Meggi,&nbsp;Anna K. Turner,&nbsp;Jacob R. Gruesbeck","doi":"10.1029/2024JA032922","DOIUrl":"https://doi.org/10.1029/2024JA032922","url":null,"abstract":"<p>We utilize Mars Atmosphere and Volatile Evolution (MAVEN) observations to investigate the ionopause boundary at Mars, the formation process of which is not yet well described. We focus on the eighth deep dip campaign (DD8), which consists of 50 consecutive orbits, and we develop an automated routine to identify ionopause boundaries in electron density and temperature data. We find ionopause boundaries in 54 out of 100 ionospheric crossings and an average ionopause altitude of 368 km. Having detected the ionopause boundaries, we then examine in detail all the DD8 orbits using complementary observations from several MAVEN instruments. We show examples of two orbits, illustrating how the shapes of the topside ionosphere and ionopause can differ among ionospheric crossings and how the ionopause formation is correlated with changes in magnetic topology and the plasma pressure balance between the ionosphere and the magnetic pile-up region (MPR). We find that 70% of the detected ionopauses are formed where there are changes in magnetic topology, particularly from closed to either open or draped magnetic field lines, and 80% of the boundaries are also formed where the ionospheric plasma pressure becomes equal to the plasma pressure of the MPR. Finally, we confirm that the ionopause boundary is more likely to be formed under high solar wind dynamic pressure conditions.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032922","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511166","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":"The Early-Phase Growth of ULF Waves in the Ion Foreshock Observed in a Hybrid-Vlasov Simulation","authors":"Kun Zhang,&nbsp;Seth Dorfman,&nbsp;Lucile Turc,&nbsp;Urs Ganse,&nbsp;Chen Shi,&nbsp;Hongyang Zhou,&nbsp;Minna Palmroth","doi":"10.1029/2025JA033848","DOIUrl":"https://doi.org/10.1029/2025JA033848","url":null,"abstract":"<p>Large-amplitude ultra-low frequency (ULF) waves in Earth's ion foreshock play a crucial role in the dayside dynamics and solar wind-magnetosphere coupling. This study uses global hybrid-Vlasov simulation results from Vlasiator to investigate the detailed physical processes in the early growth phase of the foreshock ULF waves. Using both spatial and temporal information, the wave phase speed is determined and used to track a specific phase front as the wave evolves. The space-time evolution of the foreshock waves and the backstreaming ions responsible for the wave growth is analyzed and presented in the wave frame for the first time. We employ a state-of-the-art linear dispersion solver, LEOPARD, to solve the wave dispersion relations using the ion distributions and compare the theoretical predictions with the measured wave phase speed and growth rate. The measured phase speed in the spacecraft (or stationary) frame is unexpectedly high at the initial growth stage but later decreases to the predicted level and exhibits an increasing trend over time that aligns with theoretical expectations. The measured and predicted growth rates share the same decreasing trend over time, but the predicted values are consistently lower than the measured growth rate by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>25%. The comparison suggests that the foreshock waves in the Vlasiator simulation are likely generated through the ion-ion right-hand resonant instability, but there are discrepancies with linear theory that are not explained yet and require further investigation.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511167","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":"Predictions for the Shape and Orientation of Earth's Foreshock Radiation Sources","authors":"Iver H. Cairns,&nbsp;Patrick Oppel","doi":"10.1029/2025JA033774","DOIUrl":"https://doi.org/10.1029/2025JA033774","url":null,"abstract":"&lt;p&gt;Radio emission produced in Earth's foreshock is due to the bow shock reflecting some electrons back upstream into the foreshock, where they produce Langmuir waves and radio emissions near the electron plasma frequency &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{p}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and near &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $2{f}_{p}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. Here we predict the source shapes and fluxes of Earth's foreshock radio emissions, with associated implications for other radio sources at multiples of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{p}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. We use an extended model for Earth's foreshock radiation to calculate the electron distributions and the energy flows into Langmuir waves and radiation for specific emission processes. One extension is the addition of linear mode conversion of Langmuir waves into &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{p}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; radiation at density gradients, found to produce &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;≈&lt;/mo&gt;\u0000 &lt;mn&gt;20&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;30&lt;/mn&gt;\u0000 &lt;mi&gt;%&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${approx} 20-30%$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; of the total radio flux near &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{p}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. We produce the first 2D images of Earth's foreshock radio sources for &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033774","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144511238","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":"Effects of Magnetic Shear and Flow Shear on Magnetopause Magnetic Reconnection: Simultaneous Observations From MMS and THEMIS","authors":"Chongle Zhang,&nbsp;Binbin Tang,&nbsp;Wenya Li,&nbsp;Longlong Sang,&nbsp;Huijie Liu,&nbsp;Tongkuai Li,&nbsp;Jiuqi Ma,&nbsp;Wenlong Guo,&nbsp;San Lu,&nbsp;Quanming Lu,&nbsp;Chi Wang","doi":"10.1029/2025JA033778","DOIUrl":"https://doi.org/10.1029/2025JA033778","url":null,"abstract":"<p>Magnetic shear and flow shear form across Earth's magnetopause when shocked solar winds flow around Earth. Previous studies have shown that these two kinds of shears can similarly affect magnetopause reconnection. However, a direct investigation to evaluate their relative importance is lacking. In this study, we focus on simultaneous magnetopause reconnection observed by Magnetospheric Multiscale mission and Time History of Events and Macroscale Interactions during Substorms spacecraft at different magnetopause locations to quantitatively evaluate the magnetic shear and flow shear effects. The overall effect of magnetic shear (the normalized guide field &lt; 1) is limited unless the guide field is sufficient strong to suppress reconnection, whereas the flow shear can significantly affect the observed reconnection outflow speed primarily by introducing non-zero X-line motion. Finally, we propose a novel relationship combining magnetic and flow shear effects by assuming independent X-line drift motion from these two effects, which shows that the X-line drift speed is dominated by the magnetosheath flow, and the suppression of reconnection is more likely to occur under strong guide field conditions. This study deepens our understanding on magnetopause reconnection occurrence and reconnection behaviors in large scales.</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":"144492825","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":"Asymmetric Ionospheric Disturbances Observed by GNSS During the 2017 Typhoon Talim and Doksuri: Origin and Characteristics","authors":"Junxian Fu,&nbsp;Yuichi Otsuka,&nbsp;Hidekatsu Jin","doi":"10.1029/2025JA033854","DOIUrl":"https://doi.org/10.1029/2025JA033854","url":null,"abstract":"<p>The influence of typhoons on the ionosphere has been mentioned in many studies, while the relationship and coupling processes remain elusive. Here, we report findings on concentric ionospheric disturbance (CIDs) during typhoon Talim and Doksuri, using the total electron content (TEC) data derived from the Global Navigation Satellite System (GNSS) network in Taiwan. A fourth-order Butterworth bandpass filter of 8–20 min is applied to the vertical TEC obtained for each pair of satellite and receiver to obtain the perturbation component of TEC. The CIDs were observed with a period of approximately 12 min and a horizontal phase velocity of 141–163 m/s. The CIDs are related to the atmospheric gravity waves (AGWs) generated by upward-moving air in the intense convective regions prompted by typhoons. A pattern of east-west asymmetry, that the TEC variations were significantly more pronounced in the direction opposing the background wind (eastward) compared to the direction aligned with it (westward), was observed in the CIDs. Besides, a model calculation of the electron density variation related to AGWs is used in this study. By the GAIA model, the background wind direction is generally west-northwest. This asymmetry pattern is thought to be the effect of background winds on the vertical wavelength of gravity waves, leading to differences in ionospheric electron density variations in the different directions of gravity wave propagation. The results of model calculations are consistent with the TEC variations from GNSS observations.</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":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033854","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144492817","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":"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}