Journal of Geophysical Research: Space Physics最新文献

{"title":"Electrostatic Charging of Lunar Cavities Governed by the Flow-to-Thermal Speed Ratio: 3D PIC Simulations and a Free-Fall Model","authors":"J. Nakazono, Y. Miyake, W. J. Miloch","doi":"10.1029/2025JA034302","DOIUrl":"https://doi.org/10.1029/2025JA034302","url":null,"abstract":"<p>We use Particle-In-Cell (PIC) simulations to investigate the charging characteristics inside deep cavities on the lunar surface under the solar wind plasma conditions. Specifically, we systematically study the dependence of the cavity bottom potential on plasma flow velocity and cavity aspect ratio. In light of prior results indicating that the charging characteristics are predominantly determined by the cavity aspect ratio, the present analysis employs a rectangular shape for the cavity with a width smaller than the local Debye length. Three flow regimes are then defined according to the ordering among the bulk flow velocity (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mi>flow</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${v}_{mathrm{flow}}$</annotation>\u0000 </semantics></math>) and the ion thermal velocity (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>ti</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${v}_{text{ti}}$</annotation>\u0000 </semantics></math>) and the electron thermal velocity (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>te</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${v}_{text{te}}$</annotation>\u0000 </semantics></math>); low (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>flow</mtext>\u0000 </msub>\u0000 <mo><</mo>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>ti</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${v}_{text{flow}}< {v}_{text{ti}}$</annotation>\u0000 </semantics></math>), medium (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>ti</mtext>\u0000 </msub>\u0000 <mo><</mo>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>flow</mtext>\u0000 </msub>\u0000 <mo><</mo>\u0000 <msub>\u0000 <mi>v</mi>\u0000 <mtext>te</mtext>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${v}_{text{ti}}< {v}_{text{flow}}< {v}_{text{te}}$</annotation>\u0000 </semantics></math>), and high (<span></span><math>\u0000 <semantics>\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034302","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224055","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":"A Global Map of Average Electron Densities in the Magnetosphere of Saturn","authors":"Ulrich Taubenschuss,&nbsp;Ondřej Santolík,&nbsp;David Píša,&nbsp;Masafumi Imai,&nbsp;Georg Fischer,&nbsp;Siyuan Wu,&nbsp;Michiko W. Morooka,&nbsp;William S. Kurth","doi":"10.1029/2025JA034007","DOIUrl":"https://doi.org/10.1029/2025JA034007","url":null,"abstract":"<p>Measurements from the Cassini Radio and Plasma Wave Science (RPWS) experiment obtained during the entire orbital phase of the Cassini mission around Saturn (13.2 years) are processed into a meridional map of plasma densities, comprising the innermost region of the ring ionosphere, the Enceladus plasma torus, and the outer magnetosphere, up to a dipole L-shell of 30. We combine data from RPWS wave observations, such as whistler-mode waves and upper hybrid electrostatic emissions, and from the RPWS Langmuir probe when operated in the proxy mode, providing an estimate for the spacecraft potential. In the region between dipole L-shells of 2.4 and 30, observed electron densities are described by an analytic model that fits two functions, one for the water group ions and one for the protons, to observed densities across latitude on each magnetic field line. The derived electron density profiles are then augmented by a model for the cold core electron temperature as a function of L-shell to obtain a meridional map of the electrostatic potential of the ambipolar electric field. The potential is extrapolated to the inner region of the rings, i.e., to below <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 <mo>=</mo>\u0000 <mn>2.4</mn>\u0000 </mrow>\u0000 <annotation> $L=2.4$</annotation>\u0000 </semantics></math>, to solve for the distribution of electron density in the ring ionosphere. A solution is based on a diffusive equilibrium model for the electrons and two ion species, and on observations from Cassini along the Saturn Orbit Insertion trajectory. A combination of analytic and diffusive equilibrium results finally yields an average global picture for the distribution of electron density in Saturn's magnetosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224066","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 Role of Pedersen Conductance on the Dawn-Dusk Asymmetries in Jupiter's Magnetosphere-Ionosphere System: Model-Data Comparisons","authors":"A. R. Smith,&nbsp;P. A. Delamere,&nbsp;C. E. Spitler,&nbsp;D. S. Ozturk,&nbsp;V. A. Palmer,&nbsp;J. Caggiano,&nbsp;K. Sorathia,&nbsp;A. Sciola,&nbsp;J. Z. Wang,&nbsp;R. J. Wilson,&nbsp;F. Bagenal","doi":"10.1029/2025JA034189","DOIUrl":"https://doi.org/10.1029/2025JA034189","url":null,"abstract":"<p>Jupiter's rapidly rotating magnetosphere, with internal plasma sources such as the volcanic moon Io, provides a unique natural laboratory for studying internally driven planetary magnetospheres. Using the Grid Agnostic Magnetohydrodynamics for Extended Research Applications (GAMERA) model, we simulated Jupiter's magnetosphere with variable ionospheric Pedersen conductances, which is mainly responsible for energy dissipation between the ionosphere and magnetosphere though convection. We chose values ranging from 0.5 to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>6</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $1{0}^{6}$</annotation>\u0000 </semantics></math> mho <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mo>℧</mo>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(mho )$</annotation>\u0000 </semantics></math> to investigate the Pedersen conductance's role in controlling mid-magnetosphere region's dynamics and the closing of magnetosphere-ionosphere currents. Simulated density, temperature, and radial and azimuthal flows in the equator are compared with observations from the Jovian Auroral Distributions Experiment (JADE) on the Juno spacecraft. All simulation cases exhibit dawn-dusk asymmetries, in both the ionosphere and magnetosphere. The 0.5 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>℧</mo>\u0000 </mrow>\u0000 <annotation> $mho $</annotation>\u0000 </semantics></math> case showed the best agreement with JADE observations, while the 1 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>℧</mo>\u0000 </mrow>\u0000 <annotation> $mho $</annotation>\u0000 </semantics></math> case exhibited a magnetic topology more consistent with the auroral observations from the Hubble Space Telescope and Juno. These results enhance our understanding of Jupiter's magnetosphere-ionosphere coupling, provide context for observations, and inform the background parameters of future test particle simulations and data-model comparisons using the GAMERA model.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224101","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":"Dominant Trends in Jupiter's \u0000 \u0000 \u0000 \u0000 \u0000 H\u0000 3\u0000 +\u0000 \u0000 \u0000 \u0000 ${mathbf{H}}_{mathbf{3}}^{mathbf{+}}$\u0000 Northern Aurora: II. Magnetospheric Mapping","authors":"Tom S. Stallard,&nbsp;Katie L. Knowles,&nbsp;Henrik Melin,&nbsp;Ruoyan Wang,&nbsp;Emma M. Thomas,&nbsp;Luke Moore,&nbsp;James O’Donoghue,&nbsp;Rosie E. Johnson,&nbsp;Steve Miller,&nbsp;John C. Coxon","doi":"10.1029/2025JA034076","DOIUrl":"https://doi.org/10.1029/2025JA034076","url":null,"abstract":"<p>Jupiter's auroral regions have previously been defined by broad-scale auroral structures, but these are typically obscured by the wide array of temporal variability observed at timescales between minutes and days, making it difficult to understand the underlying magnetospheric biases driving these brightness differences. Here, we follow on from an initial study of Jupiter's aurora, again utilizing a data set of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math>13,000 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>H</mi>\u0000 <mn>3</mn>\u0000 <mo>+</mo>\u0000 </msubsup>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${mathrm{H}}_{3}^{+}$</annotation>\u0000 </semantics></math> images of Jupiter mapped into latitude, longitude and local time, smoothed over tens of hours of integration and many days of observing. Having removed correlations between brightness and both magnetic field and planetary local time identified in the first study, we examine morphological changes in emission with both planetary and magnetic local time. We reveal that the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>H</mi>\u0000 <mn>3</mn>\u0000 <mo>+</mo>\u0000 </msubsup>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${mathrm{H}}_{3}^{+}$</annotation>\u0000 </semantics></math> main auroral emission is enhanced by a factor of three in the region mapping into the dusk magnetosphere. An additional strong auroral darkening is observed near noon, aligned with previous ultraviolet observations of an auroral discontinuity in this region, though this rotates duskward slightly in magnetic local time, as the ionospheric source mapping to this region moves duskward. The polar aurora contrasts with this strongly, showing brightness enhancement when the auroral pole points toward the dawn and dusk limbs. It also shows that the Dark region is fixed in local time, close to the dawnward edge of the polar region, while the Swirl region appears to match well with predictions from recent MHD models when the magnetic pole points toward dawn, but changes significantly at other magnetic pole directions.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034076","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224099","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":"Comparative Study of Ion and Electron Average Pressure Variation in the Inner Magnetosphere During CIR- and ICME-Driven Storms Observed by the Arase Satellite","authors":"Sandeep Kumar,&nbsp;Y. Miyoshi,&nbsp;Y. Zheng,&nbsp;V. K. Jordanova,&nbsp;L. M. Kistler,&nbsp;K. Yamamoto,&nbsp;T. Hori,&nbsp;C. Jun,&nbsp;K. Asamura,&nbsp;S. Yokota,&nbsp;S. Kasahara,&nbsp;Y. Kazama,&nbsp;S.-Y. Wang,&nbsp;Sunny W. Y. Tam,&nbsp;T.-F. Chang,&nbsp;B.-J. Wang,&nbsp;T. Mitani,&nbsp;T. Takashima,&nbsp;K. Keika,&nbsp;A. Matsuoka,&nbsp;S. Imajo,&nbsp;I. Shinohara","doi":"10.1029/2025JA034182","DOIUrl":"https://doi.org/10.1029/2025JA034182","url":null,"abstract":"<p>Using Arase satellite observations, this study provides a comprehensive statistical analysis of ions (H⁺, He⁺, O⁺) and electron contributions to the total ring current pressure during storms with two different drivers. The results demonstrate the effect of different solar wind drivers on the composition, energy distribution, and spatial characteristics of the ring current. Using 32 CIR- and 30 Interplanetary Coronal Mass Ejection (ICME)-driven storms, we characterize the ring current pressure evolution during the prestorm, main, early-recovery, and late-recovery storm phases as a function of magnetic local time and <i>L</i>-shell. In CIR-driven storms, H⁺ ions are the dominant (∼70%) contributor to the total ring current pressure during main/early recovery phases and increasing to ∼80% during late recovery. In contrast, the O⁺ pressure (<i>E</i> = 20–50 keV) response is significantly stronger in ICME-driven storms contributing ∼40% to the overall pressure during the main/early recovery phases and even dominate (∼53%) in certain MLT sectors. Additionally, ICME-driven storms tend to have peak pressure at lower <i>L</i>-shells (<i>L</i> ≈ 3–4), while CIR-driven storms show pressure peaks at slightly higher <i>L</i>-shells (<i>L</i> ≈ 4–5). Interestingly, electron pressure also plays a notable role in specific MLT sectors, contributing ∼18% (03–09 MLT) during the main phase of CIR-driven storms and ∼11% (21–03 MLT) during ICME-driven storms. The results highlight that the storm time electron pressure plays a crucial role in the ring current buildup. Another noteworthy feature of this study is that Arase's fine-energy resolution and broad coverage enable a detailed investigation of energy-dependent ring current dynamics.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224100","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":"Research on the Impact of Differences in Solar Flare Backgrounds of the Same-Class on Low-Frequency Time Code Time Service Signal","authors":"Zhen Qi,&nbsp;Luxi Huang,&nbsp;Xin Wang,&nbsp;Fan Zhao,&nbsp;Langlang Cheng,&nbsp;Qiang Liu,&nbsp;Yingming Chen,&nbsp;Xiaoqian Ren,&nbsp;Yuping Gao,&nbsp;Ping Feng","doi":"10.1029/2025JA033801","DOIUrl":"https://doi.org/10.1029/2025JA033801","url":null,"abstract":"<p>This study systematically investigates the impact of solar flares on the strength and timing deviation of China's low-frequency time code (BPC) time service signals under different occurrence background conditions based on same-class M1.1-class solar flare event. Seven representative observation cases were selected for the study, with calm day data 2–4 days before and after the cases used for comparison. The duration of solar flares and whether they were accompanied by geomagnetic storms were studied as variables. The study also conducted an in-depth analysis of the changes in BPC during solar flare occurrences using the SYM-H index, Kp index, SuperMAG geomagnetic data, and X-ray flux records from the GOES-16 satellite. The results show that when the X-ray flux reaches its peak, the BPC signals exhibit a sharp decay in strength and fluctuations in timing deviation. The longer the duration of the flare, the greater the disturbance to the signal. In the daytime mid-period, the response of BPC signals in the mid-to-low latitudes to geomagnetic storm background is not significant, as the dominant effect of solar radiation on exciting the D layer of the ionosphere masks the influence of geomagnetic disturbances. This study not only reveals the impact of background differences of same-class solar flares on BPC time service signals and provides strong support for the current understanding of signal-atmosphere interactions but also offers a theoretical basis for the anti-interference design of BPC systems.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224103","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":"Characteristics of Intraseasonal Oscillations During the 2016/2017 Boreal Winter at Mid-Latitudes and Their Relationship With Tropical Convective Activity","authors":"Lingnan Chen,&nbsp;Shaodong Zhang,&nbsp;Kaiming Huang,&nbsp;Chunming Huang,&nbsp;Yun Gong,&nbsp;Zheng Ma","doi":"10.1029/2024JA033665","DOIUrl":"https://doi.org/10.1029/2024JA033665","url":null,"abstract":"<p>Studies of Intraseasonal oscillations (ISOs) in the middle and upper atmosphere at mid- and high latitudes are limited compared to the extensive studies in the tropics. This study reports 20–25-day and 32–44-day oscillations in the zonal wind during the 2016/2017 boreal winter using meteor radar and mesosphere-stratosphere-troposphere (MST) radar observations over Beijing and Wuhan, supplemented by Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalysis data. Both ISOs are observed in the troposphere, stratosphere, and mesosphere, with stronger signals over Beijing than Wuhan; these oscillations have greater amplitudes in the middle and upper atmosphere at mid- and high latitudes, originating in the tropical lower atmosphere and propagating upward over the subtropical regions and poleward in the stratosphere and lower mesosphere. The 20–25-day oscillation possesses a zonal structure of westward wavenumber 1, while the 32–44-day oscillation comprises eastward and westward wavenumber 1 components. Both ISOs modulate the diurnal tide (DT), semidiurnal tide (SDT), and quasi-16-day wave (Q16DW), with the 32–44-day oscillation exhibiting a more pronounced effect. These waves are believed to be involved in the ISO activities during the observational interval. Crucially, strong correlations are found between these ISOs at mid-latitudes and tropical convective activities, evident in Outgoing Longwave Radiation and Sea Surface Temperature (SST) anomalies. Our study highlights the significant role of ISOs in coupling the ocean and atmosphere, the lower and middle/upper atmosphere, and the atmosphere at low and mid-latitudes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224102","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":"Combined Full Wave and Test Particle Simulations of the Io Footprint in the Jovian Aurora","authors":"W. W. Eshetu,&nbsp;R. L. Lysak,&nbsp;A. H. Sulaiman,&nbsp;S. S. Elliott","doi":"10.1029/2025JA034095","DOIUrl":"https://doi.org/10.1029/2025JA034095","url":null,"abstract":"<p>It is known that the perturbation of the co-rotating plasma of Jupiter by Io propagates as Alfvén waves along the magnetic field lines. These waves accelerate electrons, which leads to precipitation and the formation of an auroral footprint on the ionosphere. The Io footprint (IFP) has been observed in Infrared and ultraviolet emissions and known to have a complex morphology. Recently, Lysak et al. (2023, https://doi.org/10.1029/2022ja031180) modeled the propagation of the Alfvén waves in the Io-Jupiter system. This work will present test particle simulations based on these numerical models. By calculating the precipitating electron fluxes integrated with energy and solid angle in the ionosphere, and using it as a proxy for auroral emissions, we successfully reproduced many intricate features of the IFP. In particular, we replicate the main spot, leading spot, sub-dots, asymmetry between northern and southern ionosphere, and asymmetrically bifurcated tail. However, our simulations did not reproduce the stationarity of the sub-dots in the co-rotating frame, as observed by Moirano et al. (2021, https://doi.org/10.1029/2021ja029450). Additionally, we calculated the precipitating electron flux as functions of energy and pitch angle on the main spot, which could serve as input for models that calculate emissions from precipitating electron flux.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034095","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224383","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":"Bridging in Situ Satellite Measurements and Simulations of Magnetic Reconnection Using Recurrent Neural Networks","authors":"Cara L. Waters,&nbsp;Jonathan P. Eastwood,&nbsp;Naïs Fargette,&nbsp;David L. Newman,&nbsp;Martin V. Goldman,&nbsp;Martin O. Archer,&nbsp;Harry C. Lewis,&nbsp;Harley M. Kelly","doi":"10.1029/2025JA034383","DOIUrl":"https://doi.org/10.1029/2025JA034383","url":null,"abstract":"<p>Magnetic reconnection is inherently structured, with distinct spatial regions such as inflows, outflows, and separatrices playing key roles in energy conversion and particle transport. While in situ spacecraft measurements provide detailed local information, determining where a spacecraft lies within the global reconnection geometry remains a major challenge. Proxy-based methods are often ambiguous, while full reconstructions require strong assumptions and are difficult to apply systematically across events. Here, we present a method that bridges these approaches by using machine learning to infer global structural context from local measurements. We first apply <i>k</i>-means clustering to a 2.5-D particle-in-cell simulation to identify six characteristic symmetric reconnection regions. A recurrent neural network (RNN) is then trained on spacecraft-like trajectories through the simulation to classify time series data into these regions. When applied to Magnetospheric Multiscale (MMS) observations of magnetotail reconnection, this method successfully identifies regional transitions, including inflow, outflow, and separatrix crossings, in agreement with previous reconstructions where available. The approach provides a practical, scalable, and automated framework for determining spatial context in reconnection events without requiring full geometric reconstruction, enabling large-scale and efficient statistical studies of reconnection dynamics across multiple events.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034383","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224385","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":"Modeling Regional Electric Field Using EISCAT3D Observations","authors":"Habtamu W. Tesfaw,&nbsp;Heikki Vanhamäki,&nbsp;Ilkka Virtanen,&nbsp;Spencer Hatch,&nbsp;Matt Zettergren,&nbsp;Karl Laundal","doi":"10.1029/2024JA033625","DOIUrl":"https://doi.org/10.1029/2024JA033625","url":null,"abstract":"<p>EISCAT3D, which is in its final stage of construction, will be the next generation incoherent scatter radar (ISR) system to provide the full ion velocity vector across hundreds of kms in vertical and horizontal directions. This presents a tremendous opportunity to study the three-dimensional nature of ionospheric electrodynamics. Here we present a data-driven regional model of the electric field based on the EISCAT3D plasma velocity measurements. The measured F-region ion velocity data are fitted to a regional electric potential produced by a grid of spherical elementary systems. The performance of the model is demonstrated using simulated ionospheric parameters obtained from the GEMINI model. To simulate realistic radar measurement of the ion velocity, error estimates obtained from the <i>e3doubt</i> package are added to the ground-truth GEMINI data. Our model can be used with either multistatic or monostatic measurements of the ion velocity, and it can also integrate ion velocity data from other platforms, such as satellite sensors, into existing ISR measurements. The model captures the ground truth electric field including its complex spatial structure with average percentile differences of about 7%. Most accurate results are achieved with the multistatic data, but the general spatial structure of the electric field can be captured also with monostatic data, if optimal beam patterns and regularization are used. The modeling method is also applied using real monostatic line-of-sight ion velocity data measured by the Poker Flat ISR. The modeled electric field shows reasonably well-behaved variations in latitude and longitude within the radar's field of view.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033625","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224410","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}