Journal of Geophysical Research: Space Physics最新文献

{"title":"Plasma Refilling of the Lunar Wake: Plasma-Vacuum Interactions, Electrostatic Shocks, and Electromagnetic Instabilities","authors":"Xin An,&nbsp;Vassilis Angelopoulos,&nbsp;Terry Z. Liu,&nbsp;Anton Artemyev,&nbsp;Andrew R. Poppe,&nbsp;Donglai Ma","doi":"10.1029/2025JA034205","DOIUrl":"https://doi.org/10.1029/2025JA034205","url":null,"abstract":"<p>A plasma void forms downstream of the Moon when the solar wind impacts the lunar surface. This void gradually refills as the solar wind passes by, forming the lunar wake. We investigate this refilling process using a fully kinetic particle-in-cell (PIC) simulation. The early stage of refilling follows plasma-vacuum interaction theory, characterized by exponential decay of plasma density into the wake, along with ion acceleration and cooling in the expansion direction. Our PIC simulation confirms these theoretical predictions. In the next stage of the refilling process, the counter-streaming supersonic ion beams collide, generating Debye-scale electrostatic shocks at the wake's center. These shocks decelerate and thermalize the ion beams while heating electrons into flat-top velocity distributions along magnetic field lines. Additionally, fast magnetosonic waves undergo convective growth via anomalous cyclotron resonance as they co-propagate with temperature-anisotropic ion beams toward the wake's center. Electromagnetic ion cyclotron waves may also be excited through normal cyclotron resonance, counter-propagating with these anisotropic ion beams. Our findings provide new insights into the kinetic aspects of lunar wake refilling and may enhance interpretation of spacecraft observations.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581829","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":"Debye-Scale Electrostatic Waves Across Quasi-Perpendicular Shocks","authors":"Ahmad Lalti,&nbsp;Yuri V. Khotyaintsev,&nbsp;Daniel B. Graham,&nbsp;Andris Vaivads","doi":"10.1029/2025JA033881","DOIUrl":"https://doi.org/10.1029/2025JA033881","url":null,"abstract":"&lt;p&gt;The evolution of the properties of short-scale electrostatic waves across collisionless shocks remains an open question. We use a method based on the interferometry of the electric field measured aboard the magnetospheric multiscale spacecraft to analyze the evolution of the properties of electrostatic waves across four quasi-perpendicular shocks, with &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;1.4&lt;/mn&gt;\u0000 &lt;mo&gt;≤&lt;/mo&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;mi&gt;A&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;≤&lt;/mo&gt;\u0000 &lt;mn&gt;4.2&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $1.4le {M}_{A}le 4.2$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;66&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mo&gt;≤&lt;/mo&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;B&lt;/mi&gt;\u0000 &lt;mi&gt;n&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;≤&lt;/mo&gt;\u0000 &lt;mn&gt;87&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $66{}^{circ}le {theta }_{Bn}le 87{}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. Most of the analyzed wave bursts across all four shocks have a frequency in the plasma frame &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;mrow&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;mi&gt;l&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{pl}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; lower than the ion 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;mrow&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;mi&gt;i&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{pi}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and a wavelength on the order of 20 Debye lengths &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;λ&lt;/mi&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${lambda }_{D}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. Their direction of propagation is predominantly field-aligned upstream and downstream of the bow shock, while it is highly oblique within the shock transition region, which might indicate a shift","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033881","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581827","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":"Longitudinal Variations in the Ionospheric Disturbances: Insights From the May 2024 Super Storm","authors":"Usman Ahmad,&nbsp;Waqar Younas,&nbsp;Majid Khan,&nbsp;M. M. Abbasi","doi":"10.1029/2025JA033981","DOIUrl":"https://doi.org/10.1029/2025JA033981","url":null,"abstract":"&lt;p&gt;We present an analysis of the super storm event that occurred on 10–11 May, 2024, focusing on ionospheric and magnetic signatures across different longitudinal sectors using space-borne and ground-based data. On 10 May, a strong positive ionospheric storm was observed in the southern hemisphere (winter), while northern hemisphere (summer) experienced negative storm effects. The most pronounced positive storm effects emerged in the American-Pacific sector during local evening hours, followed by Asia and Africa on 11 May. A significant drop in the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;mo&gt;/&lt;/mo&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $O/{N}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; ratio was observed in the northern hemisphere, which likely contributed to the negative ionospheric storm. This depletion appears to be driven by strong thermospheric winds induced by the increase auroral electrojet currents, as indicated by the SME index. The SWARM satellite data revealed numerous plasma bubbles, predominantly at equatorial ionization anomaly (EIA) crests, with some extending up to &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;40&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $40{}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; latitude. Our analysis suggests that equatorial plasma bubbles (EPBs) following the initial phase of the storm were enhanced by prompt penetration electric fields (PPEFs) and strong electrojet currents, while those in recovery phase were primarily driven by disturbance dynamo electric fields (DDEFs). Additionally, in the America and Africa regions, the magnitude 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;D&lt;/mi&gt;\u0000 &lt;mi&gt;dyn&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${D}_{mathit{dyn}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; was higher than in the Asia and Pacific sectors, indicating strong neutral winds that contribute to the decrease in &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;mo&gt;/&lt;/mo&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $O/{N}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; ratio. Conversely, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $D{P}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581828","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":"Variation of Mesosphere Ozone and Related Constituents During Solar Eclipse on 21 June 2020 Based on WACCM-X Simulations","authors":"Mingming Zhan,&nbsp;Jingyuan Li,&nbsp;Jianyong Lu,&nbsp;Shuai Fu,&nbsp;Haiwen Yao,&nbsp;Ningtao Huang,&nbsp;Meng Sun,&nbsp;Guanchun Wei,&nbsp;Shiping Xiong,&nbsp;Ming Wang,&nbsp;Zheng Li,&nbsp;Hua Zhang,&nbsp;Xinhao Chen","doi":"10.1029/2024JA033534","DOIUrl":"https://doi.org/10.1029/2024JA033534","url":null,"abstract":"<p>The Whole Atmosphere Climate Community Model is utilized to simulate the complete process of variation in ozone and related constituent concentrations within the height range of 47–79 km (1–0.01 hPa) in the mesosphere during the annular solar eclipse on 21 June 2020. The simulated ozone vertical profile closely matches the Microwave Limb Sounder observation. Simulation results show that the largest average ozone concentration increase occurs at 66 km (0.07547 hPa), reaching 18.4%. Ozone concentration at this altitude increases by 96.0% after the eclipse obscuration reaches its maximum. The ozone increased region closely follows the trajectory of the eclipse obscuration, although its spatial extent is slightly smaller. Only regions experiencing more than 30% solar obscuration exhibited ozone increases exceeding 10%. This study quantitatively analyzes the relative contributions of different factors to ozone variations during the solar eclipse. Ozone variations are primarily driven using chemical processes rather than dynamic transport. The key chemical pathways involve ozone production through the three-body recombination (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mo>+</mo>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 <mo>+</mo>\u0000 <mi>M</mi>\u0000 <mo>=</mo>\u0000 <msub>\u0000 <mi>O</mi>\u0000 <mn>3</mn>\u0000 </msub>\u0000 <mo>+</mo>\u0000 <mi>M</mi>\u0000 </mrow>\u0000 <annotation> $mathrm{O}+{mathrm{O}}_{2}+mathrm{M}={mathrm{O}}_{3}+mathrm{M}$</annotation>\u0000 </semantics></math>), ozone photolysis, and the H-ozone reaction. Reduced solar radiation suppresses photolysis more effectively than it limits ozone production, resulting in a net increase in O₃ concentration. Meanwhile, the decreased production of H further weakens the destruction of ozone. Single-point analysis reveals that at the eclipse central location, the change in the ozone variation rate from the three-body recombination and photolysis accounts for 75.2% of the O₃ chemical variation rate change collectively. The H-ozone reaction accounts for 24.7% of the ozone chemical variation.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581973","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":"A Characterization of Reconnection at the Far Flanks of the Earth's Magnetopause","authors":"K. M. Sullivan,&nbsp;S. A. Fuselier,&nbsp;E. Choi,&nbsp;S. K. Vines,&nbsp;S. M. Petrinec,&nbsp;K. J. Trattner,&nbsp;J. L. Burch,&nbsp;D. J. Gershman,&nbsp;D. K. V. Radhakrishnan","doi":"10.1029/2025JA034017","DOIUrl":"https://doi.org/10.1029/2025JA034017","url":null,"abstract":"<p>Magnetospheric Multiscale (MMS) mission observations previously indicated that magnetic reconnection, under certain circumstances, is prevalent at low latitudes at and past the Earth's terminator. This insight revealed a new regime to study reconnection. This study investigates some close encounters between MMS satellites and reconnection x-lines at the far-flank magnetopause. This study finds that magnetic reconnection on the far flanks is typically anti-parallel, and that the plasma bulk flow in the magnetosheath is nearly parallel to the plane of the reconnection x-line and perpendicular to the outflow direction. An LMN coordinate transform showed that L, the dominant direction of the reconnection exhaust outflow, is in the positive Z (Geocentric Solar Magnetospheric) direction. Finally, observations along the far flanks serve as reasonable input conditions for numerical simulations.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563078","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":"Studying the Evolution of ICMEs in the Heliosphere Through Multipoint Observations","authors":"Zhiyong Zhang,&nbsp;Chenglong Shen,&nbsp;Yutian Chi,&nbsp;Dongwei Mao,&nbsp;Junyan Liu,&nbsp;Mengjiao Xu,&nbsp;Zhihui Zhong,&nbsp;Jingyu Luo,&nbsp;Can Wang,&nbsp;Yuming Wang","doi":"10.1029/2025JA034094","DOIUrl":"https://doi.org/10.1029/2025JA034094","url":null,"abstract":"&lt;p&gt;Interplanetary coronal mass ejections (ICMEs) are the main cause of severe space weather in near-Earth space. To better understand the evolution of ICMEs in interplanetary propagation, we identified 14 multipoint observed ICME events via various lists of ICMEs, which confirmed the multipoint associations previously made by other researchers for these events. We use the in situ measurements as well as model results of these 14 ICMEs to obtain the evolution of the ICMEs in interplanetary space. We found that the dependence of the average total magnetic field strength on the radial distance is &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;B&lt;/mi&gt;\u0000 &lt;mi&gt;t&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;∝&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1.68&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.17&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${B}_{t}propto {D}^{-1.68pm 0.17}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The radial dependence of the axial magnetic field strength is &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;B&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;∝&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1.54&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.15&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${B}_{0}propto {D}^{-1.54pm 0.15}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. These dependencies indicate that the decay rates of the magnetic field are slightly slower than expected from self-similar expansion. The relationship between radius of the flux rope and radial distance is &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mo&gt;∝&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;D&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;0.84&lt;/mn&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;0.22&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $Rpropto {D}^{0.84pm 0.22}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, which is closed to the expectation of self-similar expansion but still slightly lower. However, for each group of ICME, their radial dependence varies significantly. Only 36% of events are basically self-similar expansions. This may be due to the effect of the magnetic pressure difference and velocity difference between an ICME and the background solar wind on the ICME exp","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563436","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":"Solar Wind Discontinuities in the Outer Heliosphere: Spatial Distribution Between 1 and 5 AU","authors":"Zijin Zhang,&nbsp;Anton V. Artemyev,&nbsp;Vassilis Angelopoulos,&nbsp;Ivan Vasko","doi":"10.1029/2025JA034039","DOIUrl":"https://doi.org/10.1029/2025JA034039","url":null,"abstract":"<p>Solar wind discontinuities (SWDs) are kinetic plasma structures that significantly contribute to the spectrum of magnetic field fluctuations and solar wind heating. Using Juno spacecraft data from 1 AU to 5 AU, combined with measurements from Wind, ARTEMIS, and STEREO at 1 AU, we disentangle spatial (radial) and temporal (solar activity) variations of SWD properties. We find that (a) the occurrence rate of SWDs decreases with radial distance from the Sun, following a <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <mo>/</mo>\u0000 <mi>r</mi>\u0000 </mrow>\u0000 <annotation> $1/r$</annotation>\u0000 </semantics></math> relationship; (b) the SWD thickness increases with radial distance, but when normalized to the ion inertial length, the thickness remains almost unchanged within [1, 5]AU; (c) the SWD current density decreases with radial distance, but when normalized to the Alfvén current (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>J</mi>\u0000 <mi>A</mi>\u0000 </msub>\u0000 <mo>=</mo>\u0000 <mi>e</mi>\u0000 <mi>N</mi>\u0000 <msub>\u0000 <mi>V</mi>\u0000 <mi>A</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${J}_{A}=eN{V}_{A}$</annotation>\u0000 </semantics></math>, where symbols have their usual definitions), the current density remains almost unchanged within [1, 5]AU; (d) the probability distributions of SWD normalized thickness and current density remain constant over time (in the 5 year period of Juno cruise phase) at 1 AU. We discuss these results in the context of theories of the origin and dynamics of SWDs.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563438","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":"Investigating Magnetic Field Fluctuations in Jovian Auroral Electron Beams","authors":"A. Salveter,&nbsp;J. Saur,&nbsp;G. Clark,&nbsp;A. Sulaiman,&nbsp;B. H. Mauk,&nbsp;J. E. P. Connerney,&nbsp;B. Bonfond","doi":"10.1029/2025JA033816","DOIUrl":"https://doi.org/10.1029/2025JA033816","url":null,"abstract":"<p>The Juno spacecraft provides a unique opportunity to explore the mechanisms generating Jupiter's aurorae. Past analyses of Juno data immensely advanced our understanding of its auroral acceleration processes, however, few studies utilized multiple instruments on Juno in a joint systematic analysis. This study uses measurements from the Juno Ultraviolet Spectrograph (UVS), the Jupiter Energetic particle Detector Instrument (JEDI), and the Juno Magnetometer (MAG) from the first 20 perijoves. On magnetic field lines associated with the diffuse aurora, we consistently find small-scale magnetic field fluctuations with amplitudes of up to 100 nT on time scales of seconds to 1 min. On magnetic field lines directly linked to the main emission, the electron distribution is field-aligned, mostly broad-band in energy, and accompanied by large-scale magnetic field perturbations of several 100 nT on time scales of tens of min (except one case). These large-scale perturbations are generally associated with quasistatic field-aligned electric currents. Small-scale magnetic fields are not resolved over the main emission zone when the spacecraft is within four Jovian radii radial distance closer than radial distances four Jovian radii due to the digitization limit of the magnetometer. However, in all cases where Juno crosses the main auroral field lines beyond 4 R_J, the digitization limit is significantly reduced and we detect small-scale magnetic field fluctuations of 2–10 nT consistent with a turbulent spectrum. Associated energy fluxes projected to Jupiter can exceed 1,000 mW/m2. The general broad-band nature of the electron distributions and the consistent presence of small-scale magnetic field fluctuations over the main emission support that wave-particle interaction can dominantly contribute to power Jupiter's auroral processes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033816","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563077","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":"Impact of Solar Activity on Short Period Ionospheric Oscillations","authors":"Panagiotis Vergados,&nbsp;Anthony Mannucci,&nbsp;Guiping Liu","doi":"10.1029/2024JA033518","DOIUrl":"https://doi.org/10.1029/2024JA033518","url":null,"abstract":"<p>We study the characteristics of the Earth's ionosphere short period oscillations over multiple years spanning two solar maxima. We analyze the ground-based Global Navigation Satellite System vertical total electron content (TEC) at locations close to the magnetic equator in South America and India, as well as in North America, from January 2000 through December 2017. We use Morlet wavelets to spectrally analyze the ionospheric TEC variability over solar cycles 23 and 24 and find that the ionosphere exhibits dominant modes of oscillation at the same periods (5–6 days) as planetary waves. Interestingly, these oscillations manifest as 2–3 TECU fluctuations, are enhanced during spring, and show strong covariations with the 10.7 cm solar flux. We hypothesize that, once these short-period oscillations are formed, the solar activity drives their strength with distinct enhancements during solar maxima and pronounced suppressions at the transition from the solar cycle 23 to 24.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563437","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":"Exploring the Magnetotail From Low Altitudes: Evolution of Energetic Electron Flux During the Substorm Growth Phase","authors":"Weiqin Sun,&nbsp;Xiao-Jia Zhang,&nbsp;Anton V. Artemyev,&nbsp;Rumi Nakamura,&nbsp;Vassilis Angelopoulos","doi":"10.1029/2025JA033882","DOIUrl":"https://doi.org/10.1029/2025JA033882","url":null,"abstract":"<p>The magnetospheric substorm, which plays a crucial role in flux and energy transport across Earth's magnetosphere, features the formation of a thin, elongated current sheet in the magnetotail during its growth phase. This phase is characterized by a decrease in the equatorial magnetic field <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mi>z</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${B}_{z}$</annotation>\u0000 </semantics></math> and the stretching of magnetic field lines. Observing these large-scale magnetic field reconfigurations is challenging with single-point satellite measurements, which provide only spatially localized snapshots of system dynamics. Conversely, low-altitude spacecraft measurements of energetic electron fluxes, such as those from Electron Losses and Fields Investigation (ELFIN), offer a unique opportunity to remotely sense the equatorial magnetic field in the magnetotail during substorms by measuring the latitudinal variations of energetic electron isotropic fluxes. Because of strong scattering caused by the curvature of magnetic field lines, energetic electrons in the magnetotail are mostly isotropic. Consequently, variations in their fluxes at low altitudes are expected to reflect the reconfiguration of the magnetotail magnetic field. To better understand the connection between electron flux variation at low altitudes and magnetic field reconfiguration during substorms, we compared low-altitude ELFIN observations with simulations from the Rice Convection Model (RCM). The RCM, which assumes fully isotropic electron distributions, provides a robust framework for describing energetic electron dynamics in the plasma sheet and determining the self-consistent magnetic field configuration during substorms. The comparison of ELFIN observations and RCM simulations confirms our interpretation of electron flux dynamics at low altitudes during the substorm growth phase and validates the use of such observations to infer magnetotail dynamics during substorms.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536852","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}