Journal of Geophysical Research: Space Physics最新文献

{"title":"Modeling the Internal Redistribution of Earth's Proton Radiation Belt by Interplanetary Shocks","authors":"Alexander R. Lozinski,&nbsp;Adam C. Kellerman,&nbsp;Jacob Bortnik,&nbsp;Richard B. Horne,&nbsp;Ravindra T. Desai,&nbsp;Sarah A. Glauert","doi":"10.1029/2025JA033871","DOIUrl":"https://doi.org/10.1029/2025JA033871","url":null,"abstract":"<p>A large proton belt enhancement occurred on 24 March 1991 following an interplanetary shock that impacted the dayside magnetopause at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>03:40 UT. Its formation was measured by the proton telescope aboard CRRES and attributed to the injection and inward transport of solar energetic particles (SEPs) by an azimuthally propagating electric field pulse induced by the shock's compression of the magnetosphere. This led to an increase in the flux of high energy (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math>25 MeV) protons by several orders of magnitude at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 <mo>≈</mo>\u0000 <mn>2.5</mn>\u0000 </mrow>\u0000 <annotation> $Lapprox 2.5$</annotation>\u0000 </semantics></math> which has been well-studied. However, a flux enhancement by up to one order of magnitude was also seen in 1–20 MeV protons at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 <mo>≈</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $Lapprox 2$</annotation>\u0000 </semantics></math>. Protons in this energy range pose a hazard to orbiting spacecraft as a major contributor to solar cell nonionizing dose. The 1–20 MeV enhancement cannot be explained by the inward transport of a solar proton source, because a newly injected source population at the required energy would have a drift velocity too low to interact with the pulse. Instead, we hypothesize that the 1–20 MeV enhancement was caused by the redistribution of radiation belt protons to different drift shells by the pulse. To test this hypothesis, we apply a novel method to predict the change in phase space density during a shock event which utilizes reverse-time particle tracing simulations. Our results show that the 1–20 MeV enhancement can be accounted for by internal redistribution as hypothesized. We thus identify a new mechanism for proton belt enhancements that does not depend on a SEP source and present a way to model it.</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/10.1029/2025JA033871","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144323574","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":"On Detection of Super Equatorial Plasma Bubbles in the American Sector During the 10–11 October 2024 Geomagnetic Storm","authors":"Irina Zakharenkova,&nbsp;Iurii Cherniak,&nbsp;Andrzej Krankowski,&nbsp;Cesar E. Valladares,&nbsp;Cesar De la Jara Sanchez","doi":"10.1029/2025JA033709","DOIUrl":"https://doi.org/10.1029/2025JA033709","url":null,"abstract":"<p>Multi-instrument analysis of ground-based and satellite observations (GNSS, ionosondes, magnetometers, Swarm, GOLD) revealed the formation of giant equatorial plasma bubbles (super-EPBs) in the American sector during the 10–11 October 2024 geomagnetic storm. Development of spectacular depletions, stretching between 30°N and 50°S (∼40°MLAT) across American continents with estimated apex altitudes of ∼3,500–4,000 km, was linked to storm-induced prompt penetration electric fields. Sudden southward turning of interplanetary magnetic field Bz component occurred at ∼22:40 UT, 10 October 2024, when the dusk sector reached western South America. Following a strong uplift of the ionosphere over Jicamarca/Peru by more than 400 km, the super-EPBs developed in this region, rapidly reaching midlatitudes. In the equatorial region, super-EPBs were confined to 65°–75°W longitudes. This fortunate localization gives a rare chance to trace super-EPB evolution near-entirely, from equatorial to middle latitudes in both hemispheres, due to extensive ground-based GNSS coverage. This allows us to unveil the complexity of super-EPB evolution with storm's progress: (a) Initial formation of post-sunset super-EPBs as field-oriented, inverted C-shape structures near 65°–75°W, (b) westward drift of outmost parts of these structures across midlatitudes from their original location, (c) formation of fresh post-midnight EPBs over the same locations as post-sunset EPBs, persisting until early morning. Ionosondes in North America midlatitudes (∼42°MLAT) registered rare observations of Spread-F associated with storm-induced EPBs. Strong amplitude scintillations were observed from sunset to sunrise. Super-EPBs bringing ionospheric irregularities and scintillations to unexpectedly high latitudes represent a perplexing phenomenon connecting physical processes across equatorial, middle and high latitudes during geomagnetic disturbances.</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":"144315330","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 Numerical Investigation of Equatorial Ionospheric Radial Currents During the Total Solar Eclipse on 29 March 2006","authors":"Hao Xia,&nbsp;Hui Wang,&nbsp;Kedeng Zhang","doi":"10.1029/2025JA033775","DOIUrl":"https://doi.org/10.1029/2025JA033775","url":null,"abstract":"<p>The solar eclipse is a common phenomenon, which produces significant disturbances in the ionosphere. Based on the CHAllenging Minisatellite Payload (CHAMP) observations and the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations, this work first investigates the responses of the Ionospheric Radial Currents (IRC) to the total solar eclipse on 29 March 2006. During the solar eclipse, IRC significantly enhanced inward. The intensity increased from −0.55 nA/m² at pre-eclipse to −3.97 nA/m² at eclipse, and ultimately recovered to −0.96 nA/m², yielding a structure similar to letter “V.” The TIEGCM simulations show that the inward IRC disturbance (ΔIRC) was dominated by the dynamo current (ΔDyn). During the eclipse period, the neutral temperature in the eclipse path was significantly decreased by the sunlight shadow. Above the dip equator, a westward local wind was generated, driving the F-layer dynamo and enhancing the inward ΔDyn. The inward ΔDyn at F-layer could separate the charged particles and generate the outward polarization electric field (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>E</mi>\u0000 </mrow>\u0000 <mi>z</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${{Delta }E}_{z}$</annotation>\u0000 </semantics></math>). This outward <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>E</mi>\u0000 </mrow>\u0000 <mi>z</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${{Delta }E}_{z}$</annotation>\u0000 </semantics></math> fed back to drive an outward polarization current (ΔPoL), modulating the density of ΔIRC. In addition, the Pedersen conductivity was suppressed by the upward movement of plasma at the dip equator owing to the disturbed northward winds.</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":"144315066","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 Topside Ionospheric Responses to the November 2003 Superstorm Using CHAMP, GRACE, and SAC-C Satellite Observations","authors":"Hailun Ye,&nbsp;Wen Yi,&nbsp;Jianfei Wu,&nbsp;Bingkun Yu,&nbsp;Jiahao Zhong,&nbsp;Xianghui Xue,&nbsp;Penghao Tian,&nbsp;Chi Long,&nbsp;Jian Li,&nbsp;Maolin Lu,&nbsp;Chong Wang,&nbsp;Tingdi Chen,&nbsp;Xiankang Dou","doi":"10.1029/2024JA033478","DOIUrl":"https://doi.org/10.1029/2024JA033478","url":null,"abstract":"<p>In this work, topside Total Electron Content (TEC) obtained from CHAMP, GRACE, and SAC-C, along with in situ electron density (Ne) measurements from CHAMP and GRACE, were utilized to investigate the response of the topside ionosphere to the November 2003 superstorm, particularly during its recovery phase. Observations from multiple satellites revealed unexpected and persistent enhancements in the topside ionosphere during the late recovery phase (22–24 November 2003), which were more pronounced in the Eastern Pacific sector than in the Asian sector, indicating notable longitudinal differences. Intriguingly, the opposite inter-hemispheric asymmetries of the enhancement were observed near the peak height of F2 and the topside ionosphere on the dayside in the Eastern Pacific sector. During the late recovery phase, the storm-time enhancement in the eastward electric field and trans-equatorial wind likely contributed to the observed positive ionospheric storm effects and inter-hemispheric asymmetry, respectively. Additionally, this study confirmed substantial enhancements in the dayside topside ionosphere during the storm's main phase on 20 November 2003. These findings underscore the need for a global, multi-instrumental approach to fully understand the diverse responses of the topside ionosphere to geomagnetic storms.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315250","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":"Preconditioning of the Interplanetary Medium Due To Isolated ICMEs","authors":"Primož Kajdič,&nbsp;Manuela Temmer,&nbsp;Xochitl Blanco-Cano","doi":"10.1029/2025JA033887","DOIUrl":"https://doi.org/10.1029/2025JA033887","url":null,"abstract":"<p>We perform a systematic study of the preconditioning of the interplanetary (IP) medium due to isolated IP coronal mass ejections (ICMEs). Preconditioning is highly relevant when ICMEs, ejected in close succession and direction, modify the IP medium to allow subsequent ICMEs to propagate more freely, decelerate less, and retain higher kinetic energy at larger distances. We base our study on a sample of carefully selected events. The IP medium is analyzed during time intervals of 48 hr before and after the ICMEs in order to statistically quantify their impact on the properties of the solar wind (SW) and interplanetary magnetic field (IMF). We find that the SW behind ICMEs on average exhibits reduced density (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 </mrow>\u0000 <annotation> ${-}$</annotation>\u0000 </semantics></math>41%) and dynamic pressure (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 </mrow>\u0000 <annotation> ${-}$</annotation>\u0000 </semantics></math>29%), and increased total velocity (+15%), while the trailing IMF is more intense (+14%) and more radially aligned (13<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>). The results suggest that even relatively low speed ICMEs can significantly precondition the IP medium. The results are relevant for better understanding of CME propagation and SW interaction, and hold implications for heliospheric models and applied research of space weather.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315202","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":"The Variations of High-Frequency Ionospheric Absorption Discrepancy Between the Ordinary and Extraordinary Wave During Daytime in China Region","authors":"Xiaoli Jiang,&nbsp;Huimin Li,&nbsp;Lixin Guo,&nbsp;Dalin Ye,&nbsp;Xiao Meng","doi":"10.1029/2024JA033316","DOIUrl":"https://doi.org/10.1029/2024JA033316","url":null,"abstract":"<p>By utilizing an ionospheric absorption model, the variations of high-frequency ionospheric absorption discrepancy between the X-mode and O-mode wave, at two different propagation direction links (north-south path and east-west path) in China region during the daytime, are explored. In this paper, the two main factors, namely frequency and propagation of direction, affecting on the trend of absorption difference between the X-mode and O-mode wave, are investigated. It is found that the absorption discrepancy between the X-mode and O-mode wave decreases with the increase in frequency, with the exception of two certain inflexion points under various elevation angle conditions. The entire decrease trend is attributed to the absorption coefficient, which is dominated by the parallel component of the magneto-ionic parameter. The occurrence of the two certain inflexion points (the first inflexion one is negative, the other is positive) on the absorption difference-frequency curves, resulting from the successive appearance of the Pedersen ray for the O-mode and X-mode, respectively. In addition, it is interesting that the absorption discrepancy in the north-south propagation link is always greater than that in the east-west propagation link at any frequency under various elevation angle conditions. It is mainly determined by the trend of the difference in the parallel component of the magneto-ionic parameter.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315123","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":"Multi-Spacecraft Analysis of Dipolarization Events With Inductive, Radial Electric Fields in the Inner Magnetosphere","authors":"H. Matsui,&nbsp;R. B. Torbert,&nbsp;C. J. Farrugia,&nbsp;T. J. Metivier,&nbsp;I. J. Cohen,&nbsp;R. E. Ergun,&nbsp;J. F. Fennell,&nbsp;Yu. V. Khotyaintsev,&nbsp;P.-A. Lindqvist,&nbsp;C. T. Russell,&nbsp;R. J. Strangeway,&nbsp;D. L. Turner","doi":"10.1029/2025JA033807","DOIUrl":"https://doi.org/10.1029/2025JA033807","url":null,"abstract":"<p>Dipolarization events with inductive, radial electric fields are investigated with multi-spacecraft analysis techniques. Observations by Magnetospheric Multiscale with separations around ion scales are used to study spatial and temporal variations of these events in the inner magnetosphere. <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>J</mi>\u0000 <mo>×</mo>\u0000 <mi>B</mi>\u0000 </mrow>\u0000 <annotation> $Jtimes B$</annotation>\u0000 </semantics></math> force, magnetic pressure force, and tension force are compared based on the Taylor expansion method, which includes the curlometer technique. The magnetic pressure force, possibly related to energetic particles and magnetic flux transported from the magnetotail, tends to contribute to the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>J</mi>\u0000 <mo>×</mo>\u0000 <mi>B</mi>\u0000 </mrow>\u0000 <annotation> $Jtimes B$</annotation>\u0000 </semantics></math> force for the background components near the equator, while the tension force, related to Alfvén waves, contributes to the fluctuating components or outside the equator. The scale length is thousands of km for the background components, probably related to meso-scale structures, while that length is tens to a thousand km for fluctuating components. The small-scale fluctuations would be related to particle acceleration. The fluctuations are inferred to be Alfvén waves with quasi-perpendicular propagation directions and with finite temperature or kinetic effects. These fluctuations could be intermittent and not self-similar between different inter-spacecraft distances. Some energy transfer from fluctuations to particles would occur.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315249","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":"Ionospheric Responses to Two Consecutive Geomagnetic Storms of the Ascending Phase of the Solar Cycle 25 Over the Indian Sector","authors":"S. N. Remya,&nbsp;K. Unnikrishnan,&nbsp;Smitha V. Thampi,&nbsp;H. Sreekumar","doi":"10.1029/2024JA033159","DOIUrl":"https://doi.org/10.1029/2024JA033159","url":null,"abstract":"<p>This study explores how consecutive minor geomagnetic storms impacted ionospheric conditions across the Indian sector. Utilizing in situ Total Electron Content (TEC) data from SWARM(A) and ground-based Global Navigation Satellite System (GNSS) TEC, the analysis spans the Indian longitude sector during two consecutive minor storms occurring on 3–4 November 2022 and 7–8 November 2022. On 7th November 2022, a significant M5-class solar flare from Sunspot AR3141 contributed to elevated geomagnetic activity in the Indian sector. The first storm was marked by a modest daytime TEC enhancement paired with nighttime suppression, whereas the second storm elicited a consistently positive ionospheric response throughout both day and night, indicating a sustained TEC increase over the region. Observations from TIMED/GUVI confirm compositional changes during the storms, while temporal variations in the real-time model of Equatorial Electric Field (EEF) are analyzed to understand the equatorial eastward electric field dynamics over the Indian sector. GNSS-based TEC data from Changanacherry (9.45°N, 76.54°E) reveal westward Prompt Penetration Electric Fields (PPEFs) as drivers of fluctuations during the second storm. The analysis of consecutive minor storms, focusing on local time variations, offers deeper insights into their dynamics and impact while highlighting the complex interplay between solar activity, storm-time electric fields, and ionospheric responses.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315124","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":"First Simultaneous Multi-Point Observation of the Local-Time Asymmetry of keV Ions in the Dayside Magnetosphere During the Main Phase of the Geomagnetic Storm","authors":"Megha Pandya,&nbsp;Yusuke Ebihara,&nbsp;Denny M. Oliveira,&nbsp;Marilia Samara,&nbsp;Mei-Ching Fok,&nbsp;Ankush Bhaskar,&nbsp;Cristian P. Ferradas,&nbsp;Takashi Tanaka,&nbsp;Robert Michell,&nbsp;Geoffrey Reeves,&nbsp;Jerry W. Manweiler","doi":"10.1029/2025JA033793","DOIUrl":"https://doi.org/10.1029/2025JA033793","url":null,"abstract":"<p>Our study presents the first simultaneous multi-point observation of the local-time asymmetry of 10's–100's of keV energy ion fluxes during the main phase of the geomagnetic storm that occurred on 7 September 2017. During this event, Van Allen Probe-A and Van Allen Probe-B observed two different tendencies. The ion fluxes increased by an order of magnitude in the noon-dusk sector, while decreasing by one order or more in the dawn-noon sector, offering a unique opportunity to investigate this asymmetry. Numerical simulations employing the Comprehensive Inner Magnetosphere-Ionosphere model with time-dependent electric fields from Global Magnetohydrodynamic (MHD) simulations revealed that the local time asymmetry in ion fluxes is associated with a sharp southward turning of the interplanetary magnetic field (IMF) and long-duration persistent westward electric field. These factors cause ions to drift toward the dusk sector, while preexisting ions on the dayside drift sunward and escape the inner magnetosphere. Our findings provide the first direct observational evidence of ring current asymmetry, complementing and supporting prior statistical studies and simulation results.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144300469","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":"About Forward-Facing Slow Mode Waves at the Magnetopause","authors":"Bengt U. Ö. Sonnerup,&nbsp;Richard E. Denton","doi":"10.1029/2025JA034031","DOIUrl":"https://doi.org/10.1029/2025JA034031","url":null,"abstract":"<p>We review a theoretically predicted, hyperbolic MHD feature, exhibited in the field and plasma flow at the magnetopause, namely that of upstream-traveling, slow-mode waves, first predicted in the 1950s, but, so far, not identified in spacecraft data. Today's high-quality observations at Earth's magnetopause now invites a serious attempt to check the prediction. The required theoretical background and analysis methodology is summarized and further developed. The study is limited to elongated disturbance structures, such as bulges, on the magnetopause that are approximately two-dimensional and, in their proper frame, time independent. Most of the analysis tools are applicable to data from a single spacecraft. Subsequent papers could employ data from multi-spacecraft missions, such as the four-spacecraft Magnetospheric Multi-Scale mission. Such data will permit the study of many additional details. Because they are mathematically intertwined, both elliptic and hyperbolic signatures will be examined. The three key points illustrate the important role played by magnetic-variance analysis in the study of field perturbations in the vicinity of the magnetopause. Its most common use to date has been for the analysis of the magnetic fields from spacecraft crossings of the magnetopause, where the minimum variance direction can provide an estimate, not always of high quality, of the direction normal to the magnetopause layer. In the present paper, magnetopause traversals play only a secondary role; our primary objective is to analyze field perturbations near the magnetopause, for which we show that the ideal minimum-variance direction is tangential, rather than normal, to the unperturbed magnetopause surface.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 6","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144300468","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}