Journal of Geophysical Research: Space Physics最新文献

{"title":"Electron Phase Space Densities in Geostationary Orbits as Measured With GK2A, GOES-16, and GOES-17 Satellites","authors":"C. H. Lee,&nbsp;J. Seon,&nbsp;W. H. Seol,&nbsp;K. H. Kim,&nbsp;D. E. Larson,&nbsp;G. K. Parks,&nbsp;H. U. Auster,&nbsp;W. Magnes,&nbsp;S. Kraft,&nbsp;D. Y. Lee,&nbsp;A. Boudouridis,&nbsp;P. T. M. Loto'aniu,&nbsp;J. V. Rodriguez","doi":"10.1029/2024JA033161","DOIUrl":"https://doi.org/10.1029/2024JA033161","url":null,"abstract":"<p>This study investigated electron phase space densities (PSDs) in geostationary orbits using data from Korea's geostationary satellite, GK2A, as well as GOES-16 and GOES-17 satellites. The PSDs were computed from electron fluxes measured by each satellite during a geomagnetically quiet period as defined by stringent conditions on geomagnetic activity. The conjunction of the satellites over invariant coordinates enabled electron PSDs from pairs of satellites to be compared to assess the extent of deviation of the PSD ratios from the expected ratio of one, as inferred from the Liouville theorem. The results show that PSDs from the satellites are sufficiently consistent to allow the estimation of the radial gradient of the PSDs. Comparisons of radial gradients estimated in this manner show that positive radial gradients prevail during geomagnetically quiet periods, whereas both positive and negative gradients may occur at similar frequencies during active periods. This study provides statistical insights into the physical mechanisms responsible for the observed radial gradient profiles based on findings from a wide range of local times during both geomagnetically quiet and active periods.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033161","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784295","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 Jupiter's Dawnside Magnetodisc: Using Juno Observations to Constrain a Radial Force-Balance Model","authors":"G. Provan,&nbsp;J. D. Nichols,&nbsp;S. W. H. Cowley,&nbsp;F. Bagenal,&nbsp;R. J. Wilson","doi":"10.1029/2024JA033658","DOIUrl":"https://doi.org/10.1029/2024JA033658","url":null,"abstract":"<p>This study investigates Jupiter's dawnside magnetodisc, using plasma and magnetic field measurements from Juno orbits 5 to 12 to refine a radial force-balance magnetodisc model. This iterative vector potential model examines variations in the azimuthal magnetodisc current, coupled with a magnetosphere-ionosphere coupling model from which the radial current is simultaneously obtained. Three key force-balance parameters are used: the hot plasma parameter (<i>pV</i>, Pa m T⁻¹), the mass outflow rate of cold iogenic plasma, and the height-integrated ionospheric Pedersen conductivity. Axisymmetric equilibrium outputs are compared to Juno's residual magnetic field and heavy ion density data between 15 and 60 R_J. Optimal parameter values for each orbit and overall current distributions are determined. Averaged modeled values are (1.63 ± 0.17) × 10⁷ Pa m T⁻¹ for the hot plasma parameter, 1,340 ± 350 kg s⁻¹ for the mass outflow rate, and 0.26 ± 0.08 mho for the Pedersen conductivity. The overall modeled magnetodisc azimuthal current to 60 R_J is 266 ± 23 MA, varying similarly to the currents determined by Connerney et al. (2020, https://doi.org/10.1029/2020JA028138) but typically ∼50 MA larger. Of this total, the hot plasma current 158 ± 13 MA is larger than the cold plasma current 109 ± 23 MA, and dominates in the inner region. The cold plasma current typically becomes the larger component beyond ∼35 R_J and exhibits greater orbit-to-orbit variability. The mass outflow rate from Io is the primary driver of magnetodisc current variability. The north-south summed radial magnetosphere-ionosphere coupling current 104 ± 31 MA is typically ∼40% of the total azimuthal current, with variations that are only weakly correlated.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033658","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784296","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":"Cluster Observations of Plasma in the High Latitude Magnetotail Associated With Cusp-Aligned Arcs","authors":"M. K. Mooney,&nbsp;S. E. Milan,&nbsp;M. Lester,&nbsp;I. Dandouras,&nbsp;C. Carr,&nbsp;A. N. Fazakerley","doi":"10.1029/2024JA033252","DOIUrl":"https://doi.org/10.1029/2024JA033252","url":null,"abstract":"&lt;p&gt;During periods of northward interplanetary magnetic field (IMF), the magnetospheric structure and dynamics are dramatically different compared to the southward IMF case. Previous studies using both observations and simulations have shown that under northward IMF the magnetotail becomes dominated by closed magnetic flux and associated trapped particle populations. In this study, we analyze three intervals of plasma observed in the high latitude magnetotail during a period of prolonged northward IMF, coinciding with observations of cusp-aligned arcs in the polar region. We observe that the plasma is typically observed by all 4 Cluster spacecraft near simultaneously and has some substructure observed on length scales of 0.5–1.5 &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;R&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{R}}_{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The plasma characteristics in each of the three intervals studied are similar. The ion and electron densities are on the order of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${10}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;–&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${10}^{0}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;cm&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{cm}}^{-3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The electron energies typically vary between &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${10}^{2}$&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;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${10}^{3}$&lt;/anno","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033252","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769972","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":"Properties of Lower Hybrid Drift Waves and Energy Transfer Near and Inside the Magnetic Reconnection Electron Diffusion Regions","authors":"Narges Ahmadi,&nbsp;Hantao Ji,&nbsp;Jongsoo Yoo,&nbsp;Robert Ergun,&nbsp;Izzy Thomas,&nbsp;Rahul Banka,&nbsp;Emma Schultz-Stachnik,&nbsp;Alma Alex","doi":"10.1029/2024JA033238","DOIUrl":"https://doi.org/10.1029/2024JA033238","url":null,"abstract":"<p>We investigate properties of lower hybrid drift waves (LHDWs) near and inside the electron diffusion regions in 17 magnetopause and 9 magnetotail reconnection events using Magnetospheric MultiScale (MMS) mission observations. Our analysis show that LHDW type depend on the electron beta, as electron beta increases LHDWs become more electromagnetic in nature. The energy transfer from electromagnetic fields to particles is higher in electrostatic LHDWs and it is largely in parallel direction with respect to the local magnetic field. Linear dispersion analysis shows that electrostatic LHDWs are perpendicular propagating while electromagnetic waves propagate in oblique directions and the normalized wavenumber of all LHDW types falls within 0.5–0.8 range. A simple estimate on the LHDW nonlinear saturation suggests a possibly important roles played by these waves in supporting the reconnection electric field.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770491","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 Latitudinal Dependency of the Solar Eclipse-Induced Ionosphere Response on 14 October 2023","authors":"Jianhui He,&nbsp;Xinan Yue,&nbsp;Huijun Le,&nbsp;Ruoxi Li,&nbsp;Xing Li,&nbsp;Yiqun Yu,&nbsp;Wenlong Liu,&nbsp;Jinbin Cao","doi":"10.1029/2025JA033765","DOIUrl":"https://doi.org/10.1029/2025JA033765","url":null,"abstract":"<p>We analyzed the three-dimensional (3-D) ionosphere response to the 14 October 2023 solar eclipse via assimilating multisource total electron content (TEC), including dense global navigation satellite system and the Constellation Observing System for Meteorology, Ionosphere, and Climate. The assimilations reveal a latitudinal dependency of the eclipse-induced TEC depletion, with larger reductions occurring at middle latitudes. In contrast to the electron density depletion throughout all ionosphere heights at middle latitudes, the equatorial ionization anomaly (EIA) region exhibits an altitudinal variation and an asymmetry pattern in density response. The implemented National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model simulations align well with the 3-D electron density assimilations. Diagnostic analysis indicates that the photo-chemical process plays a primary role in the larger depletion at middle latitudes, and the neutral wind transport provides a minor secondary contribution. In contrast, wind transport emerges as a dominant factor near the EIA region. The transequatorial plasma transport associated with northward neutral wind, driven by eclipse-induced local cooling, combined with partly enhanced upward ExB drift, mitigates the total TEC depletion near the EIA region. This study highlights the importance of the dynamic coupling for a self-consistent I-T system between the neutral atmosphere and the ionosphere during eclipses.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770489","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 Impact of 11 May 2024 Great Geomagnetic Storm on the Plasma Distribution Over the Indian Equatorial/Low Latitude Ionospheric Region","authors":"K. M. Ambili,&nbsp;R. K. Choudhary,&nbsp;Arya Ashok,&nbsp;Ajay Potdar,&nbsp;C. Vineeth,&nbsp;T. K. Pant","doi":"10.1029/2024JA033368","DOIUrl":"https://doi.org/10.1029/2024JA033368","url":null,"abstract":"<p>This study investigates the effects of the great geomagnetic storm of May 10–11, 2024, on the plasma density distribution in the ionosphere over the Indian equatorial and low-latitude regions. We utilized Vertical Total Electron Content (VTEC) as a proxy to understand the plasma density distribution. In conjunction with the equatorward neutral wind from the auroral region, the strom generated strong convective electric fields, penetrating down to the dip-equator, played a cruicial role in causing VTEC reduction at night (main phase) and enhancement during the day (recovery phase) on 11 May. Simultaneously, a decrease in VTEC of over 60% was observed in Bhopal, an equatorial ionization anomaly crest region. Undulations in the VTEC at the dip-equator correlated well with interplanetary electric field (IEFy) and magnetic field (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 </mrow>\u0000 <annotation> ${Delta }$</annotation>\u0000 </semantics></math>H) fluctuations. Analysis of the AE index suggests a strong equatorward wind surge due to intense auroral heating during the storm. Since the great storm occurred at night over India, meridional wind circulation played a prominent role. This study highlights the need for a more detailed analysis using multiple instruments and models to understand the response of the Indian equatorial and low-latitude regions during geomagnetic storms.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770490","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":"Different Faces of the Martian Magnetosphere","authors":"E. Dubinin,&nbsp;M. Fraenz,&nbsp;R. Modolo,&nbsp;M. Pätzold,&nbsp;S. Tellmann,&nbsp;G. DiBraccio","doi":"10.1029/2025JA033717","DOIUrl":"https://doi.org/10.1029/2025JA033717","url":null,"abstract":"<p>The Martian magnetosphere contains components of the induced and intrinsic magnetospheres. Since we can not get a global snapshot of the magnetosphere we use a statistical picture based on a large number of measurements. Depending on the choice of coordinate system and the data selection we can observe different faces of the Martian magnetosphere. If we map data in the Martian Solar Electric coordinate system, then we can separate the induced features of the magnetosphere which appears similar to the magnetosphere of Venus. If we use the Martian Solar Orbital coordinate system and select together the orbits with positive and negative <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mi>y</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${B}_{y}$</annotation>\u0000 </semantics></math>-component of the IMF, then the effects related to draped magnetic field and the high order harmonics of the crustal magnetic field are significantly weakened because of averaging over many orbits and a dipole-like magnetosphere of Mars becomes visible. If we select separately the orbits with positive and negative <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mi>y</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${B}_{y}$</annotation>\u0000 </semantics></math>-component we observe a twist of the magnetotail in the direction determined by the sign of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mi>y</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${B}_{y}$</annotation>\u0000 </semantics></math> that is typical for a hybrid magnetosphere with the induced and intrinsic components. The intrinsic and induced components are also well separated when we select the orbits with northward IMF. Then we observe the features that are somewhat similar to those at the Earth magnetosphere. When we use the MSO coordinates and separate by the phase of Mars rotation, the tail topology occurs more complex. This indicates that the effects of the local crustal magnetic field turn out as being also important.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033717","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770492","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 Ionospheric Response During the Super Geomagnetic Storm on May 10–11, 2024","authors":"Qingtao Wan,&nbsp;Guanyi Ma,&nbsp;Guiping Zhou,&nbsp;Jinghua Li,&nbsp;Jiangtao Fan","doi":"10.1029/2024JA033627","DOIUrl":"https://doi.org/10.1029/2024JA033627","url":null,"abstract":"&lt;p&gt;The ionospheric response in the Americas and Asia region was studied during the super geomagnetic storm on 10–11 May, 2024, characterized by a minimum Dst of −412 nT. Global Navigation Satellite System receivers at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;100&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;W&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $100{}^{circ}mathrm{W}$&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;100&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $100{}^{circ}mathrm{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; were utilized to study total electron content. Additionally, electron density profiles from Constellation Observing System for Meteorology Ionosphere and Climate occultation, foF2 from ionosondes, vertical ion drift from JULIA Medium Power radar, latitudinal distribution of electron density from Swarm B, and the [O/N2] ratios from TIMED/GUVI were also analyzed. The ionosphere in the Americas exhibited a positive storm, while Asia showed a negative storm. The presence of prompt penetration electric field and the equatorward wind surge were indicated by the increased upward ion drift and the enhancement of equatorial ionospheric anomalies (EIA). The observations of [O/N2] confirm the existence of equatorward expansion of neutral atmosphere, and the time delay of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${Delta }TEC$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; peak at mid-latitudes was related to the equatorward wind surge. For the first time, we investigated the dominant physical mechanism of ionospheric disturbance at different latitudes by analyzing the variation of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mi&gt;T&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${Delta }TEC$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; peak time with latitude. The estimated speed of disturbance winds was approximately 660 m/s at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;50&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $50{}^{circ}mathrm{N}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and 150 m/s at &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;37&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $37{}^{circ}mathrm{N}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. The","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749396","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":"Whistler Wave Propagation in a Dipole Magnetic Field: Two-Dimensional gcPIC Simulations","authors":"Yangguang Ke,&nbsp;Quanming Lu,&nbsp;Xinliang Gao,&nbsp;Jiuqi Ma,&nbsp;Junyi Ren,&nbsp;Xuan Zhou","doi":"10.1029/2025JA033759","DOIUrl":"https://doi.org/10.1029/2025JA033759","url":null,"abstract":"<p>Magnetospheric whistler waves are of fundamental importance in the formation of radiation belts and the generation of diffuse aurorae. Their propagation has been widely studied using satellite observations and numerical simulations because of their direct impact on the interactions with electrons. Although ray-tracing models have elucidated the propagation paths, wave normal angles (WNAs), and linear growth/damping of whistler waves, their nonlinear evolution, requiring kinetic simulation models, still remains unclear. In this study, we utilize gcPIC simulations to study whistler wave propagation in a dipole magnetic field, and compare the results with ray-tracing simulations. Ray-tracing simulations show that a parallel whistler wave gradually becomes oblique and experiences increasing linear damping during its propagation from the magnetic equator to high latitudes. Particle-in-cell simulations display nearly identical propagation paths and WNAs, but the amplitude evolution shows substantial differences. At lower latitudes, whistler waves will experience extra substantial damping compared with ray-tracing results, which is due to nonlinear Landau and cyclotron resonances. This difference becomes more pronounced when the wave amplitude is larger. Surprisingly, at higher latitudes, whistler waves will experience less damping, attributable to the electron plateau/beam distributions resulting from Landau trapping. Our study demonstrates the crucial role of nonlinear resonances and reshaped electron distributions in modeling the evolution of whistler waves in the Earth's magnetosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749395","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":"Dynamical Response of the Middle and Upper Atmosphere to the February 2018 Sudden Stratospheric Warming Revealed by MERRA-2 and SABER","authors":"Guiping Liu,&nbsp;Fabrizio Sassi,&nbsp;Ruth S. Lieberman,&nbsp;Lawrence Coy,&nbsp;Steven Pawson","doi":"10.1029/2024JA033528","DOIUrl":"https://doi.org/10.1029/2024JA033528","url":null,"abstract":"<p>The middle and upper atmosphere plays a critical role in linking the lower atmosphere forcing with ionospheric variability, especially during strong atmospheric activities. This study examines the dynamical response in the altitude range from ∼20 to 80 km to a major Sudden Stratospheric Warming (SSW) event peaking on 11 February 2018. We compare the reanalysis product of the Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) from the Goddard Earth Observing System (GEOS) to the satellite observations by Thermosphere Ionosphere and Mesosphere Electric Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) TIMED/SABER that are not assimilated in MERRA-2. Our study shows that the zonal mean wind and temperature and planetary wave 1 and 2 variations are generally consistent between the reanalysis and observations. We also identify a strong ∼6 day wave propagating both westward and eastward with zonal wavenumber-1 with the westward propagating component likely generated by baroclinic/barotropic instability. However, important disagreements arise specifically above ∼60 km, where the wind and temperature are not well represented in MERRA-2, causing differences in the day-to-day development of 6 day wave. This study highlights the need for additional assimilation of mesospheric data and development of high-altitude vertically extended GEOS model.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143741445","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}