Journal of Geophysical Research: Space Physics最新文献

{"title":"Atmospheric Semidiurnal Solar Tide Response to Sudden Stratospheric Warmings in the JAGUAR-DAS Whole Neutral Atmosphere Reanalysis (JAWARA) During 2004–2023","authors":"Y. Yamazaki,&nbsp;K. Sato,&nbsp;D. Koshin,&nbsp;R. Yasui","doi":"10.1029/2024JA033688","DOIUrl":"https://doi.org/10.1029/2024JA033688","url":null,"abstract":"<p>The migrating semidiurnal solar tide (SW2) originating from the troposphere and stratosphere is a known source of variability in the thermosphere-ionosphere system, and thus is important for accurate space weather prediction. Previous studies have established that the upward-propagation of SW2 into the lower thermosphere can be influenced by Arctic sudden stratospheric warmings (SSWs). In particular, the recent study by Yamazaki and Siddiqui (2024, https://doi.org/10.1029/2023jd040222) showed that the component of SW2 that is antisymmetric about the equator is enhanced. However, their study had a limitation in time resolution, as the satellite data they used required a 60-day integration for determining tides. The present study resolves this issue by using hourly temperature data from the JAGUAR-DAS Whole neutral Atmosphere Reanalysis (JAWARA). SW2 variability in the lower thermosphere is examined for all the boreal winters (December–February) from 2004/2005 to 2022/2023. We show that following the major SSWs in the boreal winters 2005/2006, 2008/2009, 2012/2013, and 2018/2019, the amplitude of SW2 increased and the phase of SW2 became more antisymmetric about the equator. SW2 remained altered during elevated stratopause events. Similar changes occurred during the minor SSW in the boreal winter 2011/2012, which was accompanied by an elevated stratopause event. The changes in SW2 can be well represented by the enhancement of the antisymmetric (2,3) Hough mode of classical tidal theory. The (2,3)-mode amplitude in the lower thermosphere is negatively correlated (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>R</mi>\u0000 </mrow>\u0000 <annotation> $R$</annotation>\u0000 </semantics></math> = <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 </mrow>\u0000 <annotation> ${-}$</annotation>\u0000 </semantics></math>0.72) with the zonal mean temperature at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>80</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $80{}^{circ}$</annotation>\u0000 </semantics></math>N at 50 km, which undergoes cooling during elevated stratopause events.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033688","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521944","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":"Pitch-Angle and Energy Electron Fluxes Distributions in the Discrete Aurora","authors":"George V. Khazanov,&nbsp;Emanuel N. Krivorutsky,&nbsp;Robert Sheldon,&nbsp;Alex Glocer","doi":"10.1029/2024JA033669","DOIUrl":"https://doi.org/10.1029/2024JA033669","url":null,"abstract":"<p>The energy and pitch-angle distribution of precipitating auroral electrons determine the efficiency of magnetosphere–ionosphere (MI) coupling. This makes the analysis of their formation important for all types of electron precipitation events, especially for the region of discrete aurora that is associated with the global upward ionospheric current system. We simulate the observed directional and differential energy fluxes in the region of discrete aurora. We found that the observed directional energy flux is more magnetically field-aligned for injected electrons with lower temperature and accelerated in the region located closer to the observer. We conclude that the data of the Science and Technology Satellite-I mission (Park et al., 2014, https://doi.org/10.1002/2013JA019497) with prevailing large pitch angles are dominated by events with high temperatures and/or large distances between the accelerating region and the observer. We also found the observed specific differential energy fluxes of the Fast Auroral Snapshots mission (Dombeck et al., 2018, https://doi.org/10.1029/2018ja025749) can be explained by assuming that every event is composed of particles accelerated by different potential drops. The electron distribution function is calculated from the observed downward and upward energy fluxes. It is constant in some energy range. We found that the plateau boundaries coincide with the region of the positive growth rate of Langmuir-beam waves. This is in agreement with the quasi-linear beam relaxation mechanism proposed to explain the formation of a plateau on the distribution function of precipitating auroral electrons.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521963","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":"Coincident/Simultaneous Observations of Stratospheric Concentric Gravity Waves and Concentric Traveling Ionospheric Disturbances Over the Continental U.S. in 2022","authors":"Masaru Kogure,&nbsp;Jia Yue,&nbsp;Min-Yang Chou,&nbsp;Huixin Liu,&nbsp;Yuichi Otsuka,&nbsp;Cora E. Randall,&nbsp;Lars Hoffmann,&nbsp;Yuta Hozumi","doi":"10.1029/2024JA033429","DOIUrl":"https://doi.org/10.1029/2024JA033429","url":null,"abstract":"<p>This study examines the seasonal distributions of simultaneous stratospheric concentric gravity waves (GWs) observed by the Atmospheric Infrared Sounders and concentric traveling ionospheric disturbances (TIDs) detected by the ground-based Global Navigation Satellite System Total Electron Content observations over the U.S. in 2022, to illustrate the mesoscale vertical coupling between the lower atmosphere and the ionosphere. We compared epicenters of GWs and TIDs in the stratosphere and ionosphere with tropospheric weather conditions and background winds in the thermosphere. Epicenters of concentric TIDs associated with stratospheric concentric GWs correspond to areas with high convective available potential energy over the central to eastern U.S. (∼60–110<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $mathit{{}^{circ}}$</annotation>\u0000 </semantics></math>W) in summer and over the southern U.S. (south of ∼40<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 <mi>N</mi>\u0000 </mrow>\u0000 <annotation> $mathit{{}^{circ}}mathrm{N}$</annotation>\u0000 </semantics></math>) in spring and fall. Conversely, in fall to spring, epicenters over the northern U.S. (north of ∼40<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 <mi>N</mi>\u0000 </mrow>\u0000 <annotation> $mathit{{}^{circ}}mathrm{N}$</annotation>\u0000 </semantics></math>) appeared south of regions with high extratropical cyclone activity. These findings suggest that convection was a primary source of concentric GWs driving TIDs over the continental U.S. during all four seasons, although the specific weather phenomena associated with the convection varied by season. Convection over the central to eastern U.S. in summer and the southern U.S. in spring could be linked to thunderstorms. In contrast, convection over the northern U.S. from fall through spring was likely linked to extratropical cyclones. We also found that concentric TIDs were linked to 66% of the stratospheric concentric GW events (195 events in total), underscoring the significant role of convection as a source of TIDs in the lower atmosphere and its contribution to the vertical coupling.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033429","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513844","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":"Superposed Epoch Analysis of Stream Interaction Regions at 1 au During Solar Minimum With Turbulence Geometry Decomposition: Implications for Galactic Cosmic Ray Transport","authors":"J. G. Alonso Guzmán,&nbsp;K. Ghanbari,&nbsp;V. A. Florinski,&nbsp;R. A. Leske,&nbsp;L.-L. Zhao,&nbsp;X. Zhu,&nbsp;A. Silwal,&nbsp;N. S. M. Subashchandar","doi":"10.1029/2024JA033567","DOIUrl":"https://doi.org/10.1029/2024JA033567","url":null,"abstract":"<p>In the inner heliosphere, stream interaction regions (SIR), where fast and slow solar wind streams meet, modulate the intensity of galactic cosmic rays (GCR) on the timescale of a few days. We perform a superposed epoch analysis (SEA) of solar wind, magnetic field, and high-energy particle count rate data from the Advanced Composition Explorer to calculate the average bulk and turbulent features of SIRs associated with strong GCR depressions, as well as a mean percentage change profile for the galactic proton flux during these events. In particular, we split the power of nearly incompressible magnetic turbulence throughout the SIR epoch into the common slab and 2D modes, since these contribute to energetic particle diffusion in different directions relative to the background, time-averaged field. We use the SEA results to compute parallel and perpendicular diffusion coefficients for GCRs during the passage of an average SIR and discuss our findings in the context of the particle observations and prior research. Our results suggest that GCR depletions through an SIR are primarily driven by a sharp decrease in the diffusion coefficients.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513488","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":"Magnetosheath Control of the Cross Polar Cap Potential: Correcting for Measurement Uncertainty in Space Weather","authors":"C. O’Brien,&nbsp;B. M. Walsh,&nbsp;E. G. Thomas","doi":"10.1029/2024JA033468","DOIUrl":"https://doi.org/10.1029/2024JA033468","url":null,"abstract":"&lt;p&gt;This study quantifies the variation and apparent saturation of the cross polar cap potential &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;ϕ&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({phi }_{PC}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; with respect to the motional electric field &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({E}_{M}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; in the solar wind and magnetosheath. The electric potential across the polar cap &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;ϕ&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({phi }_{PC}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is often observed to respond linearly to solar wind driving during weak driving and nonlinearly during strong driving, with &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;ϕ&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${phi }_{PC}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; eventually responding less and less to increased driving. This effect is called “polar cap potential saturation” and has been observed in many studies that correlate some measure of solar wind driving (typically the motional electric field &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;E&lt;/mi&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${E}_{M}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) with &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;ϕ&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mi&gt;C&lt;/m","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033468","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513842","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":"Ion Phase Space Density Profiles Within the Magnetosphere of Saturn: Investigating the Source of Suprathermal Ions","authors":"R. C. Allen,&nbsp;S. K. Vines,&nbsp;C. P. Paranicas,&nbsp;W. Mo,&nbsp;K. Dialynas","doi":"10.1029/2024JA033563","DOIUrl":"https://doi.org/10.1029/2024JA033563","url":null,"abstract":"<p>Phase space density (PSD) profiles at fixed values of the first two adiabatic invariants (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>μ</mi>\u0000 </mrow>\u0000 <annotation> ${upmu }$</annotation>\u0000 </semantics></math>; magnetic moment and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math>; longitudinal invariant) versus <i>L</i> shell provide a quantitative way to investigate the sources, losses, and radial transport of plasma and energetic charged particles within a planetary magnetosphere. PSD profiles have been obtained from the Magnetosphere Imaging Investigation/Charge-Energy-Mass Spectrometer (MIMI/CHEMS) for H⁺, W⁺, O⁺⁺, H₂⁺, He⁺, and He⁺⁺ for the period Cassini was in orbit around Saturn (July 2004 until September 2017). Beyond the expected variations for all species due to the suprathermal spectral slopes, the PSD profiles also show significantly more loss for lower <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math> (i.e., more equatorially mirroring or “trapped”) populations. This dependency of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>k</mi>\u0000 </mrow>\u0000 <annotation> $k$</annotation>\u0000 </semantics></math> for loss is consistent with higher loss rates of trapped populations in the inner magnetosphere (&lt;10 R_S) due to neutral densities being more equatorially confined. The PSD radial profiles of all species, regardless of solar wind-origin (e.g., H⁺, He⁺, He⁺⁺) or magnetospheric-origin (e.g., H⁺, W⁺, H₂⁺, and O⁺⁺), indicate that the outer magnetosphere is the predominant region of non-adiabatically accelerated lower energy plasma that may be a source of the suprathermal ions. Mission-averaged PSD profiles are also used along with the computed PSD profile near an interchange injection event to estimate the original <i>L</i> shell of injected H⁺ and W⁺ ions. For this injection event, the estimated source of both the H⁺ and W⁺ ions was between 1 and 2 Saturn radii (R_S) away, consistent with previous studies of interchange injection events at Saturn.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033563","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513843","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":"Low-Latitude Ionospheric Responses to the Severe Geomagnetic Storm During 23–25 April 2023 Over the American Sector","authors":"Pengfei Hu,&nbsp;Gang Chen,&nbsp;Shaodong Zhang,&nbsp;Wanlin Gong,&nbsp;Min Zhang","doi":"10.1029/2024JA033692","DOIUrl":"https://doi.org/10.1029/2024JA033692","url":null,"abstract":"<p>The impacts of the severe geomagnetic storm on 23–25 April 2023 on the low-latitude ionosphere over the American sector are investigated. Based on the ground-based and spaceborne instruments, a series of storm-associated ionospheric disturbances have been observed as follows: (a) The eastward Prompt Penetration Electric Fields intensified the equatorial upward <i>E</i> × <i>B</i> drift, and enhanced the Equatorial Ionization Anomaly (EIA) during the first main phase. (b) The EIA asymmetry in the region east of 70°W and one-sided F3 layer in the northern hemisphere are observed and are attributed to the strong southward transequatorial winds. (c) The disturbances of electric field and neutral winds raised the low-latitude and equatorial F-layer dramatically, and generated post-midnight Equatorial Plasma Bubbles. These bubbles rapidly extended to the magnetic latitude of 30°, corresponding to a rare Apex altitude of ∼2,600 km at magnetic equator. (d) On 24 April, the thermospheric composition disturbances with high ΣO/N₂ were concentrated in the southern hemisphere, and resulted in the positive storm over South America.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513487","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":"Asymmetry in the Ring Current During Geomagnetic Disturbances","authors":"G. E. Bower,&nbsp;S. E. Milan,&nbsp;S. Imber,&nbsp;A. Schillings,&nbsp;A. Fleetham,&nbsp;C. Beggan,&nbsp;J. W. Gjerloev","doi":"10.1029/2024JA033492","DOIUrl":"https://doi.org/10.1029/2024JA033492","url":null,"abstract":"<p>Geomagnetic disturbances (GMDs) are defined as rapid changes in the magnetic field of the Earth that can lead to geomagnetically induced currents (GICs). Recent studies have shown that there are two main populations of GMDs, one in the pre-midnight sector and one in the dawn sector. The pre-midnight GMDs have been related to the substorm current wedge. The dawn population of GMDs has previously been found to occur during multiple intensification events. We adapt the SOPHIE substorm list to identify more instances of multiple intensifications. Recent models suggest the formation of a “dawnside current wedge” (DCW) during the main phase of storms that could lead to dawn sector GMDs. We investigate GMDs at all latitudes using the SuperMAG local time indices (SMR-LT), where SMR-LT are local time measurements of the magnetic field at low latitudes. During multiple intensification events the dawn sector low latitude magnetic field between 3 and 9 MLT (SMR06) is typically higher than the dusk sector between 15 and 21 MLT (SMR18), which is indicative of a DCW. Statistical analysis of the local time ring current indices during the dawn and pre-midnight GMDs shows that the dawn GMDs occur when the difference between the dawn sector and dusk sector SMR values (SMR06-SMR18) is largest and thus when there is a DCW.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033492","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489838","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":"Identifying the Growth Phase of Magnetic Reconnection Using Pressure-Strain Interaction","authors":"M. Hasan Barbhuiya,&nbsp;Paul A. Cassak,&nbsp;Alex Chasapis,&nbsp;Michael A. Shay,&nbsp;Giulia Cozzani,&nbsp;Alessandro Retinò","doi":"10.1029/2024JA033446","DOIUrl":"https://doi.org/10.1029/2024JA033446","url":null,"abstract":"<p>Magnetic reconnection often initiates abruptly and then rapidly progresses to a nonlinear quasi-steady state. While satellites frequently detect reconnection events, ascertaining whether the system has achieved steady-state or is still evolving in time remains challenging. Here, we propose that the relatively rapid opening of the reconnection separatrices within the electron diffusion region serves as an indicator of the growth phase of reconnection. The opening of the separatrices is produced by electron flows diverging away from the neutral line downstream of the X-line and flowing around a dipolarization front. This flow pattern leads to characteristic spatial structures in the electron pressure-strain interaction that could be a useful indicator for the growth phase of a reconnection event. We employ two-dimensional particle-in-cell numerical simulations of anti-parallel magnetic reconnection to validate this prediction. We find that the signature discussed here, alongside traditional reconnection indicators, can serve as a marker of the growth phase. This signature is potentially accessible using multi-spacecraft single-point measurements, such as with NASA's Magnetospheric Multiscale satellites in Earth's magnetotail. Applications to other settings where reconnection occurs are also discussed.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497276","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":"Statistical Analysis of Van Allen Probes-B Observations of Stable Auroral Red Arc Intervals in the Overlap Region Between the Plasmasphere and the Ring Current","authors":"Rei Sugimura,&nbsp;Kazuo Shiokawa,&nbsp;Yoshizumi Miyoshi,&nbsp;Charles Smith,&nbsp;Harlan Spence,&nbsp;Geoff Reeves","doi":"10.1029/2024JA032893","DOIUrl":"https://doi.org/10.1029/2024JA032893","url":null,"abstract":"<p>In Earth's inner magnetosphere low-energy-density plasma in the plasmasphere (PS) partially overlaps with higher-energy plasma in the ring current (RC). Auroral emissions with zonally elongated arc-like shapes called Stable Auroral Red (SAR) arcs occur in the subauroral latitudes that are connected to the inner magnetosphere. There has yet to be a statistical analysis of the PS-RC overlap region in which SAR arcs occur. We conducted a statistical analysis of the occurrence characteristics of this PS-RC overlap region for SAR arcs, using the RBSP-B satellite over a 4-year period from 1 January 2015 to 31 December 2018. We defined the PS-RC overlap region based on ground-satellite conjugate observations of SAR arcs on the same geomagnetic field line. The overlap region in which SAR arcs develop is located at pre-midnight for high-energy oxygen ions and post-midnight for low-energy hydrogen ions. Superposed epoch analysis using the SYM-H index shows that the PS-RC overlap occurs near the end of the main phase of magnetic storms for both H⁺ and O⁺ ions, indicating that the SAR arc source develops at the particle injection during the end of the storm's main phase. Superposed epoch analysis using the SML index revealed that several substorms occurred near the onset time of the SAR arc source for both ion species. This suggests that particle injection by substorms at the end of the magnetic storm is important for the formation of the SAR arc source.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032893","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497275","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}