Journal of Geophysical Research: Space Physics最新文献

{"title":"Energetic Electron Precipitation From the Radiation Belts: Geomagnetic and Solar Wind Proxies for Precipitation Flux Magnitudes","authors":"Malcolm Crack,&nbsp;Craig J. Rodger,&nbsp;Mark A. Clilverd,&nbsp;Aaron T. Hendry,&nbsp;Jean-Andre Sauvaud","doi":"10.1029/2024JA033158","DOIUrl":"https://doi.org/10.1029/2024JA033158","url":null,"abstract":"<p>Previously the geomagnetic Ap index has been used as a proxy to produce empirical energetic electron precipitation (EEP) forcing representations suitable for incorporation into coupled-climate model runs. The long-running Ap index has the advantage that it allows descriptions of EEP to be made for periods outside the current satellite era, but its suitability has not been checked against other reasonable proxies. In this study three different satellite electron precipitation data sets (DEMETER, POES, and SAMPEX) are used to examine the suitability of a variety of geomagnetic and solar wind proxies to represent EEP flux in different energy ranges. Analysis was undertaken using indices at their fundamental timescales (typically minutes or hours). For medium energy electron precipitation (i.e., &gt;100 keV), the best proxy is found to be either Ap or Dst. For relativistic energy electron precipitation (i.e., &gt;700 keV), the best proxy is Kp or AE, the latter suggesting a connection to substorm activity. The identification of the Ap index as one of the best proxies for medium energy EEP supports the approach taken by van de Kamp et al. (2016), https://doi.org/10.1002/2015jd024212. An EEP forcing capability based on Ap was developed by those authors for inclusion as a solar forcing factor in the Coupled Model Intercomparison Project Phase 6 of the World Climate Research Program.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033158","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533291","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":"Topside Low-Latitude Ionospheric Response to the 10–11 May 2024 Super Geomagnetic Storm as Observed by Swarm: The Strongest Storm-Time Super-Fountain During the Swarm Era?","authors":"Chinmaya Nayak,&nbsp;Stephan Buchert,&nbsp;Erdal Yiğit,&nbsp;M. Ankita,&nbsp;Satyavir Singh,&nbsp;S. Tulasi Ram,&nbsp;A. P. Dimri","doi":"10.1029/2024JA033340","DOIUrl":"https://doi.org/10.1029/2024JA033340","url":null,"abstract":"<p>The current study explores how the topside equatorial and low-latitude ionosphere responded to the super geomagnetic storm on 10–11 May 2024, using in situ data from the Swarm constellation. During the storm's main phase, enhancements in the EIA (equatorial ionization anomaly) were observed, forming strong super-fountains. The EIAs were extended toward latitudes beyond <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 <mn>30</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $pm 30{}^{circ}$</annotation>\u0000 </semantics></math> of the magnetic equator, with the crests of the EIAs being shifted to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>25</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 25{}^{circ}$</annotation>\u0000 </semantics></math> of the magnetic equator on both hemispheres during the main phase of the storm. Swarm-A observed the strongest storm-time super-fountain during its entire age (2013-present) with nearly <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>500</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> $500%$</annotation>\u0000 </semantics></math> increase in the crest density compared to the quiet-time conditions. During the recovery phase, the EIA was suppressed entirely, and density crests were observed over the magnetic equator, and troughs were observed at locations around <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>10</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 10{}^{circ}$</annotation>\u0000 </semantics></math>–<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>15</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $15{}^{circ}$</annotation>\u0000 </semantics></math> of magnetic dip latitude.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533294","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":"Was the Unseasonal Development of Post-Sunset Equatorial Plasma Bubbles in Southeast Asia Driven by Quasi-2-Day Planetary Waves?","authors":"Guofeng Dai,&nbsp;Guozhu Li,&nbsp;Yuichi Otsuka,&nbsp;Lianhuan Hu,&nbsp;Wenjie Sun,&nbsp;Baiqi Ning,&nbsp;Donghe Zhang,&nbsp;Jiuhou Lei,&nbsp;Haiyong Xie,&nbsp;Xiukuan Zhao,&nbsp;Michi Nishioka,&nbsp;Septi Perwitasari,&nbsp;Punyawi Jamjareegulgarn,&nbsp;Yi Li,&nbsp;Chunxiao Yan","doi":"10.1029/2024JA033280","DOIUrl":"https://doi.org/10.1029/2024JA033280","url":null,"abstract":"<p>Previous studies suggest that the planetary waves in mesosphere and low thermosphere (MLT) could modulate the occurrence of equatorial plasma bubbles (EPBs) via altering post-sunset <i>F</i> layer height. Using simultaneous observations by Global Navigation Satellite System receiver networks, two ionosondes separated by about 10° in longitude, high frequency and very high frequency radars, we investigated the day-to-day variations of post-sunset <i>F</i> layer height and EPB occurrence in southeast Asia during the quasi-2-day planetary wave (QTDW) event in July 2023. The results showed that the post-sunset <i>F</i> layer height over Bac Lieu (9.3°N, 105.7°E) and EPB occurrence had a quasi-2-day (QTD) variation. However, such a 2 day variation of <i>F</i> layer height was confined in a very limited longitude, that is contradictory to the planetary scale characteristics of QTDW. We suggest that the QTD variations of post-sunset <i>F</i> layer height and EPB occurrence over the specific location were not necessarily due to the QTDW in MLT. The local seeding source, as characterized by satellite traces in ionosonde ionograms, could drive the small-scale longitudinal structure of <i>F</i> layer height and play an important role in shaping the QTD variation of EPB. The results implicate that the connection between planetary waves and the EPB occurrence over a specific location should be interpreted carefully, even if the day-to-day variation of post-sunset <i>F</i> layer height shows periodic behavior with planetary wave scale.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143533293","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":"Preface to the Special Section on Substorm Research","authors":"Xu-Zhi Zhou,&nbsp;David G. Sibeck,&nbsp;Larry R. Lyons,&nbsp;Akimasa Ieda,&nbsp;Zuyin Pu","doi":"10.1029/2025JA033859","DOIUrl":"https://doi.org/10.1029/2025JA033859","url":null,"abstract":"<p>During the week of 16–20 October 2023, the 15th International Conference on Substorms (ICS-15) was held in the city of Deqing, on the scenic foothill of Mount Mogan in Zhejiang, China. Nearly 100 scientists around the world participated in the meeting, either in-person or online. The conference featured 59 oral presentations, including four 50-min tutorial lectures, and 14 poster presentations. Following the convention of the ICS conference series, participants were invited to submit their studies to a special collection of papers. Submissions from the broader space physics community, even if not participating in the conference, were also encouraged. All the articles in the special collection have undergone a rigorous peer-review process before their publication in either <i>Journal of Geophysical Research Space Physics</i> or <i>Geophysical Research Letters</i>.</p><p>This collection, like the conference itself, covers a wide spectrum of topics related to substorm dynamics. There are articles discussing the enduring question of substorm event sequence and triggering mechanisms, which also involve the identification of substorms from various aspects. The roles of meso-scale flows and associated electromagnetic structures in the substorm dynamics constitute another topic of broad interest, which also contributes to the coupling between magnetotail and ionosphere/thermosphere. Another interesting topic is the consequence of substorm injections in the inner magnetosphere, including the excitation of plasma waves and the acceleration of radiation belt electrons. Finally, there are a few articles focusing on geomagnetic storms and their relationship with substorms, and a few articles on subauroral physics related to STEVE (Strong Thermal Emission Velocity Enhancement).</p><p>While it is still challenging to reach a consensus on every aspect of substorm research, we believe that the advancements in observational capabilities have provided unprecedented opportunities for us to study the substorm-associated phenomena across multiple scales. Many studies in this collection utilize data from multiple sources, from in-situ spacecraft observations to ground-based auroral imagers, magnetometers and radar networks, to refine current models and improve our understanding of the nature of substorms.</p><p>Finally, we would like to thank the conference organizers, the Chinese Society of Space Research and Peking University, for their support to make the ICS-15 meeting possible. We are also grateful to all the meeting attendees for their contributions and lively discussions throughout the meeting, and to the AGU editors, editorial staffs, reviewers and authors who made this collection a reality.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033859","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143530258","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":"Dynamics of Ultra-Relativistic Electrons on 19 December 2015: Combinations of Adiabatic and Non-Adiabatic Effects","authors":"Xiaoyu Wang,&nbsp;Dedong Wang,&nbsp;Xing Cao,&nbsp;Binbin Ni,&nbsp;Alexander Y. Drozdov,&nbsp;Xiaojia Zhang,&nbsp;Xiankang Dou,&nbsp;Yuri Y. Shprits","doi":"10.1029/2024JA033595","DOIUrl":"https://doi.org/10.1029/2024JA033595","url":null,"abstract":"<p>Due to solar wind-magnetosphere coupling, energetic electron fluxes in the outer radiation belt are profoundly influenced by enhanced solar activities. Utilizing observations from Van Allen Probes (VAPs) and low Earth orbit MetOp-02, here we report a case study of dramatic pitch-angle dependent dynamics of ultra-relativistic electrons from 19 to 20 December 2015. We focus on two orbits of VAPs, which contains two successive interplanetary shocks in the first orbit and then storm main phase in the second orbit. Consequently, the ultra-relativistic electron fluxes exhibit around 90°-peaked distributions at <i>L</i>* &gt; 5 in dayside magnetosphere right after each shock, followed by dropouts at almost all pitch angles throughout the outer radiation belt. Electron phase space density (PSD) profiles show that adiabatic effects contribute to the accelerations at high pitch angles (&gt;∼45°) and <i>L</i>* &gt; 5 for both shocks while inward radial diffusion driven by ULF waves plays a dominant role at lower <i>L</i>* after the second shock. Additionally, interactions between concurrent EMIC waves and electrons result in the dropouts at low pitch angles (&lt;∼45°) after each shock. Furthermore, conjugate precipitation after the first shock provides sufficient evidence for EMIC-induced loss. Our results also show that the dropouts in the second orbit are attributed to a combination of magnetopause shadowing effect at <i>L</i>* &gt; 5 and EMIC-driven loss at <i>L</i>* &lt; 4. Our study provides direct observational evidence that combinations of multi-mechanisms, including adiabatic and non-adiabatic effects, result in the dramatic dynamics of ultra-relativistic electrons within one day.</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/10.1029/2024JA033595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143521877","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":"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}