Journal of Geophysical Research: Space Physics最新文献

{"title":"Statistical Characterization of Joule Heating Associated With Ionospheric ULF Perturbations Using SuperDARN Data","authors":"Xueling Shi,&nbsp;Shibaji Chakraborty,&nbsp;Joseph B. H. Baker,&nbsp;Michael D. Hartinger,&nbsp;Wenbin Wang,&nbsp;J. Michael Ruohoniemi,&nbsp;Dong Lin,&nbsp;William Lotko,&nbsp;Kevin Sterne,&nbsp;Kathryn A. McWilliams","doi":"10.1029/2024JA033452","DOIUrl":"https://doi.org/10.1029/2024JA033452","url":null,"abstract":"<p>Ultra low frequency (ULF; 1 mHz - several Hz) waves are key to energy transport within the geospace system, yet their contribution to Joule heating in the upper atmosphere remains poorly quantified. This study statistically examines Joule heating associated with ionospheric ULF perturbations using Super Dual Auroral Radar Network (SuperDARN) data spanning middle to polar latitudes. Our analysis utilizes high-time-resolution measurements from SuperDARN high-frequency coherent scatter radars operating in a special mode, sampling three “camping beams” approximately every 18 s. We focus on ULF perturbations within the Pc5 frequency range (1.6–6.7 mHz), estimating Joule heating rates from ionospheric electric fields derived from SuperDARN data and height-integrated Pedersen conductance from empirical models. The analysis includes statistical characterization of Pc5 wave occurrence, electric fields, Joule heating rates, and azimuthal wave numbers. Our results reveal enhanced electric fields and Joule heating rates in the morning and pre-midnight sectors, even though Pc5 wave occurrences peak in the afternoon. Joule heating is more pronounced in the high-latitude morning sector during northward interplanetary magnetic field conditions, attributed to local time asymmetry in Pedersen conductance and Pc5 waves driven by Kelvin-Helmholtz instability. Pc5 waves observed by multiple camping beams predominantly propagate westward at low azimuthal wave numbers <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mo>|</mo>\u0000 <mi>m</mi>\u0000 <mo>|</mo>\u0000 <mo>&lt;</mo>\u0000 <mn>50</mn>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(vert mvert &lt; 50)$</annotation>\u0000 </semantics></math>, while high-m waves propagate mainly eastward. Although Joule heating estimates may be underestimated due to assumptions about empirical conductance models and the underestimation of electric fields resulting from SuperDARN line-of-sight velocity measurements, these findings offer valuable insights into ULF wave-related energy dissipation in the geospace system.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033452","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Sudden Stratospheric Warming and Elevated Stratopause Events on the Very Low Frequency Radio Signal","authors":"H. Schneider,&nbsp;V. Wendt,&nbsp;D. Banyś,&nbsp;M. Hansen,&nbsp;M. Clilverd,&nbsp;P. T. Verronen","doi":"10.1029/2024JA033320","DOIUrl":"https://doi.org/10.1029/2024JA033320","url":null,"abstract":"<p>Sudden Stratospheric Warmings (SSW) and Elevated Stratopause (ES) events are mid-to-high latitudinal, atmospheric wave-driven phenomena leading to significant changes in wind, temperatures, and vertical mass transport, especially at stratospheric and mesospheric altitudes. Presumably, SSW and ES-induced changes also cause modifications in the highly variable D-region ionization. This bottom side of the ionosphere behaves with the Earth's surface as a reflection boundary for Very Low Frequency (VLF) radio signal transmission used for long-distance communication. Since perturbations of the D-region ionization are also notable in the VLF signal, it is a valuable tool for continuous investigations of the D-region. Here, we study the impact of four SSW/ES events on the VLF signal amplitude between the high latitude transmitter-receiver link Keflavik, Iceland, to Ny-Ålesund, Svalbard, to gain further knowledge about interactions between the D-region and the atmosphere during these atmospheric phenomena. For three of four SSW/ES events, a very similar VLF signal amplitude signature is observed, characterized by a significant increase during the SSW period in the signal amplitude followed by a decrease during the ES period. This study aims to reveal a possible mechanism driving these similar VLF signal amplitude variations, involving modified electron neutral collision frequencies and electron densities due to changed temperatures and minor constituent concentrations according to the SSW/ES events. However, the VLF signal amplitude for one event increased 2 weeks later than during the other three events and did not show a decrease during the ES period. Possible causes for the different VLF signal amplitude variations are discussed.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033320","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639062","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":"Responses of the Daytime Low and Equatorial Ionosphere and Thermosphere Over the Indian Region During the Geomagnetic Storm of April 2023","authors":"Lalitha G. Krishnan,&nbsp;Kazuo Shiokawa,&nbsp;Tarun Kumar Pant,&nbsp;Gang Lu,&nbsp;P. R. Shreedevi,&nbsp;Yuichi Otsuka,&nbsp;Surendra Sunda","doi":"10.1029/2024JA033141","DOIUrl":"https://doi.org/10.1029/2024JA033141","url":null,"abstract":"<p>Study of the response of Thermosphere–Ionosphere (TI) system over the Indian longitude sector during the geomagnetic storm of April 23–24, 2023, is presented. The ionosonde observations at the dip equatorial station, Trivandrum (8.52°N, 77°E, dip lat. = 1.96°N), are found to have unusually high F2 peak plasma density (foF2), with three maxima during the daytime on April 24. The Total Electron Content (TEC) observations from different latitudes showed enhancements temporally progressing from north to south. These features are identified as Traveling Ionospheric Disturbances (TIDs) with speeds ∼400 to 750 m/s. Two major enhancements in TEC observed over Trivandrum were concurrent to the first and third maxima in foF2. Simulations of meridional wind and temperature for this storm were carried out using the Thermosphere–Ionosphere–Electrodynamics General Circulation Model (TIEGCM) that was driven with high-latitude inputs derived from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique. Simulations show the signatures of Traveling Atmospheric Disturbances (TADs) in ionospheric F-region, which conform with the TID observations. The second foF2 peak is found to be simultaneous to the modulation in Prompt Penetration Electric Field (PPEF), which is also observed in the drift of the E-region ionospheric plasma irregularities using an HF radar and the Equatorial Electrojet (EEJ) strength measured by ground-based magnetometer. Simultaneously increasing electric field and foF2 implies the presence of storm-time equatorward wind, inhibiting the plasma fountain. This is the first report comparing comprehensive observations and AMIE-TIEGCM modeling studies of daytime responses of low and equatorial TI during a geomagnetic storm.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639061","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":"Nonlinear Dynamics and Auroral Acceleration Processes of Electrons Driven by Kinetic Alfvén Waves in the Magnetosphere","authors":"Koseki Saito,&nbsp;Yuto Katoh,&nbsp;Yohei Kawazura,&nbsp;Atsushi Kumamoto","doi":"10.1029/2024JA033469","DOIUrl":"https://doi.org/10.1029/2024JA033469","url":null,"abstract":"<p>This study investigates the nonlinear Landau resonance and auroral acceleration processes of electrons driven by kinetic Alfvén waves (KAWs) in the Earth's magnetosphere. We analyze electron trajectories and parameters, such as kinetic energy, using test particle simulations, focusing on the transition between phase-trapped and phase-scattered states induced by magnetic field gradients. Based on the second-order resonance theory, we define the conditions under which electrons are either trapped or non-trapped by the KAWs. Our key findings are: (a) Electrons can be significantly accelerated not only when they are trapped by the waves and transported toward the ionosphere, but also in the detrapped state; (b) Even with monochromatic KAWs, the energy of electrons in the ionosphere depends on their state at the moment they are detrapped from the KAWs; (c) The dynamics of phase-scattered electrons affect the efficiency of electron acceleration processes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033469","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632887","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":"Statistical Properties of Short Large-Amplitude Magnetic Structures (SLAMS) in the Foreshock of Earth From Cluster Measurements","authors":"S. Bergman,&nbsp;T. Karlsson,&nbsp;T. K. Wong Chan,&nbsp;H. Trollvik","doi":"10.1029/2024JA033568","DOIUrl":"https://doi.org/10.1029/2024JA033568","url":null,"abstract":"<p>Short Large-Amplitude Magnetic Structures (SLAMS) are non-linear isolated magnetic field structures commonly observed in the foreshock region of quasi-parallel collisionless shocks. In this work, we use an automated algorithm to create a database of SLAMS detections made in the foreshock of Earth by the Cluster mission between the years 2002–2012. We define SLAMS to have amplitudes of at least two times the background magnetic field, leading to a detection of 1736 SLAMS during the studied period. Subsequently, the statistical properties of the SLAMS in the database are studied, such as their amplitude and temporal scale size. Correlations with the upstream environment are also studied, together with the conditions required for SLAMS formation and solar cycle dependencies. We find a mean temporal scale size of 3.3 s and an amplitude normalized by the background field, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>B</mi>\u0000 <mo>/</mo>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mrow>\u0000 <mi>b</mi>\u0000 <mi>g</mi>\u0000 </mrow>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${Delta }B/{B}_{bg}$</annotation>\u0000 </semantics></math>, varying between 2 and 9, with a mean value of 2.9. 81% of the SLAMS are right-hand polarized in the spacecraft frame. We find that the magnetosonic and Alfvén Mach numbers are important for SLAMS formation, with an increasing observation rate with increasing Mach numbers. Higher Mach numbers also tend to increase <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>B</mi>\u0000 <mo>/</mo>\u0000 <msub>\u0000 <mi>B</mi>\u0000 <mrow>\u0000 <mi>b</mi>\u0000 <mi>g</mi>\u0000 </mrow>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${Delta }B/{B}_{bg}$</annotation>\u0000 </semantics></math> and decrease the temporal scale size of the structures. SLAMS are often associated with peaks in the plasma density, and we find a positive correlation between the amplitude of the magnetic field peaks and the amplitude of the density peaks, confirming the fast magnetosonic nature of SLAMS.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033568","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629896","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 the Short-Range Longitudinal Variation of Pre-Reversal Enhancement of Vertical Plasma Drift and Associated Implications","authors":"A. K. Patra,&nbsp;K. K. Ajith,&nbsp;Septi Perwitasari","doi":"10.1029/2024JA033124","DOIUrl":"https://doi.org/10.1029/2024JA033124","url":null,"abstract":"<p>Pre-reversal enhancement of vertical plasma drift (PRE) is a unique feature of the equatorial ionosphere and plays an important role in defining the state and stability of the evening ionosphere. In this paper, we investigate short-range longitudinal variations of PRE and its consequence on the longitudinal configuration of the equatorial bottomside F layer and the equatorial plasma bubble (EPB) phenomenon. We use simultaneous observations made using three longitudinally separated ionosondes located close to the magnetic equator and spread over a longitude zone of 24° in the Asian sector to study longitudinal variations in the vertical plasma drift, <i>V</i>_<i>z</i> and the height of the F layer base. The peak <i>V</i>_<i>z</i> as well as the temporal pattern of <i>V</i>_<i>z</i> show large longitudinal variations and the maximum difference in the peak <i>V</i>_<i>z</i> between two stations is found to be in the range of 29–49 m s⁻¹, which is remarkable. The large longitudinal difference in <i>V</i>_<i>z</i> is attributed to localized polarization process, which acts additively to the large-scale PRE process. The longitudinal variation in <i>V</i>_<i>z</i> could result in both positive and negative tilt of the F layer base, which is shown to have a considerable role on the growth of the Rayleigh-Taylor instability for the formation of EPB. The plausible origins of longitudinal variation in PRE and its consequences are discussed.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629781","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":"Comparison of Cassini Observations and the JPL SATRAD Model for Determining the Energetic Particle Radiation Environment for Enceladus Missions","authors":"A. Andersen,&nbsp;P. Kollmann,&nbsp;J. M. Ratliff","doi":"10.1029/2024JA033442","DOIUrl":"https://doi.org/10.1029/2024JA033442","url":null,"abstract":"<p>Future missions to Saturn's moon Enceladus will be subjected to a significant trapped radiation environment. The Jet Propulsion Laboratory (JPL) Saturn Radiation (SATRAD) model was developed to estimate the Saturn trapped radiation environment for the Cassini mission. This study compares the long-term averaged electron and proton Cassini data to the predictions of the SATRAD model. High-energy electron data, especially that near Enceladus, agree well with SATRAD, suggesting that SATRAD is useful for providing estimates of the radiation environment for future Enceladus missions. Nevertheless, there are many regions where the data and the model do not agree, demonstrating the need to update the SATRAD model using Cassini data.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622293","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":"Latitudinal Distribution of Thermospheric Nitric Oxide (NO) Infrared Radiative Cooling During May and October 2024 Geomagnetic Storms","authors":"Alok Kumar Ranjan,&nbsp;Duggirala Pallamraju","doi":"10.1029/2024JA033559","DOIUrl":"https://doi.org/10.1029/2024JA033559","url":null,"abstract":"<p>Nitric oxide (NO) radiative cooling, seen as infrared emissions, plays an important role in the energy budget of thermosphere during geomagnetic storms. These emissions serve as a significant heat sink for the thermosphere and facilitate its recovery from the enhanced density and kinetic energy caused by increased Joule heating. Hence, the knowledge of latitudinal distribution of these emissions becomes significant considering the importance of the recovery time duration of the global thermosphere as a consequence of geomagnetic storms. This study discusses the dominating role of storm induced meridional winds, generated due to the Joule heating in the polar regions, in controlling the latitudinal distribution of NO infrared radiative cooling emissions during the two most severe geomagnetic storms of the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>25</mn>\u0000 <mrow>\u0000 <mi>t</mi>\u0000 <mi>h</mi>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $25mathrm{t}mathrm{h}$</annotation>\u0000 </semantics></math> solar cycle (10–11 May, and 10–11 October 2024). During the May 11 event, the peak NO infrared radiative cooling events shifted from the high-latitudes (30–83 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N) to low-latitude (10 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>S–30 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N) regions, whereas for the October 11 event, most of the emissions were located in 30–83 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N, and 0–52 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>S latitude regions. The roles of background seasonal winds, and their associated compositional changes, and the solar energetic radiation (Extreme Ultraviolet <i>or</i> EUV) in modulating the latitudinal variations in the thermospheric NO infrared radiative cooling during both these events, and their consequences for space weather studies are presented.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622515","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":"Effects of Sudden Stratospheric Warming on the Light H and O Species in the Upper Thermosphere","authors":"Changan Wan,&nbsp;Jianqi Qin,&nbsp;Larry J. Paxton","doi":"10.1029/2024JA033243","DOIUrl":"https://doi.org/10.1029/2024JA033243","url":null,"abstract":"<p>Sudden stratospheric warming (SSW) is a significant type of meteorological disturbance that occurs in the winter polar atmosphere. Previous studies have shown that rapid warming of the polar stratosphere can induce electrodynamic and thermodynamic variabilities in the upper atmosphere over the entire globe. However, the effects of SSW on the light neutral species (e.g., H and O) remain poorly understood. Here we report coincident H and O variations in the upper thermosphere during SSW events, based on observations from the Global Ultraviolet Imager (GUVI) on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. The GUVI observations indicate rapid increase of the H abundance and reduction of the O abundance at low latitudes within <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>30</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 30{}^{circ}$</annotation>\u0000 </semantics></math>S–30<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>N in the upper thermosphere (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>200–500 km) following the onset of an Antarctic and an Arctic SSW event that occurred under high solar condition in September 2002 and January 2003, respectively. Moreover, we found that the effects of SSW on the H variations are barely discernible from the GUVI observations that were acquired in 2004–2006 under relatively low solar condition. We used the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCM-X) to simulate the effects of SSW on the H and O abundance. The modeling results under both high and low solar conditions are consistent with the GUVI observations, indicating that solar activity modulates the effects of SSW on vertical coupling between the lower and upper atmosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143622294","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":"Are Supersubstorms Substorms? Extreme Nightside Auroral Electrojet Activities During the May 2024 Geomagnetic Storm","authors":"Ying Zou,&nbsp;Ohtani Shin,&nbsp;Jesper W. Gjerloev,&nbsp;Brian J. Anderson,&nbsp;Colin L. Waters,&nbsp;Chih-Ping Wang,&nbsp;Jun Liang,&nbsp;Larry L. Lyons,&nbsp;Asti Bhatt","doi":"10.1029/2024JA033303","DOIUrl":"https://doi.org/10.1029/2024JA033303","url":null,"abstract":"<p>Enhancement of currents in Earth's ionosphere adversely impacts systems and technologies, and one example of extreme enhancement is supersubstorms. Despite the name, whether a supersubstorm is a substorm remains an open question, because studies suggest that unlike substorms, supersubstorms sometimes affect all local times including the dayside. The spectacular May 2024 storm contains signatures of two supersubstorms that occurred successively in time with similar magnitude and duration, and we explore the nature of them by examining the morphology of the auroral electrojet, the corresponding disturbances in the magnetosphere, and the solar wind driving conditions. The results show that the two events exhibit distinctly different features. The first event was characterized by a locally intensified electrojet followed by a rapid expansion in latitude and local time. Auroral observations showed poleward expansion of auroras (or aurorae), and geosynchronous observations showed thickening of the plasma sheet, magnetic field dipolarization, and energetic particle injections. The second event was characterized by an instantaneous intensification of the electrojet over broad latitude and local time. Auroras did not expand but brightened simultaneously across the sky. Radar and LEO observations showed enhancement of the ionospheric electric field. Therefore, the first event is a substorm, whereas the second event is enhancement of general magnetospheric convection driven by a solar wind pressure increase. These results illustrate that the so-called supersubstorms have more than one type of driver, and that internal instability in the magnetotail and external driving of the solar wind are equally important in driving extreme auroral electrojet activity.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612363","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}