Journal of Geophysical Research: Space Physics最新文献

{"title":"Large-Amplitude ExB Plasma Drifts in the High-Latitude Ionosphere","authors":"H. Laakso,&nbsp;R. Pfaff","doi":"10.1029/2025JA034241","DOIUrl":"https://doi.org/10.1029/2025JA034241","url":null,"abstract":"<p>We investigate the fastest ExB plasma drifts observed by the Vector Electric Field Instrument double probe experiment on the NASA's Dynamics Explorer-2 (DE-2) satellite. In the limited DE-2 database, we find 507 events where the zonal ExB velocity exceeds 4 km/s, in which for 91 events the velocity exceeds 6 km/s and 16 events where the drifts are greater than 8 km/s. One primary group of fast drifts consists of nightside events that occur mostly within the shadowed ionosphere and are related to auroral precipitation (e.g., inverted-V, sub-auroral ion drifts, Alfven waves) driven by magnetospheric processes. Another major group of fast drifts corresponds to dayside events that are often directly driven by the solar wind and can occur within either the sunlit or shadowed ionosphere. The fast drifts are observed at all DE-2 altitudes between 300 and 1,000 km with no altitude dependence on the drift velocity. They are generally observed at all MLT sectors although there appears to be a dawn-dusk asymmetry with the fewest events around 15 MLT. In contrast, the occurrence peaks between 6 and 12 MLT. The events occur in the auroral and sub-auroral altitudes, normally between 60 and 83° of invariant latitude, although in the pre-midnight sector, events are found as low as 50° of invariant latitude, corresponding to sub-auroral ion drift (SAID) events. Surprisingly, with the exception of SAID events, the fast drift events occur during all geomagnetic conditions with the velocities showing no dependence on geomagnetic activity.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034241","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145146624","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":"Severe Weather-Generated Acoustic and Gravity Wave Impacts on the Ionosphere: A Model-Guided Case Study","authors":"P. A. Inchin,&nbsp;C. Heale,&nbsp;M. D. Zettergren,&nbsp;B. Bergsson,&nbsp;S. Debchoudhury,&nbsp;S. Chakraborty","doi":"10.1029/2025JA034012","DOIUrl":"https://doi.org/10.1029/2025JA034012","url":null,"abstract":"<p>Acoustic and gravity waves (AGWs) generated by tropospheric weather are known sources of fluctuations in the ionosphere—traveling ionospheric disturbances (TIDs). Despite their importance, the effects of AGWs on the ionosphere, including associated energy and momentum deposition, remain poorly quantified. To address this gap, we present our first three-dimensional numerical simulations of coupled atmosphere-ionosphere dynamics during a typical severe terrestrial weather episode over the continental United States in May 2017. Using the nonlinear compressible models MAGIC and GEMINI, we reproduced many of the salient features of AGW-driven TIDs in slant total electron content. Simulation results reveal that although AGW-TID amplitudes reach only <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>0.35 TECu (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>2–3<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> $%$</annotation>\u0000 </semantics></math> of absolute vTEC), AGWs induce substantial ionospheric fluctuations, up to 70 K in ion and 120 K in electron temperatures (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>10–16<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> $%$</annotation>\u0000 </semantics></math> of ambient state), as well as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>10</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> ${sim} 10%$</annotation>\u0000 </semantics></math> in electron density at 100–300 km altitudes. Furthermore, long-period AGW impacts (lasting several hours), continuously generated by the evolving weather system, result in significant redistribution of plasma and modification of electron density ambient state by more than <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>20</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> ${sim} 20%$</annotation>\u0000 </semantics></math> in the E and bottom F regions of the ionosphere. These modifications can plausibly affect various communication and navigation system applications, highlighting the need to incorporate AGW effects into space weather forecasts.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145146883","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":"Daytime Thermospheric Wind Transients and Circulation in May 2021","authors":"Thomas J. Immel,&nbsp;Lily Oglesby,&nbsp;Brian J. Harding,&nbsp;Astrid Maute,&nbsp;Yen-Jung Wu,&nbsp;Romina Nikoukar,&nbsp;Colin Triplett","doi":"10.1029/2025JA033729","DOIUrl":"https://doi.org/10.1029/2025JA033729","url":null,"abstract":"<p>Changes in the thermospheric wind originating in storm-time transients in high-latitude Joule heating and ion circulation are effective in modifying conditions throughout Earth's upper atmosphere and ionosphere. Among the effects these drivers can produce are large-scale gravity waves (GWs), characterized by significant wind transients that propagate away from the auroral zone, driving transient ion motion during their 1–2 hr passage. Longer period changes in mean winds can develop over the following hours to days, depending on the duration and magnitude of the high latitude heating, and also extend globally. The effectiveness of these processes in modifying the mean density of the daytime ionosphere likely depends on the extent to which these disturbances reach the daytime equatorial region and downward into the E-region wind dynamo (below <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>180 km). A study of a month of observations made during the ICON mission reveals the variety of behaviors with both transient effects and longer-term changes in mean winds. The duration of auroral inputs, as opposed to the average input over time, is identified as important to the development of dynamo-modifying zonal disturbance winds. During geomagnetic disturbances, we find that the predictive capability of a general circulation model (TIEGCM) for meridional wind transport is good (R <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math> .8) while the storm-time zonal wind transport is harder to predict (R <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math> .5). This study is the first of its kind, measuring winds and storm responses continuously for a month in both the daytime E- and F- regions simultaneously with <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>97 min cadence.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033729","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135641","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":"Response of Ionospheric Total Electron Content to the Impulsive and Late Phases of X-Class Solar Flares With Various Center-to-Limb Locations","authors":"S. Z. Bekker,&nbsp;R. O. Milligan,&nbsp;I. A. Ryakhovsky","doi":"10.1029/2025JA034281","DOIUrl":"https://doi.org/10.1029/2025JA034281","url":null,"abstract":"<p>During a solar flare, the fluxes in various lines and continua of the solar spectrum increase, leading to enhanced ionization of the illuminated part of the Earth's ionosphere and an increase in the total electron content (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>T</mi>\u0000 <mi>E</mi>\u0000 <mi>C</mi>\u0000 </mrow>\u0000 <annotation> $TEC$</annotation>\u0000 </semantics></math>). It has been previously shown that nearly 50% of X-class solar flares exhibit a second peak in warm coronal lines, such as Fe XV and Fe XVI, (called the “EUV late phase”) the effect of which on the ionosphere remains largely unexplored. This study presents an analysis of the ionospheric response to 14 X-class flares with pronounced late phases. For the first time, empirical relationships between the increase in <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>T</mi>\u0000 <mi>E</mi>\u0000 <mi>C</mi>\u0000 </mrow>\u0000 <annotation> $TEC$</annotation>\u0000 </semantics></math> and the solar flux enhancement during the impulsive and late phases of the flare are derived. Additionally, we demonstrate the influence of flare location on the intensity of geoeffective solar spectral lines and the ratio of the ionospheric responses to the impulsive and late phases of solar flares.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135735","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":"Penetrating Solar Wind Protons as a Source of Hydrogen to the Martian Atmosphere","authors":"M. L. Sorgi Johann,&nbsp;R. J. Lillis,&nbsp;R. D. Jolitz,&nbsp;J. S. Halekas","doi":"10.1029/2024JA033149","DOIUrl":"https://doi.org/10.1029/2024JA033149","url":null,"abstract":"<p>The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has observed a proton population in the upper Martian atmosphere with plasma velocities and temperatures consistent with the upstream solar wind. This population is believed to originate from solar wind protons that undergo charge exchange with neutral hydrogen in the exosphere, becoming energetic neutral atoms (ENAs) that then penetrate the atmosphere, unaffected by magnetic fields. As these ENAs precipitate, their charge state evolves through subsequent interactions, ultimately depositing as neutral hydrogen. We investigate this deposition process and its variability by combining model predictions with observations of the charged population measured by the Solar Wind Ion Analyzer onboard MAVEN. A Monte Carlo transport model was employed to simulate the competing processes of deposition and backscattering under a range of exospheric and solar wind conditions. Our results show that solar wind hydrogen absorption can exceed <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>25</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{25}$</annotation>\u0000 </semantics></math> <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>s</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{s}}^{-1}$</annotation>\u0000 </semantics></math> at the current epoch, representing 10%–20% of the total hydrogen escape from Mars. This absorption mechanism likely played a significant role in shaping the early Martian atmosphere and climate, when solar wind proton densities were substantially higher.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135741","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":"Accurate Spectral Fitting in the Upper F-Region Using the Randomly Coded Data of the Arecibo 430 MHz Radar","authors":"Yanlin Li,&nbsp;Qihou Zhou","doi":"10.1029/2025JA033877","DOIUrl":"https://doi.org/10.1029/2025JA033877","url":null,"abstract":"<p>Accurately resolving the ion composition in the upper F2 region and topside ionosphere remains a challenge due to temperature-composition ambiguity and measurement limitations. This study presents a hybrid fitting algorithm that combines exhaustive dictionary search with gradient descent to improve the estimation of incoherent scatter spectrum parameters, particularly He⁺ and H⁺ fractions, ion temperature (<i>T</i>_<i>i</i>), and electron temperature (<i>T</i>_<i>e</i>). The algorithm performs independent height-based fitting while incorporating constraints on <i>T</i>_<i>e</i> and <i>T</i>_<i>i</i> to enhance stability. We apply the method to Arecibo incoherent scatter radar coded-long-pulse (CLP) data to demonstrate its effectiveness. To improve the fitting results, we employ an adaptive thresholding method to reduce the interference from satellites and space debris and allow negative He⁺ concentration to mitigate fitting biases. With various factors considered, we show that parameter estimations, especially H⁺ and He⁺ fractions, can be significantly improved. Comparisons with multi-radar autocorrelation function results further validate our improvements in accuracy and consistency. Although the CLP program was initiated at Arecibo decades ago, this is the first time that the data has been used to derive light ion fractions. This study provides a more robust framework for aeronomy studies in the upper F region.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033877","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135740","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":"Whistler-Mode Waves Observed in the Martian Ionosphere","authors":"Xiao Ma,&nbsp;Anmin Tian,&nbsp;Shichen Bai,&nbsp;Ruilong Guo,&nbsp;Jong-Sun Park,&nbsp;Alexander William Degeling,&nbsp;Quanqi Shi,&nbsp;Qiugang Zong,&nbsp;Zhaoguo He","doi":"10.1029/2025JA034177","DOIUrl":"https://doi.org/10.1029/2025JA034177","url":null,"abstract":"<p>It is well-established that whistler-mode waves can play a fundamental role in mediating energy transfer through wave-particle interactions in planetary magnetospheres. In this study, we present in situ observations of whistler-mode waves within the Martian ionosphere using the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft measurements. We find that these emissions are associated with the solar wind electron penetration along open field lines, which is characterized by the pronounced distribution of one-sided loss cones in the outward direction for hot (<i>E</i> &gt; 50 eV) electron fluxes. Analyses of wave instability show that these anisotropic electrons can serve as the primary free energy source for substantial local wave amplification through cyclotron resonance. Our findings reveal that the Martian ionosphere with relatively weak magnetic fields and solar wind intrusions facilitates the local wave excitation. The results of this study provide new insights into wave-particle interactions on unmagnetized planets.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135742","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":"Searching for Universality of Turbulence in the Earth's Magnetosphere","authors":"Dariusz Wójcik,&nbsp;Wiesław M. Macek","doi":"10.1029/2025JA034020","DOIUrl":"https://doi.org/10.1029/2025JA034020","url":null,"abstract":"<p>Turbulence in space plasmas remains a fundamental challenge, and Earth's magnetosphere (MSP) offers a natural laboratory for its study. Using high-resolution magnetic field data from the <i>Magnetospheric Multiscale</i> (<i>MMS</i>) mission, we extend a stochastic Markovian framework to analyze turbulence across 10 diverse magnetospheric regions, including key reconnection sites. We show that magnetic field fluctuations are well described as Markov processes in scale across the kinetic domain. Multi-scale conditional Probability Density Functions (PDFs) reveal Markovian properties beyond the Einstein-Markov scale. The Kramers-Moyal coefficients display linear and quadratic dependencies, and the Fokker-Planck equation accurately reproduces empirical conditional PDFs, with stationary solutions matching observed Kappa distributions. Scale invariance, characterized by power-law behavior and self-similar PDFs, holds up to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>0.4</mn>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> ${sim} 0.4$</annotation>\u0000 </semantics></math> s in most regions but breaks in day-side reconnection jets. These findings support the universality of the Markovian cascade description across the magnetosphere, while identifying region-specific deviations that reflect differing energy dissipation mechanisms.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135633","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":"Hectometric Continuum Radiation Observations on Different Temporal Scales in Near-Earth Space","authors":"D. A. Dorofeev,&nbsp;A. A. Chernyshov,&nbsp;M. M. Mogilevsky,&nbsp;D. V. Chugunin","doi":"10.1029/2025JA033900","DOIUrl":"https://doi.org/10.1029/2025JA033900","url":null,"abstract":"<p>This study analyzes data from the ERG (Arase) satellite over a period of nearly 7 years (2017–2023). During this time, about 1,000 cases of hectometric continuum (HMC) radiation in near-Earth space were detected, which made it possible to identify characteristic features on different time scales. On a daily scale, it was established that HMC is observed at night and is completely absent during the day. There is also an asymmetric shift (different delay before the end and start of HMC generation during sunrise and sunset, respectively) of 1–3 hr relative to sunrise and sunset. Most likely, this is due to the fact that at night, when there is no solar radiation and the plasma density in the upper ionosphere is reduced, HMC is generated. On larger scales, seasonal and annual variations in HMC were detected. A predominance of HMC cases was observed during the summer months, with the fewest cases occurring during the autumn and spring equinoxes. In addition, starting from the second half of 2022, the HMC ceased to be observed, which may be associated with the approach to the peak of the 25th solar activity cycle, as indicated by the increase in the F10.7 index, Wolf numbers and Lyman-alpha radiation, which traditionally characterize solar activity.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135736","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":"Dependence of Low-Frequency Plasmaspheric Hiss on Geomagnetic Activity and Solar Wind Dynamic Pressure and Its Electron Scattering Effects","authors":"Shuqin Chen,&nbsp;Xin Ma,&nbsp;Binbin Ni,&nbsp;Yuequn Lou,&nbsp;Zheng Xiang,&nbsp;Qi Zhu,&nbsp;Taifeng Jin","doi":"10.1029/2025JA034019","DOIUrl":"10.1029/2025JA034019","url":null,"abstract":"<p>Plasmaspheric hiss plays a crucial role in shaping the structure and dynamics of Earth's radiation belts. It's also recognized that low-frequency hiss has characteristics and excitation mechanisms quite different from those of typical normal-frequency hiss. Using high-quality data from Van Allen Probe A between September 2012 and March 2019, we conduct a comprehensive statistical analysis of the global distribution of low-frequency hiss. We investigate the global morphology of low-frequency hiss concerning different conditions of geomagnetic activity and solar wind dynamic pressure (<i>P</i>_dyn). The results reveal significant differences in the global distributions of wave amplitude and occurrence rate between low-frequency hiss and broad-band hiss, particularly in their <i>L</i>-shell distributions. Large-amplitude low-frequency hiss is primarily observed on the afternoon side with <i>L</i> &gt; 5 shifting toward the noonside as the geomagnetic activity intensifies. Furthermore, both the amplitude and occurrence rate of low-frequency hiss decrease with increasing <i>P</i>_dyn, and the occurrence rate exhibits a north-south asymmetry with strong <i>P</i>_dyn. The spectral analysis indicates that the peak frequency of the low-frequency hiss is ∼50 Hz, remaining almost constant with increasing <i>L</i>-shell. Evaluations of hiss-induced electron scattering effects show that the electron resonant energies and scattering rates by low-frequency hiss are significantly different from those by broad-band hiss. Low-frequency hiss has a higher minimum electron resonance energy and larger scattering rates over most of the pitch angle range. Our results are valuable in complementing the existing global distribution model of plasmaspheric hiss and providing an improved understanding of its essential contributions to the radiation belt electron dynamics.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 9","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145146362","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}