Journal of Geophysical Research: Space Physics最新文献

{"title":"Dynamical Response of the Middle and Upper Atmosphere to the February 2018 Sudden Stratospheric Warming Revealed by MERRA-2 and SABER","authors":"Guiping Liu,&nbsp;Fabrizio Sassi,&nbsp;Ruth S. Lieberman,&nbsp;Lawrence Coy,&nbsp;Steven Pawson","doi":"10.1029/2024JA033528","DOIUrl":"https://doi.org/10.1029/2024JA033528","url":null,"abstract":"<p>The middle and upper atmosphere plays a critical role in linking the lower atmosphere forcing with ionospheric variability, especially during strong atmospheric activities. This study examines the dynamical response in the altitude range from ∼20 to 80 km to a major Sudden Stratospheric Warming (SSW) event peaking on 11 February 2018. We compare the reanalysis product of the Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA-2) from the Goddard Earth Observing System (GEOS) to the satellite observations by Thermosphere Ionosphere and Mesosphere Electric Dynamics (TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) TIMED/SABER that are not assimilated in MERRA-2. Our study shows that the zonal mean wind and temperature and planetary wave 1 and 2 variations are generally consistent between the reanalysis and observations. We also identify a strong ∼6 day wave propagating both westward and eastward with zonal wavenumber-1 with the westward propagating component likely generated by baroclinic/barotropic instability. However, important disagreements arise specifically above ∼60 km, where the wind and temperature are not well represented in MERRA-2, causing differences in the day-to-day development of 6 day wave. This study highlights the need for additional assimilation of mesospheric data and development of high-altitude vertically extended GEOS model.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143741445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effects of Solar Flares and Geomagnetic Storm on the Upper and Lower Ionosphere Across the Malay Archipelago Between 8th and 15th May 2024","authors":"D. J. Ang,&nbsp;S. M. Buhari,&nbsp;M. Abdullah,&nbsp;S. A. Bahari","doi":"10.1029/2024JA033601","DOIUrl":"https://doi.org/10.1029/2024JA033601","url":null,"abstract":"<p>The Mother's Day Storm is the strongest solar storm event in Solar Cycle 25 to date and has been the strongest solar storm since the Halloween storm of 2003. This event provides a great opportunity to investigate the effect of the solar storm on the upper and lower ionospheres. In this study, we investigated the response of the ionosphere to solar flares and geomagnetic storms between 8th and 15th May 2024, using very low frequency radio waves (VLF) collected by our newly built UTM-SID VLF receiver and analyzing the Total Electron Contents (TEC), detrended TEC (dTEC), and Rate Of TEC change Index (ROTI) derived from Global Positioning Satellite System (GNSS) signals across the Malay Archipelago Region. UTM-SID successfully detected 38 out of 114 solar flares that occurred during this period, and the detection depended on the intensity and time of the solar flare. 7 dTEC and 5 ROTI responses were noted, along with a rapid enhancement of vertical TEC (vTEC) of up to 0.5 TECU during severe solar flares. Meanwhile, the geomagnetic storm that occurred on 11–12 May had induced high dTEC and ROTI variations, with dTEC reaching 5 TECU and ROTI of 0.5 TECU/min, suggesting the occurrence of a Travelling Ionospheric Disturbance (TID). Additionally, Equatorial Plasma Bubbles (EPB) were found to be suppressed on 11 May and a pre-sunrise EPB was noted on 12 May. Background VLF signals are also enhanced during this period.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735490","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 Properties of Dayside Whistler-Mode Waves at Low Latitudes Under Various Solar Wind Conditions","authors":"Y. Peng,&nbsp;W. Li,&nbsp;Q. Ma,&nbsp;X.-C. Shen","doi":"10.1029/2024JA033225","DOIUrl":"https://doi.org/10.1029/2024JA033225","url":null,"abstract":"<p>While whistler-mode waves are generated by injected anisotropic electrons on the nightside, the observed day-night asymmetry of wave distributions raises an intriguing question about their generation on the dayside. In this study, we evaluate the distributions of whistler-mode wave amplitudes and electrons as a function of distance from the magnetopause (MP) on the dayside from 6 to 18 hr in magnetic local time (MLT) within ±18° of magnetic latitude using the Time History of Events and Macroscale Interaction During Substorms measurements from June 2010 to August 2018. Specifically, under different levels of solar wind dynamic pressure and geomagnetic index, we conduct a statistical analysis to examine whistler-mode wave amplitude, as well as anisotropy and phase space density (PSD) of source electrons across 1–20 keV energies, which potentially provide a source of free energy for wave generation. In coordinates relative to the MP, we find that lower-band (0.05–0.5 <i>f</i>_ce) waves occur much closer to the MP than upper-band (0.5–0.8 <i>f</i>_ce) waves, where <i>f</i>_ce is electron cyclotron frequency. Our statistical results reveal that strong waves are associated with high anisotropy and high PSD of source electrons near the equator, indicating a preferred region for local wave generation on the dayside. Over 10–14 hr in MLT, as latitude increases, electron anisotropy decreases, while whistler-mode wave amplitudes increase, suggesting that wave propagation from the equator to higher latitudes, along with amplification along the propagation path, is necessary to explain the observed waves on the dayside.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033225","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735491","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":"Variations in the Thermosphere During the 2018 SSW Event at Beijing and Wuhan","authors":"Shaoyang Li,&nbsp;Zhipeng Ren,&nbsp;Tingting Yu,&nbsp;Guozhu Li,&nbsp;Xinan Yue,&nbsp;Libo Liu,&nbsp;Yong Wei,&nbsp;Xing Li","doi":"10.1029/2025JA033767","DOIUrl":"https://doi.org/10.1029/2025JA033767","url":null,"abstract":"<p>Daytime thermospheric responses to the 2018 sudden stratospheric warming (SSW) are investigated in this study. The method proposed by Li et al. (2023), https://doi.org/10.1029/2022ja030988 for deriving exospheric temperature (Tex) from electron density (Ne) profiles was employed. Reliability of this method was verified through comparisons with observations from incoherent scatter radar and the Swarm-C satellite, showing Tex relative deviations within ±2% at most cases. At Beijing, SSW effects manifested as cooling, with a reduction in average Tex by −1–−17 K and average neutral density decreasing by 3%–15% compared to non-SSW. Differently, at Wuhan, SSW effects exhibited semi-diurnal-like variations consistent with previous studies. Average Tex increased by up to 13 and 9 K, and average neutral density increased by up to ∼13% and ∼5% near the dawn and dusk sectors, respectively. Decreases of up to −15 K and ∼−12% were observed near the noon sector. These distinct characteristics, including latitude-dependence and semi-diurnal-like variations, highlight the role of SSW in modulating the thermosphere, providing an opportunity to better understand the vertical coupling between different atmospheric regions.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735527","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":"A Simulation Study of NmF2 Semiannual Anomaly at the Zhongshan Station, Antarctica, at Solar Maximum Based on TIEGCM","authors":"Qing-Yu Zhang,&nbsp;Bei-Chen Zhang,&nbsp;Qing-He Zhang,&nbsp;Xiang-Cai Chen,&nbsp;Zan-Yang Xing,&nbsp;Yong Wang,&nbsp;Yu-Zhang Ma,&nbsp;Sheng Lu","doi":"10.1029/2024JA032907","DOIUrl":"https://doi.org/10.1029/2024JA032907","url":null,"abstract":"<p>The semiannual anomaly, characterized by increased peak electron density in the F2 layer (NmF2) at equinoxes compared to solstices, remains incompletely elucidated, especially at high latitudes. The magnetospheric convection pattern introduces additional complexity to its formation mechanisms. This study utilized the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) to explore the semiannual anomaly at the Zhongshan Station (ZHS), Antarctica, focusing on the processes occurring in the polar upper atmosphere, which are crucial in the formation of this phenomenon. Simulations reveal that the convective electric fields at high latitudes amplify the semiannual variation of NmF2. Specifically, the daytime peak electron density at ZHS is primarily influenced by the availability of ionization sources at middle-high latitudes for convective transport. During the equinox, this peak is enhanced through transport, due to higher plasma density at middle-high latitudes, whereas in summer, there is a depletion of ionization sources at lower latitudes, results in a less efficient transport effect. The semiannual variation in ionization sources is attributed to changes in the neutral composition driven by thermospheric circulation and neutral temperature. Additionally, during the equinox, the coupling of neutral winds with ion convection draws air parcels with larger O/N₂ from lower latitudes, shaping the distribution of neutral composition into a “neutral tongue,” further intensifying the plasma transport effect. These findings provide new insights into the intricate interactions among magnetospheric, ionospheric, and thermospheric dynamics.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735530","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":"Lightning-Induced Electron Precipitation Events Observed at Low Altitudes","authors":"V. Linzmayer,&nbsp;F. Němec,&nbsp;O. Santolík,&nbsp;I. Kolmašová","doi":"10.1029/2024JA033639","DOIUrl":"https://doi.org/10.1029/2024JA033639","url":null,"abstract":"<p>Lightning-induced electron precipitation (LEP) events are important phenomena in the Earth's inner magnetosphere, where atmospheric lightning strokes cause energetic electron loss from the radiation belts. Lightning strokes generate electromagnetic waves that penetrate the ionosphere and propagate through the Earth's magnetosphere as so-called lightning-generated whistlers. They interact with radiation belt electrons, decreasing their pitch angles and causing their eventual loss in the atmosphere. At low altitudes, LEP events in satellite data are characterized by a sudden increase in wave intensity across a wide range of frequencies accompanied by an increase in precipitating electron flux. We detect and analyze LEP events using wave and particle burst mode data measured by the DEMETER satellite between 2004 and 2010. We develop a semi-automatic procedure to identify these events, detecting more than 400 events in total. The identified events mostly occur at L-shells between approximately 2 and 3.75, and extend up to energies of about 200 keV. Most events are detected above the U.S. East Coast, possibly related to significant lightning activity and the location westward of the South Atlantic Anomaly. Finally, we estimate total precipitating electron fluxes and wave intensities based on the average LEP properties and lightning occurrence rate, and we show that the individual isolated LEP events appear to be insufficient to explain the observed summer-winter differences in the precipitating electron fluxes above the U.S. region.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033639","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735528","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":"Effects of Fine Spectral Structure of Chorus Emissions on Nonlinear Scattering and Acceleration of Radiation Belt Electrons","authors":"Miroslav Hanzelka,&nbsp;Yuri Shprits,&nbsp;Dedong Wang,&nbsp;Bernhard Haas,&nbsp;Ondřej Santolík,&nbsp;Longzhi Gan","doi":"10.1029/2024JA033382","DOIUrl":"https://doi.org/10.1029/2024JA033382","url":null,"abstract":"<p>Whistler-mode chorus waves play a crucial role in accelerating electrons in Earth's outer radiation belt to relativistic and ultrarelativistic energies. While this electron evolution is typically modeled using a diffusion approximation for scattering, high-amplitude chorus waves induce nonlinear resonant effects that challenge this approach on short time scales. The long-term influence of these nonlinear interactions on radiation belt dynamics remains an unresolved issue. Recent simplified models suggest rapid nonlinear acceleration to ultrarelativistic energies, with formation of butterfly distributions during parallel wave propagation. In this study, we introduce a novel numerical approach based on Liouville phase space density mapping to investigate nonlinear scattering by high-amplitude waves over extended periods (minutes and beyond). We use a numerical wave field model of lower-band chorus risers that includes realistic fine-spectral features including subpacket modulations, phase decoherence, and jumps in wave normal angle. By incorporating these detailed spectral characteristics of the waves, we demonstrate that the rapid acceleration occurs across a broader pitch-angle range, forming a flat-top distribution. Similar effect is observed as the repetition period of chorus elements becomes shorter, with the additional effect of increased electron precipitation due to transition from bursty to continuous flux profiles in the loss cone. These findings highlight the importance of incorporating nonlinear effects and fine-scale wave properties in the future development of high-energy electron models for the outer radiation belt.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033382","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143735529","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":"Limits on the Efficacy of Wave-Particle Interaction on the Energization and Transport of Atomic and Molecular Heavy Ionospheric Ions","authors":"Mei-Yun Lin,&nbsp;Raluca Ilie,&nbsp;Alex Glocer","doi":"10.1029/2024JA033523","DOIUrl":"https://doi.org/10.1029/2024JA033523","url":null,"abstract":"&lt;p&gt;Ionospheric molecular ions, such as &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}^{+}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, NO&lt;sup&gt;+&lt;/sup&gt;, and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{O}}_{2}^{+}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, have been observed in Earth's high-altitude ionosphere and the magnetosphere by several spacecraft missions. Their presence not only indicates that they obtain sufficient energy through effective energization mechanisms, predominantly during the geomagnetically active times, but also provides clues regarding the connection between the ionosphere and the lower thermosphere. It is, however, unknown to date which physical processes are responsible for the transport and energization of molecular ions, as well as their relative contributions to the plasma surrounding the near-Earth region. In this study, we employ the Seven Ion Polar Wind Outflow Model (7iPWOM) and examine the properties of molecular &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}^{+}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, NO&lt;sup&gt;+&lt;/sup&gt;, and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{O}}_{2}^{+}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; upflows and outflows in response to wave activity. The 7iPWOM is a hybrid polar wind model which solves the transport of e&lt;sup&gt;−&lt;/sup&gt;, H&lt;sup&gt;+&lt;/sup&gt;, He&lt;sup&gt;+&lt;/sup&gt;, N&lt;sup&gt;+&lt;/sup&gt;, O&lt;sup&gt;+&lt;/sup&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;+&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}^{+}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, NO&lt;sup&gt;+&lt;/sup&gt;, and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;O&lt;/mi&gt;\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033523","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143717119","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":"Generation of Perpendicular Ion Acoustic Waves in the Ramp Region of Earth's Bow Shock in the Presence of a Flat-Top Electron Velocity Distribution","authors":"Manpreet Singh,&nbsp;Federico Fraschetti,&nbsp;Joe Giacalone","doi":"10.1029/2025JA033745","DOIUrl":"https://doi.org/10.1029/2025JA033745","url":null,"abstract":"<p>We investigate the generation and stability of ion acoustic waves (IAWs) in the ramp region of perpendicular Earth's bow shock. Using a fluid model, we derive the dispersion relation of IAWs, assuming a flat-top electron velocity distribution function typically observed at interplanetary and Earth's bow shocks, along with jumps in plasma parameters. Our findings show that these electrostatic modes are non-dispersive within the shock ramp, which is in agreement with in-situ observations from the Magnetospheric Multiscale Mission (MMS). The calculated frequencies and phase velocities align closely with MMS measurements. Furthermore, we find that the growth rate of IAWs is more strongly affected by the ion temperature jump across the shock than by the electron temperature jump. The methodology developed in this work can be extended to investigate the generation and stability of other wave modes in diverse space and astrophysical plasma environments.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143726758","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":"Loss Cone Offset Method for Evaluating the Effect of Magnetic Field Line Curvature Scattering (FLCS)","authors":"Ziming Wei,&nbsp;Yiqun Yu,&nbsp;Longxing Ma,&nbsp;Jinbin Cao","doi":"10.1029/2024JA033422","DOIUrl":"https://doi.org/10.1029/2024JA033422","url":null,"abstract":"<p>Magnetic Field Line Curvature Scattering (FLCS) is one of the important loss mechanism for energetic particles, referring to the scattering phenomenon where charged particles experience changes in their pitch angles due to the curvature and non-uniformity of magnetic field. Previous methods evaluating FLCS were suitable for less stretched configurations like dipole magnetic fields, but under Ts05 model, they led to non-physical results, especially in regions where the adiabatic parameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>ε</mi>\u0000 </mrow>\u0000 <annotation> $varepsilon $</annotation>\u0000 </semantics></math> exceeds 0.584. To address this, we developed a new method for evaluating FLCS, named the Loss Cone Offset method (LCOM). The method first anchors the offset of loss cone center due to Borovsky et al. (2022), https://doi.org/10.1029/2021ja030106 and works by constructing the pitch angle offset after one FLCS as a function of initial pitch angle and gyro-phase angle, and then correcting the function by parameters fitting using test-particle-tracing results. Our calculations can effectively evaluate particle scattering due to FLCS in the range of 0°–90° pitch angles and adiabatic parameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>ε</mi>\u0000 </mrow>\u0000 <annotation> $varepsilon $</annotation>\u0000 </semantics></math> ranging from 0.1 to 0.96. Loss Cone Offset method has good compatibility with previous methods under dipole magnetic field or TS05 magnetic field with low adiabatic parameters. It can effectively avoid non-physical results under stretched magnetic field and high adiabatic parameters, and evaluate the FLCS influence. Comparison with theoretical calculations, empirical formulas, and test-particle results demonstrates that the LCOM serves as an easy-to-use and reliable model for predicting particle loss due to FLCS in the magnetospheric dynamics. Its application deepens understanding of FLCS mechanisms, providing robust methodological support for developing physical models.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689613","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}