Journal of Geophysical Research: Space Physics最新文献

{"title":"Winter Enhancement of the Occurrence and Intensity of the Sporadic-E Layer","authors":"Qiong Tang,&nbsp;Yuqiang Zhang,&nbsp;Wenjun Liu,&nbsp;Yiming Wu,&nbsp;Moran Liu,&nbsp;Yi Liu,&nbsp;Chen Zhou","doi":"10.1029/2024JA033695","DOIUrl":"https://doi.org/10.1029/2024JA033695","url":null,"abstract":"<p>In this study, long-term variations in the occurrence rate and intensity of the sporadic-E (Es) layer are investigated using data from the Constellation Observing System for Meteorology Ionosphere and Climate radio occultation and ground-based ionosondes. The results reveal a distinct semiannual variation in Es layer behavior, with a prominent maximum during the summer and a secondary weaker peak during the winter. Additionally, the occurrence rate and intensity of the Es layer reach their minima during the equinoxes, specifically in March/April and September/October. The analysis of quasi-6-day (Q6DW) and quasi-16-day (Q16DW) planetary waves (PWs) in the mesosphere and lower thermosphere region shows notable enhancement during the winter months. This modulation of wind patterns by amplified PWs is suggested to contribute to the winter enhancement of the Es layer. Furthermore, horizontal wind data from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension are used to simulate vertical ion convergence (VIC). The simulation results indicate that VIC peaks in both summer and winter, offering an explanation for the observed semiannual variation in Es layer occurrence and intensity, particularly in the Northern Hemisphere. Spectral analysis of Es layer data reveals that the dominant variations are associated with the annual oscillation, followed by the semiannual oscillation, underscoring the significant role of large-scale atmospheric oscillations in driving Es layer variability.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537196","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":"Global Structure of the Cislunar Magnetotail and Its Evolution During Substorms","authors":"M. I. Sitnov,&nbsp;G. K. Stephens,&nbsp;A. V. Artemyev,&nbsp;T. Motoba,&nbsp;N. A. Tsyganenko","doi":"10.1029/2025JA034018","DOIUrl":"https://doi.org/10.1029/2025JA034018","url":null,"abstract":"&lt;p&gt;So far, the structure and dynamics of the terrestrial magnetotail have largely been investigated within &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;31&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $31{R}_{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${R}_{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; is the Earth's radius) because of the lack of in-situ observations beyond that distance, as well as limitations of earlier empirical models. Here we reconstruct the global structure of the cislunar tail within &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;65&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $65{R}_{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; using 2011–2023 data from the ARTEMIS mission, the 2010 THEMIS-ARTEMIS transition orbits and other missions, such as IMP-8 and Geotail. The reconstruction is made using a new-generation data mining-based empirical algorithm with minimal ad hoc assumptions on the structure of the equatorial current sheet and its evolution during storms and substorms. It is found that the cislunar tail has a regular structure, stable in the substorm growth phase and regularly changing during the expansion and recovery phases. Substorms likely involve the formation of an X-line around &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;40&lt;/mn&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $40{R}_{E}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and magnetic flux accumulation earthward of it, which persists in the growth phase and flattens out after the substorm onset. Consistent with earlier reconstructions of the shorter tail region, the present ones reveal the near-Earth dipolarization of the magnetic field earthward of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∼&lt;/mo&gt;\u0000 &lt;mn&gt;17&lt;/mn&gt;\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537068","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":"Observational Evidence for the Nonlinear Growth of Chorus Waves Caused by Substorm Injected Energetic Electrons","authors":"Rui Chen,&nbsp;Yoshizumi Miyoshi,&nbsp;Hong Zhao,&nbsp;Huayue Chen,&nbsp;Xueyi Wang,&nbsp;Yoshiya Kasahara,&nbsp;Shoya Matsuda,&nbsp;Tomoaki Hori,&nbsp;Fuminori Tsuchiya,&nbsp;Atsushi Kumamoto,&nbsp;Atsuki Shinbori,&nbsp;Satoshi Kasahara,&nbsp;Shoichiro Yokota,&nbsp;Kunihiro Keika,&nbsp;Takefumi Mitani,&nbsp;Takeshi Takashima,&nbsp;Ayako Matsuoka,&nbsp;Mariko Teramoto,&nbsp;Kazuhiro Yamamoto,&nbsp;Iku Shinohara","doi":"10.1029/2025JA033931","DOIUrl":"https://doi.org/10.1029/2025JA033931","url":null,"abstract":"<p>Substorm energetic electron injections serve as a significant energy source for chorus wave generation, markedly altering the distribution of energetic electrons. Using the Arase satellite data, we present direct evidence for the nonlinear evolution of chorus waves following a substorm injection. The substorm injection causes the enhancement of energetic electron fluxes (∼20–200 keV) during which chorus waves appear as clear and intense rising-tone elements. Linear theoretical analysis shows that anisotropic energetic electrons provide free energy for the generation of seed chorus waves and the enhancement of energetic electrons increases the linear growth rate. Furthermore, nonlinear theoretical analysis shows that the increase in energetic electrons reduces the threshold amplitude, which is conducive to the chorus wave entering the nonlinear growth stage. These results indicate that nonlinear growth plays a significant role in the amplification and spectral evolution of chorus waves through a decrease in the threshold amplitudes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537093","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":"Penetration of Plasmapause Surface Waves Into the Plasmaspheric Plume","authors":"Yi-Jia Zhou,&nbsp;Fei He,&nbsp;Quan-Qi Shi,&nbsp;Jian Liu,&nbsp;Xiaoxin Zhang,&nbsp;Shuai Zhang,&nbsp;A. W. Degeling,&nbsp;Bo Li,&nbsp;Yong-Liang Zhang,&nbsp;Wen-Long Liu,&nbsp;An-Min Tian,&nbsp;Shi-Chen Bai,&nbsp;Zhi-Gang Yuan,&nbsp;Bin-Bin Ni,&nbsp;Zhong-Hua Yao,&nbsp;Rui-Long Guo,&nbsp;Qing-He Zhang,&nbsp;Yong Wei,&nbsp;Zong QiuGang","doi":"10.1029/2024JA033690","DOIUrl":"https://doi.org/10.1029/2024JA033690","url":null,"abstract":"<p>Plasmapause surface waves (PSWs) and plasmaspheric plumes are two crucial phenomena of magnetosphere-ionosphere coupling system in response to geomagnetic disturbances. However, it remains elusive what the potential interaction exists between them. In this letter, we identify the penetration of PSWs into the plasmaspheric plume and their interaction with each other. After the PSWs penetrating into the plume structure, they can oscillate the plume and cause the periodical scattering and precipitation of thermal particles. Meanwhile, the foundational frequency of PSWs in the plume becomes lower, and the higher-harmonic frequencies of PSWs are simultaneously observed. Their corresponding energy of modulated and precipitating particles also reduces to &lt;210 eV, which is different from the &lt;1 keV electrons and &lt;50 keV ions in those ordinary PSWs occurring near the main plasmapause. Our results advance our understanding of the complex interplay effect among various dynamic structures in the dusk inner-magnetosphere and aurora region.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524666","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":"Simulation of Acoustic-Gravity Waves Generated by an Earthquake and Explanation of the Ionospheric Disturbance Observed During 2023 M 7.7 Turkey Earthquake","authors":"Ting Li,&nbsp;Yongxin Gao,&nbsp;Chieh-Hung Chen,&nbsp;Yang-Yi Sun,&nbsp;Xuemin Zhang,&nbsp;Jaroslav Chum,&nbsp;Guanqun Zhou,&nbsp;Jian Wen,&nbsp;Xiaofei Chen","doi":"10.1029/2025JA033711","DOIUrl":"https://doi.org/10.1029/2025JA033711","url":null,"abstract":"<p>We present a semi-analytic method that allows efficiently simulating acoustic-gravity waves (AGWs) excited by an earthquake source in a stratified lithosphere-atmosphere model. First, we introduce the surface harmonic vectors to transform the atmospheric governing equations and the elastodynamic equations from the frequency-space to frequency-wavenumber domain. Next, we compute the wavefields in the frequency-wavenumber domain using a global matrix method incorporating boundary conditions and the source contribution. Finally, we obtain the time-space responses through the wavenumber integration and fast Fourier transform. We use this method to investigate the characteristics of AGWs generated by an earthquake source. The results reveal two main types of AGWs: the epicenter AGW generated by seismic waves near the epicenter and the head AGWs generated by the seismic waves that travel along the free surface. The epicenter AGW shows lower frequency compared with the head waves. AGWs caused by earthquakes with different focal mechanisms exhibit different energy distributions. Particularly, both the epicenter and head AGWs caused by a vertical strike fault are weak along the strike direction. The epicenter AGW is very sensitive to the source depth comparing to the head AGW. We also find that the Earth structure has little effect on the epicenter AGW but a significant effect on the head AGWs. We use our method to simulate the ionospheric disturbance observed from the Doppler frequency shift data following the 2023 Turkey M 7.7 earthquake. The good agreement suggests that our method provides a good understanding of the lithospheric and atmospheric coupling.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524493","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":"Imprints of Intense Geomagnetic Storm on Very Low Frequency (VLF) Radio Waves Over the Mediterranean Region","authors":"Muyiwa P. Ajakaiye,&nbsp;Ben Romano,&nbsp;Yuval Reuveni","doi":"10.1029/2025JA033796","DOIUrl":"https://doi.org/10.1029/2025JA033796","url":null,"abstract":"<p>The study of solar and geomagnetic activity effects on the D-region ionosphere (60–90 km altitude) using signals from very low frequency and low frequency (VLF, 3–30 kHz) transmitters has garnered considerable attention over the past decades. This research investigates the impacts of the geomagnetic storm (GMS) of 23–24 March 2023, utilizing VLF measurements from a monitoring station in the Mediterranean region. A variety of analytical approaches, including the traditional wavelet analysis for detecting events such as traveling ionospheric disturbances (TIDs) and or gravity waves (GWs), and the novel cross-wavelet coherence (WTC) correlation from cross wavelet transform methods, were employed to identify both apparent and subtle effects of the storm on the D-region ionosphere. Key findings include signal enhancement and attenuation of up to several tens of decibels during different phases of the storm's progression, observation of wave-like signatures (WLS) with time scales in the periods of GWs. The study also highlights significant delays in the D-region's response to magnetosphere-ionosphere energy exchanges driven by solar wind-magnetic reconnection during the storm. These delays, ranging from minutes to tens of minutes, were found to vary depending on the analytical technique used. The WTC analysis demonstrated maximum correlation values between amplitude deviations and the SYM-H geomagnetic index, ranging from ±0.9084 to ±0.9364 on the N/S signal channel and ±0.9188 to ±0.9363 on the E/W channel. These results not only corroborate previous research but also offer new insights into the dynamics of the D-region ionosphere during geomagnetic disturbances.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033796","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524665","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":"Orthogonal Electrodynamics in Multipole Magnetic Fields","authors":"R. A. Stoneback,&nbsp;C.-P. Lien,&nbsp;C.-T. Hsu,&nbsp;T. Matsuo","doi":"10.1029/2025JA033911","DOIUrl":"https://doi.org/10.1029/2025JA033911","url":null,"abstract":"<p>Electrodynamics investigations of plasma-neutral interactions require basis vectors that bridge geographic and geomagnetic coordinates. We present the first orthogonal basis vectors and coordinates for multipole magnetic fields that facilitates mapping geophysical parameters along magnetic field-lines. The calculated zonal, field-aligned, and meridional directions physically organize electric fields and plasma motions in a locally orthogonal manner. The basis is optimized for electrodynamics as the meridional and zonal vectors are vertical and horizontal at the magnetic equator. To counter assumptions from previous solutions, we demonstrate that multipole magnetic fields intrinsically support orthogonal basis vectors. The new basis also satisfies the conservation of magnetic flux and yields a magnetic field with zero divergence. Comparison of two different basis derivations demonstrates low basis uncertainty. The mapping functionality is validated through analytical example and comparison to a novel electrostatic field-line model. Using the orthogonal basis vectors a new orthogonal magnetic coordinate system is created. The equations for electrodynamics are expressed and simplified by the new coordinates, including a novel two-dimensional variant. Using the orthogonal basis we create an optimal meridional-zonal grid plane for numerically solving electrodynamics equations. To support geophysical interpretation, the meridional-zonal grid is tested by calculating a global electrostatic potential and electric field distribution. The validated basis is compared to non-orthogonal solutions and models to demonstrate that previous solutions are geophysically inconsistent. While previous solutions only worked for dipole fields, the new basis supports multipole fields, enabling electrodynamics investigations and models that were previously impossible.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033911","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519995","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":"Estimating Solar Wind Charge Exchange Generated Soft X-Rays in the Jovian Magnetosheath","authors":"Fenn Leppard,&nbsp;Atlas Patrick,&nbsp;Licia Ray,&nbsp;William R. Dunn,&nbsp;H. Todd Smith,&nbsp;Zhonghua Yao,&nbsp;Binzheng Zhang,&nbsp;TianRan Sun,&nbsp;Chi Wang","doi":"10.1029/2024JA033415","DOIUrl":"https://doi.org/10.1029/2024JA033415","url":null,"abstract":"<p>Solar Wind Charge eXchange (SWCX) generated soft x-rays are used extensively to study the interfaces between charged and neutral particles throughout the solar system. This paper outlines the development of a model of Jupiter's magnetosheath using magnetohydrodynamic derived boundary equations and a combination of in situ Juno measurements and numerical models for neutral and charged particle distributions. These are then used to model SWCX emissions in the Jovian magnetosheath for the OVII triplet to determine if the magnetosheath could be imaged in a similar fashion to the planned SMILE mission at Earth. We determine that whole detector counts per minute range from <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>5</mn>\u0000 <mo>±</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{-5pm 1}$</annotation>\u0000 </semantics></math> to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>3</mn>\u0000 <mo>±</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{-3pm 1}$</annotation>\u0000 </semantics></math> for various spacecraft, which are 4–5 orders of magnitude weaker than the diffuse soft x-ray background and, as such, argue that it is infeasible to study the x-ray emissions from the Jovian magnetosheath. Magnetosheath SWCX emissions would contribute a negligible amount to the diffuse background when performing higher signal x-ray observations at Jupiter such as x-ray aurora, emissions from the Io plasma torus, and fluorescence emissions from the Jovian moons in an in-situ setting, indicating that an x-ray instrument would be capable of performing observations of these brighter x-ray targets either inside or outside of the magnetopause.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033415","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514616","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":"Solar Wind-Magnetosphere Coupling Under Interim Steady Conditions","authors":"A. Brenner,&nbsp;T. I. Pulkkinen,&nbsp;M. W. Liemohn","doi":"10.1029/2025JA033771","DOIUrl":"https://doi.org/10.1029/2025JA033771","url":null,"abstract":"<p>Solar wind—magnetosphere coupling is an important driver of dynamics within the magnetosphere–ionosphere–thermosphere system, traditionally modeled using coupling functions. Most coupling functions assume the interaction is one-directional, that the solar wind conditions determine the energy that is transferred into the magnetosphere. To test this one-directional hypothesis, we use the Space Weather Modeling Framework to simulate nine 48-hr periods of idealized steady solar wind driving. The IMF inputs were varied every 2 hr, while the plasma conditions were held fixed for each of the nine intervals lasting 48 hr each. We calculate the energy flux through the magnetopause surface, including magnetopause motion effects. The energy transport through the open magnetopause is compared with two empirical coupling functions across all 2-hr intervals of steady solar wind driving. We find the energy input to the magnetosphere does not remain steady, as quantified by total variation, which has a median value of 1.36 TW. The variability results were binned according to a substorm indicator that combines signatures of dipolarization, plasmoid release, and substorm current wedge. Binning into substorm and non-substorm categories yielded different median variability values, but the substorm indicator failed to explain conditions of high variability in energy transport. Evaluation of energy injection results across all conditions suggests there may be a minimum energy state for a given solar wind condition. If such a minimum exists and can be reproduced, it may provide a basis for a new two-way solar wind–magnetosphere coupling function, including the effect of the state of the magnetosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA033771","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514617","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":"Evaluating Nudging Techniques in Implementing the Lower Atmosphere Variability Induced by Tides and Gravity Waves Into the TIEGCM","authors":"Xian Lu,&nbsp;Haonan Wu","doi":"10.1029/2024JA033517","DOIUrl":"https://doi.org/10.1029/2024JA033517","url":null,"abstract":"<p>We implement a nudging module into the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) to identify effective techniques for incorporating global-scale tides and medium-scale gravity waves (GWs) that induce ionospheric variability. Nudging the full fields of basic state variables minimizes contamination from spectral aliasing and mode coupling, ensuring the most accurate reproduction of each tidal component. In contrast, nudging solely diurnal tides has substantial spectral leakage into semidiurnal tides, leading to underestimations of their own amplitudes and day-to-day variabilities (DTDVs). Nudging both diurnal and semidiurnal tides mitigates such underestimations, establishing a minimal requirement for reproducing tidal dynamics and ionospheric DTDVs. Lower boundary forcing (LBF) causes significant deviations of tidal amplitudes and DTDVs near the boundary, but only a ∼10% underestimation above it. The DTDV of vertical ion drift gradually increases with more wave components incorporated and shows a ∼10% underestimation with LBF. Constraining geopotential height (<i>Z</i>*) is critical in TIEGCM to properly add GWs at lower levels. Model runs with <i>Z</i>* constrained exhibit reduced sensitivity to nudging levels: one-level nudging and LBF runs show 20%–30% underestimations of TID magnitudes compared to a four-scale-height nudging run. Conversely, when <i>Z</i>* is unavailable and only <i>U</i>, <i>V</i>, <i>T</i> are constrained, one-level nudging and LBF lead to 80%–90% underestimations of TIDs, with LBF entirely missing wave features. Therefore, multi-level nudging, especially with <i>Z</i>* unconstrained, is recommended to incorporate GWs. Overall, nudging provides a powerful tool to realistically incorporate observed or simulated waves across medium to global scales into ionosphere-thermosphere models, offering a data-driven perspective of variability for lower boundary conditions.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033517","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514639","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}