Journal of Geophysical Research: Space Physics最新文献

{"title":"Research on the Impact of Differences in Solar Flare Backgrounds of the Same-Class on Low-Frequency Time Code Time Service Signal","authors":"Zhen Qi,&nbsp;Luxi Huang,&nbsp;Xin Wang,&nbsp;Fan Zhao,&nbsp;Langlang Cheng,&nbsp;Qiang Liu,&nbsp;Yingming Chen,&nbsp;Xiaoqian Ren,&nbsp;Yuping Gao,&nbsp;Ping Feng","doi":"10.1029/2025JA033801","DOIUrl":"https://doi.org/10.1029/2025JA033801","url":null,"abstract":"<p>This study systematically investigates the impact of solar flares on the strength and timing deviation of China's low-frequency time code (BPC) time service signals under different occurrence background conditions based on same-class M1.1-class solar flare event. Seven representative observation cases were selected for the study, with calm day data 2–4 days before and after the cases used for comparison. The duration of solar flares and whether they were accompanied by geomagnetic storms were studied as variables. The study also conducted an in-depth analysis of the changes in BPC during solar flare occurrences using the SYM-H index, Kp index, SuperMAG geomagnetic data, and X-ray flux records from the GOES-16 satellite. The results show that when the X-ray flux reaches its peak, the BPC signals exhibit a sharp decay in strength and fluctuations in timing deviation. The longer the duration of the flare, the greater the disturbance to the signal. In the daytime mid-period, the response of BPC signals in the mid-to-low latitudes to geomagnetic storm background is not significant, as the dominant effect of solar radiation on exciting the D layer of the ionosphere masks the influence of geomagnetic disturbances. This study not only reveals the impact of background differences of same-class solar flares on BPC time service signals and provides strong support for the current understanding of signal-atmosphere interactions but also offers a theoretical basis for the anti-interference design of BPC systems.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224103","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":"Characteristics of Intraseasonal Oscillations During the 2016/2017 Boreal Winter at Mid-Latitudes and Their Relationship With Tropical Convective Activity","authors":"Lingnan Chen,&nbsp;Shaodong Zhang,&nbsp;Kaiming Huang,&nbsp;Chunming Huang,&nbsp;Yun Gong,&nbsp;Zheng Ma","doi":"10.1029/2024JA033665","DOIUrl":"https://doi.org/10.1029/2024JA033665","url":null,"abstract":"<p>Studies of Intraseasonal oscillations (ISOs) in the middle and upper atmosphere at mid- and high latitudes are limited compared to the extensive studies in the tropics. This study reports 20–25-day and 32–44-day oscillations in the zonal wind during the 2016/2017 boreal winter using meteor radar and mesosphere-stratosphere-troposphere (MST) radar observations over Beijing and Wuhan, supplemented by Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalysis data. Both ISOs are observed in the troposphere, stratosphere, and mesosphere, with stronger signals over Beijing than Wuhan; these oscillations have greater amplitudes in the middle and upper atmosphere at mid- and high latitudes, originating in the tropical lower atmosphere and propagating upward over the subtropical regions and poleward in the stratosphere and lower mesosphere. The 20–25-day oscillation possesses a zonal structure of westward wavenumber 1, while the 32–44-day oscillation comprises eastward and westward wavenumber 1 components. Both ISOs modulate the diurnal tide (DT), semidiurnal tide (SDT), and quasi-16-day wave (Q16DW), with the 32–44-day oscillation exhibiting a more pronounced effect. These waves are believed to be involved in the ISO activities during the observational interval. Crucially, strong correlations are found between these ISOs at mid-latitudes and tropical convective activities, evident in Outgoing Longwave Radiation and Sea Surface Temperature (SST) anomalies. Our study highlights the significant role of ISOs in coupling the ocean and atmosphere, the lower and middle/upper atmosphere, and the atmosphere at low and mid-latitudes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224102","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":"Combined Full Wave and Test Particle Simulations of the Io Footprint in the Jovian Aurora","authors":"W. W. Eshetu,&nbsp;R. L. Lysak,&nbsp;A. H. Sulaiman,&nbsp;S. S. Elliott","doi":"10.1029/2025JA034095","DOIUrl":"https://doi.org/10.1029/2025JA034095","url":null,"abstract":"<p>It is known that the perturbation of the co-rotating plasma of Jupiter by Io propagates as Alfvén waves along the magnetic field lines. These waves accelerate electrons, which leads to precipitation and the formation of an auroral footprint on the ionosphere. The Io footprint (IFP) has been observed in Infrared and ultraviolet emissions and known to have a complex morphology. Recently, Lysak et al. (2023, https://doi.org/10.1029/2022ja031180) modeled the propagation of the Alfvén waves in the Io-Jupiter system. This work will present test particle simulations based on these numerical models. By calculating the precipitating electron fluxes integrated with energy and solid angle in the ionosphere, and using it as a proxy for auroral emissions, we successfully reproduced many intricate features of the IFP. In particular, we replicate the main spot, leading spot, sub-dots, asymmetry between northern and southern ionosphere, and asymmetrically bifurcated tail. However, our simulations did not reproduce the stationarity of the sub-dots in the co-rotating frame, as observed by Moirano et al. (2021, https://doi.org/10.1029/2021ja029450). Additionally, we calculated the precipitating electron flux as functions of energy and pitch angle on the main spot, which could serve as input for models that calculate emissions from precipitating electron flux.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034095","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224383","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":"Bridging in Situ Satellite Measurements and Simulations of Magnetic Reconnection Using Recurrent Neural Networks","authors":"Cara L. Waters,&nbsp;Jonathan P. Eastwood,&nbsp;Naïs Fargette,&nbsp;David L. Newman,&nbsp;Martin V. Goldman,&nbsp;Martin O. Archer,&nbsp;Harry C. Lewis,&nbsp;Harley M. Kelly","doi":"10.1029/2025JA034383","DOIUrl":"https://doi.org/10.1029/2025JA034383","url":null,"abstract":"<p>Magnetic reconnection is inherently structured, with distinct spatial regions such as inflows, outflows, and separatrices playing key roles in energy conversion and particle transport. While in situ spacecraft measurements provide detailed local information, determining where a spacecraft lies within the global reconnection geometry remains a major challenge. Proxy-based methods are often ambiguous, while full reconstructions require strong assumptions and are difficult to apply systematically across events. Here, we present a method that bridges these approaches by using machine learning to infer global structural context from local measurements. We first apply <i>k</i>-means clustering to a 2.5-D particle-in-cell simulation to identify six characteristic symmetric reconnection regions. A recurrent neural network (RNN) is then trained on spacecraft-like trajectories through the simulation to classify time series data into these regions. When applied to Magnetospheric Multiscale (MMS) observations of magnetotail reconnection, this method successfully identifies regional transitions, including inflow, outflow, and separatrix crossings, in agreement with previous reconstructions where available. The approach provides a practical, scalable, and automated framework for determining spatial context in reconnection events without requiring full geometric reconstruction, enabling large-scale and efficient statistical studies of reconnection dynamics across multiple events.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JA034383","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224385","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":"Modeling Regional Electric Field Using EISCAT3D Observations","authors":"Habtamu W. Tesfaw,&nbsp;Heikki Vanhamäki,&nbsp;Ilkka Virtanen,&nbsp;Spencer Hatch,&nbsp;Matt Zettergren,&nbsp;Karl Laundal","doi":"10.1029/2024JA033625","DOIUrl":"https://doi.org/10.1029/2024JA033625","url":null,"abstract":"<p>EISCAT3D, which is in its final stage of construction, will be the next generation incoherent scatter radar (ISR) system to provide the full ion velocity vector across hundreds of kms in vertical and horizontal directions. This presents a tremendous opportunity to study the three-dimensional nature of ionospheric electrodynamics. Here we present a data-driven regional model of the electric field based on the EISCAT3D plasma velocity measurements. The measured F-region ion velocity data are fitted to a regional electric potential produced by a grid of spherical elementary systems. The performance of the model is demonstrated using simulated ionospheric parameters obtained from the GEMINI model. To simulate realistic radar measurement of the ion velocity, error estimates obtained from the <i>e3doubt</i> package are added to the ground-truth GEMINI data. Our model can be used with either multistatic or monostatic measurements of the ion velocity, and it can also integrate ion velocity data from other platforms, such as satellite sensors, into existing ISR measurements. The model captures the ground truth electric field including its complex spatial structure with average percentile differences of about 7%. Most accurate results are achieved with the multistatic data, but the general spatial structure of the electric field can be captured also with monostatic data, if optimal beam patterns and regularization are used. The modeling method is also applied using real monostatic line-of-sight ion velocity data measured by the Poker Flat ISR. The modeled electric field shows reasonably well-behaved variations in latitude and longitude within the radar's field of view.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 10","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033625","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224410","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":"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}