Journal of Geophysical Research: Space Physics最新文献

{"title":"An Efficient Positivity-Preserving Finite Difference Scheme for Solving the Fokker-Planck Diffusion Equation","authors":"Chengjie Qi,&nbsp;Zhenpeng Su,&nbsp;Zhiyong Wu,&nbsp;Huinan Zheng,&nbsp;Yuming Wang","doi":"10.1029/2024JA033584","DOIUrl":"https://doi.org/10.1029/2024JA033584","url":null,"abstract":"<p>The Fokker-Planck diffusion equation is widely used for simulating the evolution of Earth's radiation belt electrons, which pose significant hazards to space-borne systems. To preserve the positivity of the numerical solution of the electron phase space density (PSD), several finely designed finite difference, Monte Carlo, spatiotemporal interpolation, and finite volume schemes have been developed. However, these schemes often suffer from either high implementation complexity or low execution efficiency. Here we propose an efficient, easy-to-implement, and positivity-preserving finite difference scheme, named the Semi-Implicit Logarithmic Linearization (SILL) scheme. The basic principle is to linearize the nonlinear equation of the natural logarithmic PSD. This scheme ensures accuracy and stability, even with large time steps, up to hundreds of seconds for typical radiation belt electron diffusion processes. Nonetheless, it exhibits oversensitivity to near-vanishing phase space densities, which necessitates reduced time steps when handling extremely large variations in orders of magnitude between neighboring grid points. We have publicly released the protype code of the SILL scheme, which could be useful for the radiation belt modeling community.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824721","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":"Parametric Study of Asymmetric Propagation of Guided and Unguided EMIC Waves Near the Local Characteristic Frequencies","authors":"Xiang Xu,&nbsp;Chen Zhou","doi":"10.1029/2024JA033505","DOIUrl":"https://doi.org/10.1029/2024JA033505","url":null,"abstract":"&lt;p&gt;Previous studies demonstrate that the propagation of the guided and unguided electromagnetic ion cyclotron (EMIC) waves near the local characteristic frequencies in a dipole field shows prominent asymmetry with the wave vector &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;k&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $mathbf{k}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; pointing toward lower L shells (wave normal angle &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;ψ&lt;/mi&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mo&gt;∘&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $psi &lt; {0}^{circ }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and higher L shells (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;ψ&lt;/mi&gt;\u0000 &lt;mo&gt;&gt;&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mo&gt;∘&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $psi &gt; {0}^{circ }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) at low magnetic latitudes (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;20&lt;/mn&gt;\u0000 &lt;mo&gt;∘&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${theta }_{M}&lt; {20}^{circ }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) using representative cases. The &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;ψ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $psi $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mi&gt;M&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${theta }_{M}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; dependence of this asymmetric behavior and the role of magnetic gradients in this process are not clear. Using full-wave simulations and ray theories, a parametric study is conducted to address these questions. We find that the refraction due to the magnetic gradient term can be quantified by &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mi&gt;Ψ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${Delta }{Psi }$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (the variation of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;ψ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $psi $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; during the ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822282","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 Counter Electrojet Using Multi-Spacecraft Swarm Observations","authors":"J. Sreelakshmi,&nbsp;Geeta Vichare","doi":"10.1029/2024JA033485","DOIUrl":"https://doi.org/10.1029/2024JA033485","url":null,"abstract":"<p>The characteristics of the westward ionospheric current flowing at the geomagnetic equator, known as Counter Electrojet (CEJ), are studied here using multi-satellite Swarm mission magnetic field data collected during January 2014 to March 2021. For the first time, the simultaneous measurements from multiple satellites are used to investigate the various features of the CEJ, including its longitudinal extent. The CEJ events occur in ∼19.8% of quiet-time electrojet profiles during the period of study. The local time, seasonal, and longitudinal variations of the CEJ amplitude and occurrence percentage during geomagnetically quiet days confirm many of the earlier reported observations. It is found that the CEJ is more prone to occur during morning and less frequent at noon, while the amplitude of CEJ peaks during noon hours. Longitudinal pattern of CEJ occurrence shows distinct four-peaks at ∼50°E, ∼150°E, ∼230°E and ∼310°E longitudes. Also, CEJ occurrence peaks from June to August. The CEJ occurrence and meteorite ablation rates are found to be moderately correlated on a monthly scale, and no one-to-one correlation found in the Indian region. For the first time, the longitudinal extent of CEJ is estimated using simultaneous observations from Swarm <i>A</i> and <i>B</i>. It is found that the CEJ has predominant longitudinal extent of 15°–25°, although it can also have larger longitudinal coverage more than or up to 165°, under the assumption of temporal and spatial stability of CEJ.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822284","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":"Spacecraft Discharge Time Constants Determined From Electron-Flux Suppression During Sounding-Radar Operation at Mars","authors":"Sebastián Rojas Mata,&nbsp;Stas Barabash,&nbsp;Andrii Voshchepynets,&nbsp;Mats Holmström,&nbsp;Beatriz Sánchez-Cano,&nbsp;Mark Lester,&nbsp;Andrea Cicchetti,&nbsp;Roberto Orosei","doi":"10.1029/2024JA033608","DOIUrl":"https://doi.org/10.1029/2024JA033608","url":null,"abstract":"<p>Spacecraft discharge time constants are calculated from measurements of electron differential flux before and during operation of an ionospheric sounding radar. Determining these time constants provides insight into how the operation of a sounding radar affects the surrounding plasma's interaction with the spacecraft. The analysis is enabled by the fixed-frequency operation mode of a sounding radar which enhances resonant interaction with the ambient plasma. This mode's effect on measured energy spectra of ion and electron fluxes is described. Measurements of electron fluxes disturbed by radar operation serve as input to a model of spacecraft discharge for calculating capacitive discharge time constants. A case study using electron fluxes measured at Mars yields discharge time constants in the range 0.6–0.8 ms and reveals that a residual potential around <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>4</mn>\u0000 </mrow>\u0000 <annotation> ${-}4$</annotation>\u0000 </semantics></math> V remains on the spacecraft long after radar operation ceases. The minimum spacecraft potential cannot be determined with these data and model due to the narrow energy range of electrons in the ambient plasma.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033608","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822283","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":"The Wave Normal Angle Characteristic of Whistler-Mode Waves in the Dayside Terrestrial Space Based on MMS Observations","authors":"H. Zhang,&nbsp;J. Y. Lu,&nbsp;Z. H. Zhong,&nbsp;B. P. Feng,&nbsp;M. Wang,&nbsp;R. X. Tang,&nbsp;X. H. Deng","doi":"10.1029/2025JA033789","DOIUrl":"https://doi.org/10.1029/2025JA033789","url":null,"abstract":"&lt;p&gt;Wave normal angle (WNA) is an important parameter in the analysis of wave-particle interactions. The WNA distribution may significantly influence the effective interaction between the waves and solar wind electrons. As a region of direct interaction with the solar wind, the WNA distribution of whistler-mode waves in the dayside terrestrial space is still unclear. This paper reports statistical work on the WNA distribution of whistler-mode waves in the dayside terrestrial region. The results show that whistler-mode waves with quasi-parallel WNA &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;mn&gt;35&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $(theta &lt; 35{}^{circ})$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; tend to increase gradually near the magnetopause, while the occurrence rate of oblique waves &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;θ&lt;/mi&gt;\u0000 &lt;mo&gt;≥&lt;/mo&gt;\u0000 &lt;mn&gt;35&lt;/mn&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $(theta ge 35{}^{circ})$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; increases significantly in the magnetosheath with increasing solar wind dynamic pressure &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mi&gt;w&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({P}_{sw}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. Under the strong &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;P&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;s&lt;/mi&gt;\u0000 &lt;mi&gt;w&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${P}_{sw}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; condition, the distribution of WNAs both in quasi-parallel and oblique decreases sharply within the 0.5–0.8 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;c&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${f}_{ce}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; frequency range. Moreover, we find that stron","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809530","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":"Relationship Between Each FAC Component and Auroral Electron Precipitation During Substorms","authors":"B. H. Qu,&nbsp;J. Y. Lu,&nbsp;Z. W. Wang,&nbsp;J. J. Liu,&nbsp;M. Wang,&nbsp;J. Y. Li,&nbsp;H. Zhang","doi":"10.1029/2024JA033547","DOIUrl":"https://doi.org/10.1029/2024JA033547","url":null,"abstract":"<p>It is traditionally assumed that upward currents correspond to electron precipitation, suggesting that electron precipitation should align with Region 2 (R2) Field-Aligned Currents (FACs) in the dawn sector and Region 1 (R1) FACs in the dusk sector. However, some previous studies have indicated systematic discrepancies between the locations of auroral electron precipitation and R1/R2 FACs, a topic that remains controversial and lacks an adequate explanation. This study aims to investigate and explain these differences. We conducted a detailed analysis of the relationship between FACs and auroral electron precipitation throughout the substorm phases, including the growth, expansion, and recovery phases. It is shown that (a) the region of large energy flux in auroral electron precipitation corresponds to the transition zone between R1 and R2 FACs, (b) auroral electron precipitation enhances height-integrated conductances, which combine with downward vorticities to be associated with upward magnetospheric-origin FACs, and (c) auroral electron precipitation also strengthens the gradient of height-integrated conductances and this enhanced gradient, together with drift velocities, contributes to the formation of downward ionospheric-origin FACs. The interplay between downward ionospheric-origin FACs and upward magnetospheric-origin FACs shifts the transition zone to poleward, resulting in the observed correlation between the region of large energy flux and the transition zone. This is similar to the mechanism of feedback instability. Specifically, the height-integrated conductance gradients due to auroral electron precipitation drive polarized currents, fed by downward and upward FACs. These FACs shift the transition zone poleward and enhance auroral electron precipitation energy flux, forming a closed feedback loop.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809529","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":"Electron-Scale Energy Transfer Due To Lower Hybrid Waves During Asymmetric Reconnection","authors":"Sabrina F. Tigik,&nbsp;Daniel B. Graham,&nbsp;Yuri V. Khotyaintsev","doi":"10.1029/2024JA033503","DOIUrl":"https://doi.org/10.1029/2024JA033503","url":null,"abstract":"<p>We use Magnetospheric Multiscale mission data to investigate electron-scale energy transfer due to lower hybrid drift waves during magnetopause reconnection. We analyze waves observed in an electron-scale plasma mixing layer at the edge of the magnetospheric outflow. Using high-resolution <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>7.5</mn>\u0000 <mspace></mspace>\u0000 <mi>m</mi>\u0000 <mi>s</mi>\u0000 </mrow>\u0000 <annotation> $7.5hspace*{.5em}mathrm{m}mathrm{s}$</annotation>\u0000 </semantics></math> electron moments, we obtain an electron current density with a Nyquist frequency of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>66</mn>\u0000 <mspace></mspace>\u0000 <mi>H</mi>\u0000 <mi>z</mi>\u0000 </mrow>\u0000 <annotation> ${sim} 66hspace*{.5em}mathrm{H}mathrm{z}$</annotation>\u0000 </semantics></math>, sufficient to resolve most of the lower hybrid drift wave power observed in the event. We then employ wavelet analysis to evaluate <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>δ</mi>\u0000 <mi>J</mi>\u0000 <mspace></mspace>\u0000 <mo>⋅</mo>\u0000 <mspace></mspace>\u0000 <mi>δ</mi>\u0000 <mi>E</mi>\u0000 </mrow>\u0000 <annotation> $delta mathbf{J},cdot ,delta mathbf{E}$</annotation>\u0000 </semantics></math>, which accounts for the phase differences between the fluctuating quantities. The analysis shows that the energy exchange is localized within the plasma mixing layer, and it is highly fluctuating, with energy bouncing between waves and electrons throughout the analyzed time and frequency range. However, the cumulative sum over time indicates a net energy transfer from the waves to electrons. We observe an anomalous electron flow toward the magnetosphere, consistent with diffusion and electron mixing. These results indicate that waves and electrons interact dynamically to dissipate the excess internal energy accumulated by sharp density gradients. We conclude that the electron temperature profile within the plasma mixing layer is produced by a combination of electron diffusion across the layer, as well as heating by large-scale parallel potential and lower hybrid drift waves.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809531","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":"Temporal and Spatial Dynamics of Nitric Oxide Production at High Latitudes Caused by an ICME-Driven Storm onDec. 14, 2006","authors":"Kevin Delano,&nbsp;Eftyhia Zesta,&nbsp;Denny M. Oliveira,&nbsp;Miguel Martínez Ledesma,&nbsp;Shaylah Mutschler","doi":"10.1029/2024JA033406","DOIUrl":"https://doi.org/10.1029/2024JA033406","url":null,"abstract":"<p>Geomagnetic storms release large amounts of energy on Earth's upper atmosphere at high latitudes that result in the heating and upward expansion of the neutral gas. During geomagnetic storms driven by interplanetary coronal mass ejections (ICMEs), neutral mass density heating and cooling times are shorter for stronger storms and longer for weaker storms. The start time influx of energy into Earth's upper atmosphere allows for the enhanced production of nitric oxide (NO) at high latitudes, which in turn cools the thermosphere by radiating away excess energy. As a result, greater NO production results in quicker thermospheric cooling. While the production of NO on a global scale has been linked to the storm cycle, the spatiotemporal evolution of NO with respect to the storm onset and storm strength must also be understood to improve predictions of the storm evolution cycle and their impact on low-Earth orbit satellites. In this study, we investigate the effects of a particular ICME-driven storm on the production of NO at high latitudes and associated local time asymmetries. We compare NO measurements from the Thermosphere, Ionosphere, Mesosphere Dynamics (TIMED) spacecraft to neutral mass density measurements from the Challenging Minisatellite Payload spacecraft and find that the impact of the shock prior to the storm, in addition to the onset of the storm itself, is responsible for an increase in NO production. We also observe a dawn-dusk asymmetry in high-latitude NO production and identify solar wind geometry and internal processes as potential drivers for this asymmetry.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809596","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":"Ionospheric D Region: Characteristics Near Dawn and Dusk","authors":"Neil R. Thomson,&nbsp;Mark A. Clilverd,&nbsp;Craig J. Rodger","doi":"10.1029/2024JA033610","DOIUrl":"https://doi.org/10.1029/2024JA033610","url":null,"abstract":"<p>The characteristics of very low frequency (VLF) radio wave propagation in the Earth-ionosphere waveguide are determined particularly through dawn and dusk using phase and amplitude measurements of man-made signals propagating below the ionospheric <i>D</i> region. For the first time variations of “Wait” height and sharpness parameters, <i>H'</i> and <i>β,</i> have been determined for dawn and dusk conditions. These measurements provide observational data to constrain <i>D</i> region modeling efforts, extending the capabilities of VLF propagation monitoring for geophysical phenomena such as lightning, solar flares, and energetic particle precipitation. At mid-latitudes, <i>H'</i> varied from ∼85 km at night, then, starting from solar zenith angle (SZA) ∼ −97.5°, rapidly down to ∼73 km at dawn (SZA = −90°), then back up to ∼78 km at SZA ∼ −75° and then down to the appropriate noon value for the latitude (and season). In contrast, from noon through dusk to night, <i>H'</i> varied essentially monotonically from ∼70 to 75 km through ∼80 to ∼85 km. At low latitudes no dawn minimum in <i>H'</i> was observed, due to the reduced effect of galactic cosmic rays (GCR). Sharpness, <i>β</i>, varied from its nighttime value of ∼0.6 km⁻¹ down to a minimum of ∼0.25 km⁻¹ at SZA ∼85° near dusk or ∼75° near dawn, rising again to (SZA-dependent) noon values of ∼0.35–0.5 km⁻¹. The results are interpreted through the geophysical effects controlling <i>D</i> region electrons, including the daytime dominant role of solar Lyman-α from low to mid-latitudes, and the greater role of GCR at increasingly higher mid-latitudes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033610","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Solar Proton Events on the Stratospheric Polar Vortex in the Northern Hemisphere: A Quantitative Analysis","authors":"Hui Li,&nbsp;Yaxuan Li,&nbsp;Yuting Wang,&nbsp;Jingkang Sun,&nbsp;Chi Wang","doi":"10.1029/2024JA033068","DOIUrl":"https://doi.org/10.1029/2024JA033068","url":null,"abstract":"<p>The stratospheric polar vortex (SPV) profoundly affects northern hemisphere weather and climate, with its dynamics influenced by terrestrial and solar factors. Despite established terrestrial influences, the quantitative effects of solar energetic particles have not yet been fully understood. This study presents a quantitative analysis of 27 intense solar proton events (SPEs) from 1986 to 2020, revealing a significant correlation between the integrated flux of SPEs and enhanced SPV wind speeds across altitudes. Notably, the wind speed enhancements, ranging from 1.8 m/s (15.1%) at 100 hPa to 3.0 m/s (7.3%) at 1 hPa, demonstrate an altitude-dependent pattern, with the greatest impacts of 5.8 m/s (19.1%) at 5 hPa. A partial correlation analysis identifies SPEs as the dominant driver of SPV enhancement in the middle and lower stratosphere, while ultraviolet radiation dominates at the stratopause. We propose a mechanism involving the amplification of the meridional temperature gradient due to differential ozone responses, thereby linking solar activity to the modulation of the SPV. These findings enhance our understanding of solar-terrestrial interactions and their implications for climate modeling.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 4","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809595","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}