Journal of Geophysical Research: Space Physics最新文献

{"title":"Juno Observations of Jupiter's Magnetodisk Plasma: Implications for Equilibrium and Dynamics","authors":"Z.-Y. Liu, M. Blanc, N. Andre, F. Bagenal, R. J. Wilson, F. Allegrini, M. Devinat, B. Mauk, J. E. P. Connerney, S. Bolton","doi":"10.1029/2024JA032976","DOIUrl":"https://doi.org/10.1029/2024JA032976","url":null,"abstract":"<p>The Jovian magnetodisk plays an essential role in the dynamics of the Jupiter system by coupling its various components. Here, we investigate the Juno (JADE, JEDI, and MAG) observations of the magnetodisk within 20–80 Jupiter radii (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>R</mi>\u0000 <mi>J</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{R}}_{J}$</annotation>\u0000 </semantics></math>) in the 0–6 hr local time sector. JADE and JEDI data are combined to generate equatorial plane distributions of density, pressure, temperature, and anisotropy of electrons, protons, and heavy ions. Results show: (a) Heavy ions dominate both the number density and pressure. (b) The number density and pressure of all species decrease with radial distance. (c) The temperature increases for electrons and heavy ions and decreases for protons as radial distance increases. (d) On average, the parallel pressure exceeds the perpendicular pressure for all species. Based on these distributions, we explore the equilibrium and dynamics of the magnetodisk and show that: (a) Radial force balance is primarily achieved between the inward magnetic stress and the outward plasma anisotropy force. (b) An examination of the kappa parameters indicates that electrons, protons, and heavy ions primarily undergo adiabatic motion, magnetic moment diffusion, and stochastic motion, respectively. (c) A radial diffusion coefficient is derived from the radial profile of mass, providing an estimate of the timescale for radial transport from 20 to 80 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>R</mi>\u0000 <mi>J</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{R}}_{J}$</annotation>\u0000 </semantics></math> of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math> 7 hr (d) The total mass (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>5.0</mn>\u0000 <mo>×</mo>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>7</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $5.0times 1{0}^{7}$</annotation>\u0000 </semantics></math> kg) and thermal energy (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>3.8</mn>\u0000 <mo>×</mo>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>37</mn>\u0000 </ms","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032976","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142708082","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":"GOES-R Series X-Ray Sensor (XRS): 1. Design and Pre-Flight Calibration","authors":"Thomas N. Woods,&nbsp;Thomas Eden,&nbsp;Francis G. Eparvier,&nbsp;Andrew R. Jones,&nbsp;Donald L. Woodraska,&nbsp;Phillip C. Chamberlin,&nbsp;Janet L. Machol","doi":"10.1029/2024JA032925","DOIUrl":"https://doi.org/10.1029/2024JA032925","url":null,"abstract":"<p>The X-Ray Sensor (XRS) has been making full-disk observations of the solar soft X-ray irradiance onboard National Oceanic and Atmospheric Administration's (NOAA) Geostationary Operational Environmental Satellites since 1975. Critical information about solar activity for space weather operations is provided by XRS measurements, such as the classification of solar flare magnitude based on X-ray irradiance level. The GOES-R series of XRS sensors, with the first in the series launched in November 2016, has a completely different instrument design compared to its predecessors, GOES-1 through GOES-15. To provide continuity, the two GOES-R XRS spectral bands remain unchanged providing the solar X-ray irradiance in the 0.05–0.4 nm and 0.1–0.8 nm bands. The changes for the GOES-R XRS instrument included using Si photodiodes instead of ionization cells to improve performance, using multiple channels per X-ray band to allow for a wider dynamic range, and providing accurate radiometric calibrations using the National Institute of Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility in Gaithersburg, Maryland. In addition to the standard XRS data product of solar irradiances in the two X-ray bands, a new real-time flare location data product is also available from the GOES-R XRS instruments because two channels are quadrant photodiodes for position detection. The design and pre-flight calibration results for this next-generation XRS instrument are presented here in this XRS Paper-1, and in-flight solar X-ray measurements from GOES-16, GOES-17, and GOES-18 are provided in the XRS Paper-2.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032925","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685377","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 Excitation of Second Harmonic Poloidal ULF Waves Through Drift-Bounce Resonance With Protons in the Magnetic Dip","authors":"Yan Zhuang,&nbsp;Chao Yue,&nbsp;Li Li,&nbsp;Xu-Zhi Zhou,&nbsp;Qiu-Gang Zong,&nbsp;Shan Wang,&nbsp;Ying Liu,&nbsp;Xing-Yu Li,&nbsp;Ze-Fan Yin,&nbsp;Yong-Fu Wang,&nbsp;Zhi-Yang Liu,&nbsp;Haobo Fu","doi":"10.1029/2024JA032804","DOIUrl":"https://doi.org/10.1029/2024JA032804","url":null,"abstract":"<p>The drift-bounce resonance between ultralow-frequency (ULF) waves and charged particles is an efficient way to transfer energy. In this study, we report the excitation of ULF waves through drift-bounce resonance with protons in the magnetic dip for the first time. On 4 September 2015, Van Allen probe B observed ULF signals with a frequency of ∼10 mHz inside the magnetic dip during substorms at the dusk side. The ULF waves are further diagnosed as second harmonic poloidal waves. The 54–67 keV protons in the magnetic dip exhibit oscillations with the same period as ULF waves, providing evidence for drift-bounce resonance. Through finite Larmor radius effects, we determined that the ULF waves propagate eastward with an azimuthal wave number in the range of 237–277. The ULF waves are excited with free energy related to the enhanced proton phase space density in the magnetic dip.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685376","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":"First Meteor Radar Observations of Gravity Waves in the Mesosphere and Lower Thermosphere Over Yinchuan (38.8°N, 106.8°E), China","authors":"Shaodong Zhang,&nbsp;Yuting Guan,&nbsp;Yun Gong,&nbsp;Zheng Ma,&nbsp;Chunming Huang,&nbsp;Kaiming Huang,&nbsp;Jiahui Luo,&nbsp;Hualong Huang","doi":"10.1029/2024JA033006","DOIUrl":"https://doi.org/10.1029/2024JA033006","url":null,"abstract":"<p>By using the WHU-YC meteor radar observations (2019.11–2021.10) in Yinchuan (38.8°N, 106.8°E), we studied the winds, tides, and gravity waves (GWs) in the Mesosphere and Lower Thermosphere (MLT) over northwestern China for the first time. Distinct annual and semi-annual oscillations (AO and SAO) appeared in the background winds, showed maximum and minimum in summer (∼40 m/s) and spring (∼−14 m/s), respectively, and exhibited wind shear in summer and winter. Affected by the background winds, GW activity similarly exhibited AO, with maximum kinetic energy density (KED) in May (∼4.0 × 10⁻³ J/m³). KEDs consistently declined with altitude, indicating severe GW dissipation in the MLT. GW's momentum fluxes (MFs) are predominantly positive below ∼88 km and reverse negative above. MFs reached ∼10⁻⁴ J/m³ in summer and autumn, while weaker in winter and spring. The GW drag reached ∼443.8 m/s/d in zonal, closely correlated with the tendency, highlighting the substantial GW impact on the mean flow. The intense GW activities here approached some hot spots, possibly due to Yinchuan's characteristic topography, resulting in more terrain-excited GWs. Despite no discernible seasonal variation in GW's intermittency, the Gini coefficient steadily increased with altitude, implying GWs upward with smaller MF are easier to dissipate. The diurnal tide (DT) significantly modulated GWs at almost all heights. Despite comparable amplitudes of the semidiurnal tide (SDT) to DT, the weaker SDT modulation only concentrated in 84–86 km because of its longer vertical wavelength, emphasizing tides' vertical wavelengths are crucial parameters in GW's modulation.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691330","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":"Influence of Lower Atmospheric Variability: An Investigation of Delayed Ionospheric Response to Solar Activity","authors":"Rajesh Vaishnav,&nbsp;Christoph Jacobi,&nbsp;Erik Schmölter,&nbsp;Hanna Dühnen","doi":"10.1029/2024JA032999","DOIUrl":"https://doi.org/10.1029/2024JA032999","url":null,"abstract":"<p>This study aims to examine the impact of lower atmospheric forcing on upper atmospheric variability using the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). We conducted numerical experiments comparing induced variability due to Hough Mode Extension (HME) tides constrained by winds and temperatures from Ionospheric Connection Explorer-Michelson Interferometer for Global High-Resolution Thermospheric Imaging (ICON-MIGHTI) observations. Our model comparisons focus on the changes in the composition of the thermosphere-ionosphere and the delayed ionospheric response to the 27-day solar EUV flux variations during periods of low solar activity. We report the results of model simulations with and without tidal forcing at the approximate 97 km lower boundary of the TIEGCM. The differences led to changes in thermosphere-ionosphere parameters such as electron density, peak electron density, and the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mo>/</mo>\u0000 <msub>\u0000 <mi>N</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> $O/{N}_{2}$</annotation>\u0000 </semantics></math> ratio. The results show that the impact of tidal forcing is mainly observed in the low- and mid-latitude regions, affecting the correlation between <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mo>/</mo>\u0000 <msub>\u0000 <mi>N</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> $O/{N}_{2}$</annotation>\u0000 </semantics></math> and NmF2. This change in correlation affects the amount of ionospheric delay. When tidal forcing is included, the modeled delay improves compared to the observed delay during low solar activity. The spatial variation of ionospheric delay due to induced tidal effects highlights the importance of understanding lower atmospheric forcing in thermosphere-ionosphere models. This is crucial for predicting and understanding the ionospheric response to solar flux.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685239","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":"Direction Finding Studies of Simultaneous Auroral 2fce and 3fce Roar Cyclotron Harmonic Radio Emissions","authors":"T. M. Godfrey,&nbsp;J. LaBelle","doi":"10.1029/2024JA033162","DOIUrl":"https://doi.org/10.1029/2024JA033162","url":null,"abstract":"&lt;p&gt;Auroral roar originates in Earth's ionosphere at altitudes of several hundred kilometers where the upper hybrid frequency matches a harmonic of the electron gyrofrequency. These radio emissions are important for remote sensing of ionospheric plasma conditions and processes, and their physics is similar to that of astrophysical radio emissions. In this study, direction finding was used to establish the distribution of direction of arrival (DOA) angles for the third harmonic &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;3&lt;/mn&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;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left(3{f}_{ce}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; emissions and to compare the direction angles of second harmonic &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&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;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left(2{f}_{ce}right)$&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;mn&gt;3&lt;/mn&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; $3{f}_{ce}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; events when they occur simultaneously. Data were collected for 42 events from 9 May 2022 to 20 May 2023 by a three antenna array in Toolik Lake, AK (68.6°N, 149.6°W, 68.5° magnetic latitude) with a DOA distribution centered overhead. 30% of the events coming from the south, for which azimuth deviations due to refraction are less significant, were on the same azimuth within 10°, the uncertainty of the measurement. This is a lower bound on the fraction of simultaneous harmonic &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mn&gt;2&lt;/mn&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; $2{f}_{ce}$&lt;/annotation&gt;\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685252","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":"Modeling the Emission of Energetic Neutral Atoms in Titan's Dynamic Magnetospheric Environment","authors":"Tyler Tippens,&nbsp;Sven Simon,&nbsp;Elias Roussos","doi":"10.1029/2024JA033103","DOIUrl":"https://doi.org/10.1029/2024JA033103","url":null,"abstract":"<p>To provide context for Cassini observations of energetic neutral atoms (ENAs) generated by charge exchange between Titan's atmosphere and energetic magnetospheric ions, we compute synthetic ENA images for a variety of uniform and draped electromagnetic field configurations, flyby scenarios, and viewing geometries. Starting with the idealized case of the magnetospheric field near Titan pointing southward, we calculate the observable ENA emission morphology for a large set of detector locations, each mimicking the properties of Cassini's Ion and Neutral Camera. Regardless of whether the electromagnetic fields near Titan are treated as uniform or draped, ENA production occurs within a thin shell of radial thickness 85 km, located directly above the moon's exobase. The observable ENA morphology is largely controlled by the angle between the detector's boresight vector and Saturn's magnetospheric field. Both the radius and the sense of energetic ion gyration carve distinct gaps in the ENA emission pattern. Field line draping around Titan leaves a discernible imprint in the ENA emissions only for a narrow range of viewing geometries. We also apply the model to study the ENA images taken during the T20 and T24 flybys. During both encounters, the ambient magnetospheric field displayed frequent transitions between Saturn's northern and southern magnetodisk lobes. We show that the notion of a steady-state interaction between Titan and an averaged magnetospheric background field is not suitable to explain the observed ENA morphology. Instead, ambient field variations measured more than 1 hr before ENA image acquisition still leave an imprint in the emission pattern.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033103","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685368","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":"Equatorial Source of Oblique Electromagnetic Ion Cyclotron Waves: Peculiarities in the Ion Distribution Function","authors":"David S. Tonoian,&nbsp;Xiao-Jia Zhang,&nbsp;Anton Artemyev,&nbsp;Xin An","doi":"10.1029/2024JA032848","DOIUrl":"https://doi.org/10.1029/2024JA032848","url":null,"abstract":"<p>Electromagnetic ion cyclotron (EMIC) waves are important for Earth's inner magnetosphere as they can effectively drive relativistic electron losses to the atmosphere and energetic (ring current) ion scattering and isotropization. EMIC waves are generated by transversely anisotropic ion populations around the equatorial source region, and for typical magnetospheric conditions this almost always produces field-aligned waves. For many specific occasions, however, oblique EMIC waves are observed, and such obliquity has been commonly attributed to the wave off-equatorial propagation in curved dipole magnetic fields. In this study, we report that very oblique EMIC waves can be directly generated at the equatorial source region. Using THEMIS spacecraft observations at the dawn flank, we show that such oblique wave generation is possible in the presence of a field-aligned thermal ion population, likely of ionospheric origin, which can reduce Landau damping of oblique EMIC waves and cyclotron generation of field-aligned waves. This generation mechanism underlines the importance of magnetosphere-ionosphere coupling processes in controlling wave characteristics in the inner magnetosphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142692052","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":"Observations of Strong Range Spread F and Nighttime Ionospheric Enhancement in the Mid-Latitude Region Under Geomagnetically Quiet Conditions","authors":"Chunhua Jiang,&nbsp;Rong Tian,&nbsp;Tongxin Liu,&nbsp;Guobin Yang,&nbsp;Hua Shen,&nbsp;Wengeng Huang,&nbsp;Zhengyu Zhao","doi":"10.1029/2024JA033106","DOIUrl":"https://doi.org/10.1029/2024JA033106","url":null,"abstract":"<p>Spread F is one of most widely observed nighttime ionospheric irregularities by ionosondes in the equatorial, low- and mid-latitude regions. One type of spread F, known as strong range spread F (backscatter echoes beyond the critical frequency of the F2 layer, foF2), has been observed in the equatorial and low-latitude regions but not at middle latitudes. This study reported for the first-time observations of strong range spread F at Zhangye Station (ZHY, Geographical latitude 39.4°N, longitude 100.0°E, Dip Lat 29.6°N) on 29 November 2019 (under quiescent conditions). Observations show that strong range spread F occurred at first during midnight (∼16:30 UT), accompanied with mid-latitude nighttime ionospheric enhancements in foF2 and total electron content (TEC). Then, it becomes more pronounced when ionospheric collapse occurred. The measurements from satellite revealed that there are large opposite temperature and density gradients (temperature decreased sharply from ∼3100 to ∼2500 K, however, electron density increased sharply from ∼0.3 e5 to ∼1.2 e5 cm⁻³ around Zhangye Station) during this event. Results suggest that mid-latitude strong range spread F might be attributed to temperature gradient instabilities.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142692051","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":"Calculation and Evaluation of Neutral Winds in the Lower Thermosphere Based on SYISR Observations","authors":"Ning Zhang,&nbsp;Xinan Yue,&nbsp;Junyi Wang,&nbsp;Yihui Cai,&nbsp;Lianhuan Hu,&nbsp;You Yu,&nbsp;Xu Zhou,&nbsp;Feng Ding,&nbsp;Mingyuan Li,&nbsp;Baiqi Ning","doi":"10.1029/2024JA032994","DOIUrl":"https://doi.org/10.1029/2024JA032994","url":null,"abstract":"<p>An algorithm for obtaining ion vector velocities and neutral winds in the lower thermosphere (100–150 km) was applied to the Sanya incoherent scatter radar (SYISR; located at 18.3°N, 109.6°E) for the first time. The observational experiment transmitted alternating code pulses with a code width of 20 μs. The ion vector velocities and neutral winds were derived from multiple-beam line-of-sight ion velocities. To verify the reliability, we first analyzed the variations and errors of the ion vector velocity and the neutral wind at different time scales. Then, we used an empirical model (HWM) and a theoretical model (NCAR-TIEGCM) for comparison. Both comparisons exhibited good consistency in terms of neutral wind velocity. Furthermore, we compared the SYISR neutral winds with the meteor radar and ICON/MIGHTI winds. The zonal (meridional) wind speeds of the meteor radar and SYISR are 24.95 m/s (13.95 m/s) and 20.68 m/s (16.85 m/s), respectively, at 6:30 LT at 100 km. The amplitudes and phases of the tides derived from the SYISR data are in accordance with those of the meteor radar. The ICON/MIGHTI and SYISR showed consistencies in terms of the wind velocity when ignoring interannual variation.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665045","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}