Journal of Geophysical Research: Space Physics最新文献

{"title":"A Statistical Examination of the Spatial Correlations of HF Ionospheric Absorption Signatures Using the GO-Canada Riometer Network","authors":"R. G. Gillies,&nbsp;E. Spanswick,&nbsp;S. Skone","doi":"10.1029/2023JA032082","DOIUrl":"https://doi.org/10.1029/2023JA032082","url":null,"abstract":"<p>A network of 30-MHz riometers distributed across Canada have been monitoring auroral absorption for decades. Electron precipitation can cause enhanced densities to develop below ∼100 km where the higher neutral density can cause absorption of High Frequency (HF) signals. Modeling D-region absorption accurately can be challenging due to the large distances between riometer monitoring sites. It is of interest to develop an understanding of the typical scale sizes of these regions for assimilation in ionospheric models. Using the entire network of GO-Canada riometers, auroral absorption events may be monitored as they develop through a wide MLT sector. By examining correlations between sites, proxies for the scale sizes of absorption regions may be estimated. It was found that the sizes of the absorbing regions in the zonal direction are on the order of 900 km. Conversely, the characteristic scale sizes of the regions in the meridional direction were ∼700 km. These results are consistent with the general magnetospheric structure which sees higher energy electrons primarily present in the nightside transition region, and ring current. This creates a natural limit in latitudinal correlations, while the spread in longitude is likely connected to the size of precipitation regions in MLT. Our results also show significant spread in scale sizes in both directions from a few hundred to several thousand km. In this paper, we summarize these results in terms of the observed trends in high energy electron precipitation spatial and temporal scales and discuss future work to connect these scales to magnetospheric drivers.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JA032082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642276","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":"Variation of the Altitude of Auroral Emission During a Substorm Cycle: Stereoscopic Optical Observations During the LAMP Rocket Experiment","authors":"K. Hosokawa,&nbsp;Y. Miyoshi,&nbsp;M. Mcharg,&nbsp;V. Ledvina,&nbsp;D. Hampton,&nbsp;M. Lessard,&nbsp;M. Shumko,&nbsp;K. Asamura,&nbsp;T. Sakanoi,&nbsp;T. Mitani,&nbsp;T. Namekawa,&nbsp;M. Nosé,&nbsp;Y. Ogawa,&nbsp;A. Jaynes,&nbsp;A. Halford","doi":"10.1029/2024JA033036","DOIUrl":"https://doi.org/10.1029/2024JA033036","url":null,"abstract":"<p>We estimated the altitude of aurora by combining data from all-sky cameras at multiple places which were obtained during the LAMP sounding rocket experiment in Alaska on 5 March 2022. During the launch window of the rocket, three high-speed all-sky cameras were operative at three stations immediately below the trajectory of the rocket: Poker Flat, Venetie and Fort Yukon. The all-sky cameras captured all-sky images with a temporal resolution of 100 Hz (80 Hz for the Fort Yukon case). The method of altitude determination is based on analyses of time-series of the optical intensity obtained from the all-sky cameras in Venetie and Poker Flat covering the downrange area of the rocket trajectory. The estimated altitude of pulsating aurora during the rocket experiment was found to be consistent with that derived from the in-situ observation of precipitating electrons with a model of optical emission, which confirms the feasibility of deriving the emission altitude through correlation analyses using time-series. The estimated altitude of aurora decreased after the expansion onset of the substorm and stayed slightly below 100 km during the interval of pulsating aurora in the recovery phase. In particular, prompt and brief lowering of the auroral emission, well down to around 90 km, was detected during a transition of auroral form from discrete to diffuse which occurred ∼10 min after the onset. This result implies an existence of a process causing harder electron precipitation operative soon after the start of the expansion phase of auroral substorm.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641740","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":"Significant Midlatitude Plasma Density Peaks and Dual-Hemisphere SED During the 10–11 May 2024 Super Geomagnetic Storm","authors":"Ercha Aa,&nbsp;Shun-Rong Zhang,&nbsp;Jiuhou Lei,&nbsp;Fuqing Huang,&nbsp;Philip J. Erickson,&nbsp;Anthea J. Coster,&nbsp;Bingxian Luo","doi":"10.1029/2024JA033360","DOIUrl":"https://doi.org/10.1029/2024JA033360","url":null,"abstract":"<p>This study investigates midlatitude ionospheric variations during the super geomagnetic storm on 10–11 May 2024, utilizing multi-instrument data from ground-based sources (Global Navigation Satellite Systems receivers and a Fabry–Perot Interferometer) and space-based measurements (Swarm and DMSP). We observed several distinct density gradient structures in the midlatitude ionosphere, with the main findings summarized as follows: (a) Significant zonal plasma density enhancements developed continuously in local dusk across the American-Pacific-Asian longitude sectors around <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 <mn>40</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $pm 40{}^{circ}$</annotation>\u0000 </semantics></math> geomagnetic latitude. These midlatitude peaks exhibited a wide longitudinal extension exceeding 150<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math> and a prolonged duration of 12–15 hr during the late main phase and early recovery phase of the storm. (b) Strong storm-enhanced density (SED) was observed in both hemispheres yet with different longitudinal and universal time preferences. In the Northern Hemisphere, significant SED occurred over the American longitude sector during 20:30–22:30 UT on May 10. In the Southern Hemisphere, pronounced SED was observed not only in the American longitudes during 20:30–22:30 UT on May 10 but also in the Australian longitude sector during 02:00–04:00 UT on May 11.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033360","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641863","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":"Measurements of F1- Region Ionosphere State Variables at Arecibo Through Quasi Height-Independent Exhaustive Fittings of the Incoherent Scatter Ion-Line Spectra","authors":"Yanlin Li,&nbsp;Qihou Zhou","doi":"10.1029/2024JA032620","DOIUrl":"https://doi.org/10.1029/2024JA032620","url":null,"abstract":"<p>We discuss an exhaustive search approach to fit the incoherent scatter spectrum (ISS) in the F₁-region for molecular ion fraction (<i>f</i>_<i>m</i>), ion temperature (<i>T</i>_<i>i</i>), and electron temperature (<i>T</i>_<i>e</i>). The commonly used “full profile” approach for F₁-region measurements parameterizes the molecular ion fraction as a function of altitude and fits all the related heights for the state variables. In our approach, we fit the ISS at each height for <i>f</i>_<i>m</i>, <i>T</i>_<i>i</i>, <i>T</i>_<i>e</i>, and ion velocity (<i>V</i>_<i>i</i>) independently. Our exhaustive search method finds all the major local minima at each altitude. Although a parameterized function is used to guide the algorithm in finding the best solution, the fitting parameters retain their local characteristics. Despite that fitting <i>f</i>_<i>m</i>, <i>T</i>_<i>i</i>, and <i>T</i>_<i>e</i> without constraints requires Doppler shift to be accurately determined and the ISS signal-to-noise ratio higher than the full-profile method, simulations show that <i>T</i>_<i>i</i>, <i>T</i>_<i>e</i>, and <i>f</i>_<i>m</i> can be recovered within a few percent accuracy with a moderate signal-to-noise ratio. We apply the exhaustive search approach to the Arecibo high-resolution incoherent scatter radar data taken on 13 September 2014. The derived ion and electron temperatures are sensitive enough to reveal thermosphere gravity waves commonly seen in the electron density previously. Our method is more robust than previous height-independent fitting methods. Comparison with another Arecibo program indicates our results are likely more accurate. Simultaneous high-resolution measurements of <i>T</i>_<i>i</i>, <i>T</i>_<i>e</i>, <i>f</i>_<i>m</i>, <i>V</i>_<i>i</i>, and electron concentration (<i>N</i>_<i>e</i>) in our approach open new opportunities for synergistic studies of the F₁-region dynamics and chemistry.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical Properties of Quasi-Periodic Electromagnetic Ion Cyclotron Waves: ULF Modulation Effects","authors":"Muhammad Shahid,&nbsp;M. Fraz Bashir,&nbsp;A. V. Artemyev,&nbsp;X.-J. Zhang,&nbsp;Vassilis Angelopoulos,&nbsp;G. Murtaza","doi":"10.1029/2023JA032290","DOIUrl":"https://doi.org/10.1029/2023JA032290","url":null,"abstract":"&lt;p&gt;Electromagnetic ion cyclotron (EMIC) waves effectively scatter relativistic electrons in Earth's radiation belts and energetic ions in the ring current. Empirical models parameterizing the EMIC wave characteristics are important elements of inner magnetosphere simulations. Two main EMIC wave populations included in such simulations are the population generated by plasma sheet injections and another population generated by magnetospheric compression due to the solar wind. In this study, we investigate a third class of EMIC waves, generated by hot plasma sheet ions modulated by compressional ultra-low frequency (ULF) waves. Such ULF-modulated EMIC waves are mostly observed on the dayside, between magnetopause and the outer radiation belt edge. We show that ULF-modulated EMIC waves are weakly oblique (with a wave normal angle &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;mn&gt;2&lt;/mn&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;mo&gt;±&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&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; ${approx} 2{0}^{{circ}}pm 1{0}^{{circ}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and narrow-banded (with a spectral width of &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;mn&gt;1&lt;/mn&gt;\u0000 &lt;mo&gt;/&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${sim} 1/3$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; of the mean frequency). We construct an empirical model of the EMIC wave characteristics as a function of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;L&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $L$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;-shell and MLT. The low ratio of electron plasma frequency to electron gyrofrequency &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;msub&gt;\u0000 &lt;mi&gt;f&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;p&lt;/mi&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;/&lt;/mo&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;mo&gt;∼&lt;/mo&gt;\u0000 &lt;mn&gt;5&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641864","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":"Buoyancy Modes in a Low Entropy Bubble","authors":"F. R. Toffoletto,&nbsp;R. A. Wolf,&nbsp;J. Derr","doi":"10.1029/2024JA032714","DOIUrl":"https://doi.org/10.1029/2024JA032714","url":null,"abstract":"<p>In the nightside region of Earth's magnetosphere, braking oscillations or buoyancy modes have been associated with the occurrence of low entropy bubbles. These bubbles form in the plasma sheet, particularly during geomagnetically disturbed times, and because of interchange, move rapidly earthward and may eventually come to rest in the inner plasma sheet or inner magnetosphere. Upon arrival, they often exhibit damped oscillations with periods of a few minutes and are associated with Pi2 pulsations. Previously we used the thin filament approximation to compare the frequencies and modes of buoyancy waves using magnetohydrodynamic (MHD) ballooning and classic interchange theory. Interchange oscillations differ from the more general MHD oscillations by assuming constant pressure along a magnetic field line. It was determined that MHD ballooning and interchange modes are similar for plasma sheet field lines but differ for field lines that map to the inner magnetosphere. This suggested that the classic interchange formulation was only valid in the plasma sheet. This paper tests the hypothesis that the agreement between MHD ballooning and classic interchange could be restored inside a bubble. We create a small region of entropy depletion in the magnetotail and compare the buoyancy mode properties. At some locations inside the bubble, the MHD ballooning buoyancy modes resemble interchange modes but with lower frequencies than those of the unperturbed background. Unstable modes are found on the earthward edge of the bubble, while at the tailward edge, MHD ballooning predicts a slow mode wave solution not seen in the pure interchange solution.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032714","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641420","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":"Local Time and Hemispheric Asymmetries of Field-Aligned Currents and Polar Electrojet During May 2024 Superstorm Periods","authors":"Hui Wang,&nbsp;Qihang Cheng,&nbsp;Hermann Lühr,&nbsp;Yunfang Zhong,&nbsp;Kedeng Zhang,&nbsp;Hao Xia","doi":"10.1029/2024JA033020","DOIUrl":"https://doi.org/10.1029/2024JA033020","url":null,"abstract":"<p>This study examines field-aligned currents (FACs) and polar electrojet (PEJ) characteristics during the extreme May 2024 geomagnetic storms across dawn, dusk, daytime, and nighttime in both hemispheres. FACs and PEJ intensities were up to 9 times greater than usual, with equatorward FACs reaching −44° Magnetic Latitude. Maximum FACs and PEJ are larger at dawn than dusk in the Northern Hemisphere but larger at dusk than at dawn in the Southern Hemisphere. Dawn and duskside FACs correlate best with Dst or solar wind dynamic pressure (Pd) in both hemispheres. On the dayside (nightside), most FACs in both hemispheres are primarily correlated with Pd (merging electric field, Em or Pd). The PEJs correlate largely with Dst and partly with Em and Pd. Duskside (nighttime) currents are located at lower latitudes than dawnside (daytime), and northern currents are positioned more poleward than southern currents. The latitudes of peak FACs are most strongly correlated with Dst or Pd in both hemispheres. However, in the northern daytime sector, they are primarily influenced by Em. The latitudes of peak PEJ show the strongest correlation with Dst or Pd in both hemispheres, except on the northern dawnside, where they are primarily influenced by Em. The qualitative relationships between peak current density, corresponding latitude, solar wind parameters, and the Dst index are derived.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of the Inner Magnetospheric Electric Field on Plasma Sheet Access","authors":"C. P. Ferradas,&nbsp;S. A. Thaller,&nbsp;M.-C. Fok,&nbsp;G. D. Reeves,&nbsp;B. A. Larsen","doi":"10.1029/2024JA033030","DOIUrl":"https://doi.org/10.1029/2024JA033030","url":null,"abstract":"<p>This study presents observations of the large-scale electric field and H⁺ fluxes over the entire Van Allen Probes mission duration. These observations are used to determine the spatial distributions of the azimuthal component of the ExB drift velocity and the plasma sheet H⁺ pressure, and their geomagnetic activity dependence. To investigate the influence of the inner magnetospheric electric field on H⁺ plasma sheet access, the boundary of zero azimuthal ExB drift velocity (BZEB) is identified as a proxy of the inner extent of the convection electric field and its characteristics are compared with that of the inner edge of the H⁺ plasma sheet (H⁺ IEPS). We find that the large-scale convection electric field has a dominant role on H⁺ plasma sheet access. This is evidenced by the good correlation between the BZEB and the H⁺ IEPS. Both boundaries present overall deeper access with increasing <i>Kp</i>. Moreover, both boundaries exhibit a similar deeper access on the evening sector compared to the afternoon sector, and both boundaries are more closely collocated in L for moderate and high <i>Kp</i>, while for low <i>Kp</i> the H⁺ IEPS is located at lower L than the BZEB. Furthermore, the collocation of both boundaries in L is better in the evening sector than in the afternoon sector, where the H⁺ IEPS lies farther inward in the afternoon sector for all <i>Kp</i> levels. This implies that the afternoon sector is the preferred region of the overlap between the hot ion plasma sheet and the cold plasmasphere.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641204","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":"Characteristics of Longitudinal Discontinuity Over Nighttime Equatorial Ionization Anomaly Crests With Multiple Observations","authors":"Jiawen Chen,&nbsp;Jiahao Zhong,&nbsp;Xuguang Cai,&nbsp;Yongqiang Hao,&nbsp;Lei Cai,&nbsp;Xin Wan,&nbsp;Qiaoling Li,&nbsp;Zijing Tang,&nbsp;Xingyan Song,&nbsp;Hao Han,&nbsp;Jiawei Kuai,&nbsp;Lujin Cai","doi":"10.1029/2024JA033133","DOIUrl":"https://doi.org/10.1029/2024JA033133","url":null,"abstract":"<p>Longitudinal discontinuity is observed over nighttime equatorial ionization anomaly (EIA) crests, characterized by a significant depletion between longitudes. Multiple observations, especially GOLD 135.6-nm airglow images, are used to investigate the EIA discontinuity in details. Discontinuity events are found more likely to occur in one hemisphere, with a longitudinal width of tens of degrees and prolonged durations of several hours from 19 to 24 LT. The plasma depletion is most conspicuous at low altitudes, near or below the peak height. For the Atlantic sector, the EIA discontinuity is most prevalent between the March Equinox and the September Equinox, with an equinoctial asymmetry of higher occurrence rates around September Equinox. The climatological results indicate that field-aligned trans-hemispheric wind plays a predominant role in promoting the discontinuity, which transports the plasma from one hemisphere to the other hemisphere, resulting in potential localized depletion over the EIA crest.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641205","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":"Multi-Instrument Approach to Study Polarization Jet/SAID and STEVE","authors":"A. A. Sinevich,&nbsp;A. A. Chernyshov,&nbsp;D. V. Chugunin,&nbsp;M. V. Klimenko,&nbsp;V. A. Panchenko,&nbsp;G. A. Yakimova,&nbsp;A. V. Timchenko,&nbsp;W. J. Miloch,&nbsp;M. M. Mogilevsky","doi":"10.1029/2024JA033222","DOIUrl":"https://doi.org/10.1029/2024JA033222","url":null,"abstract":"<p>In this study, we employ a unique multi-instrumental approach for a comprehensive examination of Polarization Jet (PJ) (or, another name, Subauroral Ion Drift (SAID)). A diverse set of data is used to assess the connection between the appearance of the inhomogeneous structure of PJ/SAID and its reflection in ground-based observations during geomagnetic activity. Our approach combines satellite (Defense Meteorological Satellite Program, NorSat-1, Swarm) and ground-based (ionosondes, magnetometers, GPS/GLONASS receivers) data, allowing us to study PJ/SAID in detail and compare satellite data with ground-based measurements. We describe the characteristic patterns on ionograms that may indicate the presence of PJ/SAID and how ionosondes can be used to study PJ/SAID. Polarization Jet Strata and irregularities of plasma parameters can cause multiple reflections, which are visible in ionograms as F-spread. The splitting of the F2 trace into two or more traces on ionograms may indicate the presence of PJ/SAID near the observation point. Data from GPS/GLONASS receivers in regions where PJ/SAID is observed enable the construction of local total electron content maps, visualizing how PJ/SAID is reflected in those maps. It is shown how the geomagnetic latitude of PJ/SAID changes during the geomagnetic activity. Furthermore, this case is notable because not only PJ/SAID but also STEVE (Strong Thermal Emission Velocity Enhancement) is observed at subauroral latitudes in Northern Europe during the examined geomagnetic event.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 11","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142641351","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}