S. Tian, J. Li, C.-P. Wang, Q. Ma, J. Bortnik, C. P. Ferradas, J. Liu, Y. Shen, L. R. Lyons
{"title":"Kinetic Alfven Waves Driving Auroral O+ Ion Outflows to Form Plasma Cloak During the 17 March 2015 Geomagnetic Storm","authors":"S. Tian, J. Li, C.-P. Wang, Q. Ma, J. Bortnik, C. P. Ferradas, J. Liu, Y. Shen, L. R. Lyons","doi":"10.1029/2024JA033169","DOIUrl":"https://doi.org/10.1029/2024JA033169","url":null,"abstract":"<p>We present multi-platform observations of plasma cloak, O+ outflows, kinetic Alfven waves (KAWs), and auroral oval for the geomagnetic storm on 17 March 2015. During the storm's main phase, we observed a generally symmetric equatorward motion of the auroral oval in both hemispheres, corresponding to the plasmasphere erosion and inward motion of the plasma sheet. Consequently, Van Allen Probes became immersed within the plasma sheet for extended hours and repeatedly observed correlated KAWs and O+ outflows. The KAWs contain adequate energy flux toward the ionosphere to energize the observed outflow ions. Adiabatic particle tracing suggests that the O+ outflows are directly from the nightside auroral oval and that the energization is through a quasi-static potential drop. The O+ outflows from the nightside auroral oval were adequate (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>8</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $1{0}^{8}$</annotation>\u0000 </semantics></math>-<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>9</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $1{0}^{9}$</annotation>\u0000 </semantics></math> #/<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow>\u0000 <mi>c</mi>\u0000 <mi>m</mi>\u0000 </mrow>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{c}mathrm{m}}^{2}$</annotation>\u0000 </semantics></math>-s) and prompt (several minutes) to explain the newly formed plasma cloak, suggesting that they were a dominant initial source of plasma cloak during this storm.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143116152","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}
Yu-Lun Liou, Katariina Nykyri, Xuanye Ma, Robert Cuéllar
{"title":"Statistical Study of the Solar Wind Current Sheet Properties: Defining Instrument Requirements for the Seven Sisters Mission Concept","authors":"Yu-Lun Liou, Katariina Nykyri, Xuanye Ma, Robert Cuéllar","doi":"10.1029/2024JA032610","DOIUrl":"https://doi.org/10.1029/2024JA032610","url":null,"abstract":"<p>The present study performs a procedure of estimating the current sheet (CS) thickness in the solar wind. Motivated by the science requirements for a multi-spacecraft solar wind mission called the Seven Sisters, this research aims to address the required temporal resolution of the magnetometer in order to entirely encompass the observations of thin CSs. Additionally, this procedure can contribute to addressing the unresolved turbulence heating problem in the solar wind. We have statistically provided the solar wind CS thickness estimated, with full instrumental resolution of 128 Hz, from the Flux Gate magnetometer (FGM) data of the Magnetospheric Multiscale (MMS) mission. Out of 183 cases of solar wind CS crossings, the thicknesses varied from 0.1 to 3 Mm with a maximum of 32.97 s, minimum of 0.16 s and average of 3.08 s crossing time. Of these, 73.22% of the CSs can be identified by using 1-Hz measurement cadence, while 12.5 Hz data can fully identify all of the CSs. Therefore, it can be concluded that the 1-Hz sampling rate is sufficient for the survey mode, while the sampling frequency of 12.5 Hz as the burst mode is capable of achieving even the strictest scientific objectives. Our statistical results also report a population below 100 km or <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <msub>\u0000 <mi>d</mi>\u0000 <mi>i</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> $1{d}_{i}$</annotation>\u0000 </semantics></math>, which should be further examined.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115916","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}
Brian J. Harding, Mateo Cardona Serrano, L. Claire Gasque, Yen-Jung Joanne Wu, Astrid Maute, Thomas J. Immel
{"title":"Wind-Driven Variability in the Prereversal Enhancement of the Equatorial Vertical Plasma Drift: Climatologies Observed by ICON","authors":"Brian J. Harding, Mateo Cardona Serrano, L. Claire Gasque, Yen-Jung Joanne Wu, Astrid Maute, Thomas J. Immel","doi":"10.1029/2024JA033279","DOIUrl":"https://doi.org/10.1029/2024JA033279","url":null,"abstract":"<p>The prereversal enhancement (PRE) is a brief surge in upward plasma velocity in the evening equatorial ionosphere and a driver of equatorial spread-F. This study reports the first PRE climatology from Ionospheric Connection Explorer (ICON) data, exhibiting seasonal and longitudinal variability that is qualitatively consistent with results from two previous satellite missions. Previous missions, however, lacked the neutral wind observations to characterize their impact on the PRE. To quantitatively assess wind impacts, numerical experiments are performed with a standalone dynamo solver using winds from the TIEGCM-ICON, which is driven from below by observed tides. To quantify the impact of solar/magnetic geometry, such as the alignment between the solar terminator and the magnetic meridian, the model was first driven with seasonally and longitudinally averaged winds (which includes seasonally averaged zonal-mean winds and migrating tides). This reproduces the observed PRE variability with a correlation of 0.44. Incorporating longitudinally and seasonally varying wind patterns improves the correlation to 0.68. This suggests that climatological wind variability is an important driver of PRE variability, but future work is needed to account for the missing variability. Potential missing drivers include conductivity variability near the terminator and mesoscale wind features such as the solar terminator wave.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033279","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115933","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}
Cristian R. Radulescu, Andrew J. Coates, Sven Simon, Daniel Verscharen, Geraint H. Jones
{"title":"Pick-Up ion Distributions in the Inner and Middle Saturnian Magnetosphere","authors":"Cristian R. Radulescu, Andrew J. Coates, Sven Simon, Daniel Verscharen, Geraint H. Jones","doi":"10.1029/2024JA033390","DOIUrl":"https://doi.org/10.1029/2024JA033390","url":null,"abstract":"<p>Based on the entire dataset collected by the Cassini Plasma Spectrometer, we provide a comprehensive picture of the pitch angle (PA) and velocity distributions of pick-up ions (PUIs) in Saturn's inner and middle magnetosphere. We investigate the dependence of these distributions on Saturnian Local Time and magnetic latitude. We also search for correlations with the signatures of ion cyclotron waves (ICWs) observed by the Cassini magnetometer. Our survey reveals that ion PA distributions have a pancake shape and their full width increases monotonically with magnetic latitude. This increase in angular width is anti-correlated with the observed amplitudes of ICWs that are generated during the thermalization of the PUI distribution. We find no evidence of the previously observed, non-monotonic change of wave amplitudes with magnetic latitude mapping into the width of the PA distributions. This suggests that only a small fraction of the energy deposited into the waves is transferred back to the ions to broaden the distribution. We find that the PA scattering time is several times the bounce period, meaning PUIs become PA scattered only after completing several cycles of bounce motion and, hence migrating to higher latitudes by the time they become more isotropic. When moving away from Saturn's magnetic equatorial plane, the observed half-width of the velocity distributions does not evolve appreciably with latitude and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 </mrow>\u0000 <annotation> $L$</annotation>\u0000 </semantics></math> shell value. This behavior changes only outside the orbit of Rhea where the observed velocity distributions begin to broaden due to elevated plasma temperatures.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033390","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115975","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":"Subauroral Polarization Streams Effects on the Low-Latitude Ionosphere During the Geomagnetic Storm on 17 March 2015","authors":"Tianyu Cao, Jing Liu, Shuhan Li, Kedeng Zhang","doi":"10.1029/2024JA033050","DOIUrl":"https://doi.org/10.1029/2024JA033050","url":null,"abstract":"<p>The equatorial ionization anomaly (EIA) is the salient feature of the low-latitude ionosphere, characterized by two crests around magnetic latitudes ±15° and one trough around the dip equator. The effects of the subauroral polarization streams (SAPS) on EIA are rarely studied, impairing our understanding of high- and low-latitude ionospheric coupling during geomagnetic storms. In this work, we deploy the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) with an empirical SAPS model and GPS observed total electron content (TEC) to identify the SAPS effects on the EIA during the geomagnetic storm on 17 March 2015. Our results show that the low-latitude TEC (∼±20° magnetic latitudes and 12–16 LT) is enhanced by 5 TECU (∼5%) due to SAPS effects. This enhancement is found at both the crests and trough of EIA. A term-by-term analysis of the ion continuity equation is performed in TIEGCM. The SAPS-induced equatorward winds (∼30 m/s) are the most important in producing electron density enhancement at the topside ionosphere. The ionosphere is lifted to higher altitudes where the chemical recombination is slower, causing the TEC and electron density enhancement. However, at the bottomside F-layer ionosphere, the electron density enhancement is dominated by the downward E × B drifts (∼5 m/s) driven by SAPS.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115974","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":"Do the Vertical Movements of the Peak Height of F Region Truly Represent the Vertical \u0000 \u0000 \u0000 E\u0000 ×\u0000 B\u0000 \u0000 $mathbf{E}times mathbf{B}$\u0000 Plasma Drift Velocity Over the Dip Equator?","authors":"Arya Ashok, K. M. Ambili, R. K. Choudhary","doi":"10.1029/2024JA033202","DOIUrl":"https://doi.org/10.1029/2024JA033202","url":null,"abstract":"<p>This study examines the reasons for the difference observed between the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>E</mi>\u0000 <mo>×</mo>\u0000 <mi>B</mi>\u0000 </mrow>\u0000 <annotation> $mathbf{E}times mathbf{B}$</annotation>\u0000 </semantics></math> plasma drift and the drift calculated by tracing the movement of the ionospheric <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>F</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${F}_{2}$</annotation>\u0000 </semantics></math> region peak, using a quasitwo-dimensional theoretical ionospheric model. Analysis shows that vertical drift causes the electron density profiles in the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>F</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${F}_{2}$</annotation>\u0000 </semantics></math> region to steepen, where photochemistry dominates, and pushes the plasma to higher altitudes. Photochemical processes result in the lower peak <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <mrow>\u0000 <mi>h</mi>\u0000 <mi>m</mi>\u0000 <msub>\u0000 <mi>F</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left(hm{F}_{2}right)$</annotation>\u0000 </semantics></math>, while the upper peak <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mi>h</mi>\u0000 <mi>p</mi>\u0000 <mi>F</mi>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation> $(hpF)$</annotation>\u0000 </semantics></math> is attributed to vertical drift, which is difficult to trace due to diffusion effects. The close agreement between model-derived <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Δ</mi>\u0000 <mi>h</mi>\u0000 <mi>p</mi>\u0000 <mi>F</mi>\u0000 <mo>/</mo>\u0000 <mi>Δ</mi>\u0000 <mi>t</mi>\u0000 </mrow>\u0000 <annotation> ${Delta }hpF/{Delta }t$</annotation>\u0000 </semantics></math> and Scherliess-Fejer (SF) vertical drifts confirms that the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>F</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 ","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"130 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115113","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}