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| 2022 |
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The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude. Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.058 NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar |
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The hemispherical asymmetry of the low latitude region along 100°E ± 5°E is scrutinized for the year 2015 at magnetically conjugate points on seasonal and intra-seasonal time scales. Two conjugate Ionosonde station pairs are selected- one pair in the inner valley (from SEALION) and the other in the outer edges of the EIA region. The anomaly in the stations is estimated using the difference of low latitude NmF2 from the dip equatorial NmF2 in the same meridian. A monthly average scheme is used instead of a seasonal mean, as the month-to-month variations are found to provide intricate details. The anomaly at the conjugate stations is highly asymmetric even during the equinoctial months of March and October, whereas it is nearly symmetric during April. During June/July, the morning time hemispheric asymmetry (larger on the winter side) temporarily reduces in the midday period and then reverses sign (larger in summer) in the afternoon. The NmF2 observations suggest a close relation of hemispheric symmetry to the position of the subsolar point with respect to the dip equator and a shift/expansion of the trough region of the EIA towards the summer hemisphere. The inter-hemispheric comparison of the hmF2 suggests a strong modulating influence of meridional winds at both the inner and outer stations which depend strongly on the relative position of the subsolar point with respect to the field line geometry. Theoretical (SAMI3/SAMI2) and empirical model (IRI) simulations show a meridional movement of the EIA region with the subsolar point. The winter to summer hemisphere movement of the EIA trough and crest region is also reproduced in the GIM-TEC along 100°E for 2015. This shifting or tailoring of the trough and the crest region is attributed primarily to the meridional wind field, which varies with the shifting position of subsolar point relative to the field line geometry. The seasonal and intra-seasonal difference in the NmF2 hemispheric asymmetry is attributed to the misalignment of the two centers of power viz., the thermospheric/neutral processes and the electromagnetic forces, due to the geographic-geomagnetic offset in this longitude. Kalita, B.; Bhuyan, P.; Nath, S.; Choudhury, M.; Chakrabarty, D.; Wang, K.; Hozumi, K.; Supnithi, P.; Komolmis, T.; . Y. Yatini, C; Le Huy, M.; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.058 NmF2; asymmetry; Conjugate; EIA; model; Hemisphere; hmF2; Subsolar |
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In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (\textless 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus. Yamauchi, Masatoshi; De Keyser, Johan; Parks, George; Oyama, Shin-ichiro; Wurz, Peter; Abe, Takumi; Beth, Arnaud; Daglis, Ioannis; Dandouras, Iannis; Dunlop, Malcolm; Henri, Pierre; Ivchenko, Nickolay; Kallio, Esa; Kucharek, Harald; Liu, Yong; Mann, Ingrid; Marghitu, Octav; Nicolaou, Georgios; Rong, Zhaojin; Sakanoi, Takeshi; Saur, Joachim; Shimoyama, Manabu; Taguchi, Satoshi; Tian, Feng; Tsuda, Takuo; Tsurutani, Bruce; Turner, Drew; Ulich, Thomas; Yau, Andrew; Yoshikawa, Ichiro; Published by: Experimental Astronomy Published on: mar YEAR: 2022 DOI: 10.1007/s10686-022-09846-9 Collision cross-section; Future missions; Low-energy; Neutral gas; Plasma; Voyage 2050 |
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In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (\textless 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus. Yamauchi, Masatoshi; De Keyser, Johan; Parks, George; Oyama, Shin-ichiro; Wurz, Peter; Abe, Takumi; Beth, Arnaud; Daglis, Ioannis; Dandouras, Iannis; Dunlop, Malcolm; Henri, Pierre; Ivchenko, Nickolay; Kallio, Esa; Kucharek, Harald; Liu, Yong; Mann, Ingrid; Marghitu, Octav; Nicolaou, Georgios; Rong, Zhaojin; Sakanoi, Takeshi; Saur, Joachim; Shimoyama, Manabu; Taguchi, Satoshi; Tian, Feng; Tsuda, Takuo; Tsurutani, Bruce; Turner, Drew; Ulich, Thomas; Yau, Andrew; Yoshikawa, Ichiro; Published by: Experimental Astronomy Published on: mar YEAR: 2022 DOI: 10.1007/s10686-022-09846-9 Collision cross-section; Future missions; Low-energy; Neutral gas; Plasma; Voyage 2050 |
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Accurate representation of ionospheric equivalent slab thickness (τ) and scale height (Hm) plays a crucial role in characterizing the complex dynamics of topside and bottomside ionospheric constituents. In the present work, we examined the corresponding morphologies of ionospheric profile parameters with collocated global positioning system (GPS) and Digisonde Portable Sounder (DPS) setups at an equatorial location in west Africa Ilorin (8.50°N, 4.68°E), during a low solar activity year 2010. The extracted τ from GPS and DPS in selected quiet periods confirm it to be a first-order measure of Hm over Africa. The seasonal analysis of τ shows substantial enhancement in the magnitude during the post-sunset and solstice seasons, of which December solstice manifests relatively higher values than June solstice. This result could be associated with the elevation of the meridional wind and drift in the parameters, which are more substantial during the post-noon and solstices. Therefore, at solstices, the post-night increase could indicate solar cycle dynamics during HSA (high solar activity) and LSA (low solar activity). However, the extracted Hm from its relationship with τ did not show visible effects of dynamics in E × B plasma drift and the meridional wind. In our study, a decline in morphologies of Hm and τ from December solstice to June solstice through the equinox is not consistent with the existing observations at mid-latitude. The results would complement the relationships between bottomside and topside profile peak parameters and dynamics of ionospheric constituents for a realistic representation and modeling of the ionosphere over African equatorial and low latitude regions. Thus, it also contributes to the global effort of improving ionospheric prediction and forecasting models. Odeyemi, Olumide; Adeniyi, Jacob; Oyeyemi, Elijah; Panda, Sampad; Jamjareegulgarn, Punyawi; Olugbon, Busola; Oluwadare, Esholomo; Akala, Andrew; Olawepo, Adeniji; Adewale, Adekola; Published by: Advances in Space Research Published on: jan YEAR: 2022 DOI: 10.1016/j.asr.2021.10.030 Global positioning system; Digital portable sounder; Equatorial latitude; Equivalent slab thickness; scale height |
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The ionosphere around the Equatorial Ionization Anomaly (EIA) region exhibits complex dynamics and responds markedly to the solar-magnetospheric energy and momentum. In this paper, the hourly total electron content (TEC) variations in response to the EIA structure in Africa to the 2013 and 2015 St. Patrick’s Day storms is investigated using data obtained from a chain of GPS receivers located in the Africa region. The TEC variations are characterized based on the convective magnetospheric dynamo fields, neutral wind circulation, and zonal electric fields. Generally, the result indicates that the TEC variations are consistent with the different directions of the interplanetary fields during the different phases of the storms. We observed reverse EIA structures in the main phase of the March 2015 storm, likely to be related to the intense PPEF and strong equatorward wind, which imposed a westward zonal electric field at the equator. A similar equatorial peak observed during the recovery phase is associated with DDEF, poleward wind and plasma convergence. Furthermore, the TEC variations also indicate hemispheric asymmetries during the storms. During the main phase of the storm, the TEC variation is more enhanced in the Northern Hemisphere in March 2013 and reverses during March 2015. We observed an equatorial peak during the SSC period in March 2013, while EIA structures are generally weak in March 2015 event. This posit that ionospheric pre-storm behaviour in the EIA region can be better understood when the IMF-Bz and E-field are not significant. The observed distinctive response avowed the peculiarity of the electrodynamics intricacy in the Africa sector. Bolaji, Olawale; Adekoya, Bolarinwa; Adebiyi, Shola; Adebesin, Babatunde; Ikubanni, Stephen; Published by: Astrophysics and Space Science Published on: jan YEAR: 2022 DOI: 10.1007/s10509-021-04022-5 |
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Chapter 4 - Energetic particle dynamics, precipitation, and conductivity This chapter reviews cross-scale coupling and energy transfer in the magnetosphere-ionosphere-thermosphere system via convection, precipitation, and conductance. It begins with an introduction into Earth’s plasma sheet characteristics including particles, plasma moments, and magnetic fields, and their dependence on solar wind and interplanetary magnetic field parameters. Section 4.2 transitions to observations of the magnetosphere convection, precipitation, and coupling with the ionosphere on multiple scales, with Section 4.3 focusing on related global modeling efforts for particle precipitation. This chapter describes basic concepts and principles of major pitch angle scattering processes—wave-particle interactions and field-line curvature scattering—as well as the resulting precipitation and conductance. Section 4.4 continues the discussion started in 4.2 Observations of multiscale convection, precipitation, and conductivity, 4.3 Simulating particle precipitation of magnetospheric origin in global models regarding the resulting ionosphere conductance, delving more deeply into empirical and data assimilative techniques. This chapter describes techniques used over the years to observe and model precipitation and conductance on multiple scales. Gabrielse, Christine; Kaeppler, Stephen; Lu, Gang; Wang, Chih-Ping; Yu, Yiqun; Nishimura, Yukitoshi; Verkhoglyadova, Olga; Deng, Yue; Zhang, Shun-Rong; Published by: Published on: jan YEAR: 2022 DOI: 10.1016/B978-0-12-821366-7.00002-0 Conductance; Conductivity; Convection; particle precipitation |
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The ionospheric response during three distinct geomagnetic storms occurred in the year 2016 is investigated using GPS-TEC observations in the Indian equatorial and low latitude sectors. The three geomagnetic storms are considered for this study which were occurred on 20 January 2016 (2230 LT), 6 March 2016 (0230 LT) and 13 October 2016 (0530 LT) with minimum Sym-H values of −95 nT, −110 nT and −114 nT respectively. These three geomagnetic storms are different from one another in the sustainment of main and recovery phases and are occurred at three different local times corresponding to the Indian longitudes. This study brings out the major differences of these three geomagnetic storms characteristics and their distinct effects on the equatorial and low latitude ionosphere. Significant changes in the VTEC during main and recovery phases of these three storms are found to be mainly associated with prompt penetration electric fields and thermospheric neutral compositional changes. During the storm of 20 January 2016, positive storm effects during main and recovery phases of the storm are in association with the penetration electric fields. The complete main phase for the 6 March 2016 geomagnetic storm was occurred during night time and no changes in VTEC has been identified, which could be due to the weak background electron density. A positive storm effect is noticed during the recovery phases of the storms of 6 March 2016 and 13 October 2016, due to the storm induced electric fields differences and in particular due to the enhanced [O]/[N2] ratio in thermospheric composition. A strong positive storm effect caused by Co-rotating Interacting Region (CIR) induced disturbances after the 13 October 2016 storm is also discussed. Lissa, D.; Venkatesh, K.; Prasad, D.; Niranjan, K.; Published by: Advances in Space Research Published on: aug YEAR: 2022 DOI: 10.1016/j.asr.2022.05.027 Disturbance Dynamo; Geomagnetic storms; Positive Storm Effect; Prompt Penetration Electric Fields (PPEF); Total electron content (TEC) |
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In this study, we investigate the negative ionospheric response over the European sector during two storms that took place on 8 September 2017, primarily, by exploiting observations over ten European locations. The spatial and temporal variations of TEC, foF2 and hmF2 ionospheric characteristics are examined with the aim to explain the physical mechanisms underlying the strong negative ionospheric response. We detected very sharp electron density (in terms of foF2 and TEC) decrease during the main phases of the two storms and we attributed this phenomenon to the large displacement of the Midlatitude Ionospheric Trough (MIT). Our study also revealed that the two storms show different features caused by different processes. In addition, Large Scale Traveling Ionospheric Disturbances (LSTIDs) were observed during both storms, followed by enhanced Spread F conditions over Digisonde stations. The regional dependence of ionospheric storm effects was demonstrated, as the behavior of ionospheric effects over the northern part of Europe differed from that over the southern part. Oikonomou, Christina; Haralambous, Haris; Paul, Ashik; Ray, Sarbany; Alfonsi, Lucilla; Cesaroni, Claudio; Sur, Dibyendu; Published by: Advances in Space Research Published on: aug YEAR: 2022 DOI: 10.1016/j.asr.2022.05.035 Large-scale traveling ionospheric disturbances; Mid-latitude ionospheric trough; September 2017 geomagnetic storm; Swarm satellite |
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We apply a multiresolution Gaussian process model (Lattice Kriging) to combine satellite observations, ground‐based observations, and an empirical auroral model, to produce the Wu, Haonan; Tan, Xiyan; Zhang, Qiong; Huang, Whitney; Lu, Xian; Nishimura, Yukitoshi; Zhang, Yongliang; Published by: Space Weather Published on: YEAR: 2022 DOI: 10.1029/2022SW003146 |
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During geomagnetic storms a large amount of energy is transferred into the ionosphere-thermosphere (IT) system, leading to local and global changes in eg, the dynamics, composition Maute, Astrid; Lu, Gang; Knipp, Delores; Anderson, Brian; Vines, Sarah; Published by: Frontiers in Astronomy and Space Sciences Published on: YEAR: 2022 DOI: 10.3389/fspas.2022.932748 |
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Soft x-ray radiation from the sun is responsible for the production of high energy photoelectrons in the D and E regions of the ionosphere, where they deposit most of their ionization Samaddar, Srimoyee; Venkataramani, Karthik; Yonker, Justin; Bailey, Scott; , others; Published by: arXiv preprint arXiv:2209.11185 Published on: YEAR: 2022 DOI: 10.48550/arXiv.2209.11185 |
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Sounding Rocket Observation of Nitric Oxide in the Polar Night An altitude profile of Nitric Oxide (NO) in the 80–110 km altitude range was measured in the polar night from a sounding rocket on 27 January 2020. The observations were made using the technique of stellar occultation with a UV spectrograph observing the γ (1,0) band of NO near 215 nm. The tangent point for the altitude profile was at 74° latitude, a location that had been in darkness for 80 days. The retrieved slant column density profile is interpreted using an assumed four-parameter analytic profile shape. Retrievals of the fitting parameters yield a profile with a peak NO concentration of 2.2 ± 0.7 × 108 cm−3 at 93.5 ± 4.1 km. The observations were made during a time of minimum solar and geomagnetic activity. The NO maximum retrieved from the rocket profile is significantly larger in abundance and lower in altitude than other observations on the same day at nearby latitudes just outside the polar night. These rocket-borne results are consistent with NO that is created over the course over the polar winter and is confined to high latitudes in the polar night by the mesospheric polar vortex. During the course of that confinement the abundance increases due to the lack of photodissociation, allowing the NO to descend. We show that the observed descent can be explained by eddy diffusion-driven transport, though vertical advection cannot be ruled out. Bailey, Scott; McClintock, William; Carstens, Justin; Thurairajah, Brentha; Das, Saswati; Randall, Cora; Harvey, Lynn; Siskind, David; Stevens, Michael; Venkataramani, Karthik; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA030257 Lower thermosphere; mesosphere; nitric oxide; polar night; sounding rocket; stellar occultation |
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Following the 2022 Tonga Volcano eruption, dramatic suppression and deformation of the equatorial ionization anomaly (EIA) crests occurred in the American sector ∼14,000 km away from the epicenter. The EIA crests variations and associated ionosphere-thermosphere disturbances were investigated using Global Navigation Satellite System total electron content data, Global-scale Observations of the Limb and Disk ultraviolet images, Ionospheric Connection Explorer wind data, and ionosonde observations. The main results are as follows: (a) Following the eastward passage of expected eruption-induced atmospheric disturbances, daytime EIA crests, especially the southern one, showed severe suppression of more than 10 TEC Unit and collapsed equatorward over 10° latitudes, forming a single band of enhanced density near the geomagnetic equator around 14–17 UT, (b) Evening EIA crests experienced a drastic deformation around 22 UT, forming a unique X-pattern in a limited longitudinal area between 20 and 40°W. (c) Thermospheric horizontal winds, especially the zonal winds, showed long-lasting quasi-periodic fluctuations between ±200 m/s for 7–8 hr after the passage of volcano-induced Lamb waves. The EIA suppression and X-pattern merging was consistent with a westward equatorial zonal dynamo electric field induced by the strong zonal wind oscillation with a westward reversal. Aa, Ercha; Zhang, Shun-Rong; Wang, Wenbin; Erickson, Philip; Qian, Liying; Eastes, Richard; Harding, Brian; Immel, Thomas; Karan, Deepak; Daniell, Robert; Coster, Anthea; Goncharenko, Larisa; Vierinen, Juha; Cai, Xuguang; Spicher, Andres; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2022JA030527 EIA suppression and X-pattern; Equatorial ionization anomaly; GNSS TEC; GOLD UV images; ICON MIGHTI neutral wind; Tonga volcano eruption |
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Ionospheric Disturbances and Irregularities during the 25--26 August 2018 Geomagnetic Storm We use ground-based (GNSS, SuperDARN, and ionosondes) and space-borne (Swarm, CSES, and DMSP) instruments to study ionospheric disturbances due to the 25–26 August 2018 geomagnetic storm. The strongest large-scale storm-time enhancements were detected over the Asian and Pacific regions during the main and early recovery phases of the storm. In the American sector, there occurred the most complex effects caused by the action of multiple drivers. At the beginning of the storm, a large positive disturbance occurred over North America at low and high latitudes, driven by the storm-time reinforcement of the equatorial ionization anomaly (at low latitudes) and by particle precipitation (at high latitudes). During local nighttime hours, we observed numerous medium-scale positive and negative ionospheric disturbances at middle and high latitudes that were attributed to a storm-enhanced density (SED)-plume, mid-latitude ionospheric trough, and particle precipitation in the auroral zone. In South America, total electron content (TEC) maps clearly showed the presence of the equatorial plasma bubbles, that, however, were not seen in data of Rate-of-TEC-change index (ROTI). Global ROTI maps revealed intensive small-scale irregularities at high latitudes in both hemispheres within the auroral region. In general, the ROTI disturbance “imaged” quite well the auroral oval boundaries. The most intensive ionospheric fluctuations were observed at low and mid-latitudes over the Pacific Ocean. The storm also affected the positioning accuracy by GPS receivers: during the main phase of the storm, the precise point positioning error exceeded 0.5 m, which is more than five times greater as compared to quiet days. Astafyeva, E.; Yasyukevich, Y.; Maletckii, B.; Oinats, A.; Vesnin, A.; Yasyukevich, A.; Syrovatskii, S.; Guendouz, N.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029843 Geomagnetic storms; Ionosphere; ROTI; ionospheric disturbances; ionospheric irregularities; multi-instrumental approach |
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The Role of Solar Soft X-rays Irradiance in Thermospheric Structure We use a new Atmospheric Chemistry and Energetics one-dimensional (ACE1D) thermospheric model to show that the energies deposited by the solar soft x-rays in the lower Samaddar, Srimoyee; Venkataramani, Karthik; Bailey, Scott; , others; Published by: arXiv preprint arXiv:2209.10543 Published on: YEAR: 2022 DOI: 10.48550/arXiv.2209.10543 |
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A Model of the Globally-averaged Thermospheric Energy Balance Similar to the MSIS data, we bin the GUVI temperatures by latitude It should be noted that GUVI observations at high values of While the GUVI observations cannot be compared directly Venkataramani, Karthik; Bailey, Scott; Samaddar, Srimoyee; Yonker, Justin; Published by: arXiv preprint arXiv:2211.05301 Published on: YEAR: 2022 DOI: 10.48550/arXiv.2211.05301 |
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The present study provides a multi‐instrument analysis of the ionospheric response to the effects of the St. Patrick s Day storm of 17–18 March 2015. Simultaneous observations from 85 Kader, Sk; Dashora, N; Niranjan, K; Published by: Space Weather Published on: YEAR: 2022 DOI: 10.1029/2022SW003157 |
| 2021 |
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Latitudinal Dependence of Ionospheric Responses to Some Geomagnetic Storms during Low Solar Activity The Latitudinal dependence in the response of the Ionospheric F2-layer electron density (NmF2) and peak height (hmF2) to three geomagnetic storms of May and August 2010 has been examined. The data-sets used for the study were obtained from Ilorin, Nigeria (1.87° S/76.67° E), San Vito, Italy (34.68° N/90.38° E), Hermanus, South Africa (42.34° S/82.15° E), and Pruhonice, Czech Republic (45.66° N/90.38° E) geomagnetic coordinates. The quiet time result shows that the rise in NmF2 began earlier at San Vito, followed by Pruhonice. The rate of ionization was observed to be highest in Ilorin, while, the rate of decay in NmF2 is faster at Hermanus. For disturbed NmF2 condition, remarkable similarities in the NmF2 responses during geomagnetic storms were recorded from Hermanus in the mid-latitude and Ilorin, an equatorial station. NmF2 enhancements (\textgreater6 hours) that is consistent with the increase in hmF2 were observed at all the mid-latitude stations during the main phase of the 02 May, 2010 storm, without any noticeable change over ILN. Similarly, 12 hours of positive phase was observed at ILN and HMN, with 30 hours of NmF2 depletions at PRN and SVT during the recovery phase. ILN is in the equatorial Trough, so most of the NmF2 produced at this region is lifted to the higher latitudes by the fountain effect during the main phase. The suppression of the zonal electric field at ILN is responsible for the NmF2 enhancement during the recovery phase, while the mid-latitude responses have been attributed to the effect of the thermospheric winds and neutral composition changes. Joshua, B.; Adeniyi, J.; Olawepo, A.; Rabiu, Babatunde; Daniel, Okoh; Adebiyi, S.; Adebesin, B.; Ikubanni, S.; Abdurahim, B.; Published by: Geomagnetism and Aeronomy Published on: may YEAR: 2021 DOI: 10.1134/S0016793221030063 Electric field; Electron density; Geomagnetic storms; magnetosphere; peak height |
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Latitudinal Dependence of Ionospheric Responses to Some Geomagnetic Storms during Low Solar Activity The Latitudinal dependence in the response of the Ionospheric F2-layer electron density (NmF2) and peak height (hmF2) to three geomagnetic storms of May and August 2010 has been examined. The data-sets used for the study were obtained from Ilorin, Nigeria (1.87° S/76.67° E), San Vito, Italy (34.68° N/90.38° E), Hermanus, South Africa (42.34° S/82.15° E), and Pruhonice, Czech Republic (45.66° N/90.38° E) geomagnetic coordinates. The quiet time result shows that the rise in NmF2 began earlier at San Vito, followed by Pruhonice. The rate of ionization was observed to be highest in Ilorin, while, the rate of decay in NmF2 is faster at Hermanus. For disturbed NmF2 condition, remarkable similarities in the NmF2 responses during geomagnetic storms were recorded from Hermanus in the mid-latitude and Ilorin, an equatorial station. NmF2 enhancements (\textgreater6 hours) that is consistent with the increase in hmF2 were observed at all the mid-latitude stations during the main phase of the 02 May, 2010 storm, without any noticeable change over ILN. Similarly, 12 hours of positive phase was observed at ILN and HMN, with 30 hours of NmF2 depletions at PRN and SVT during the recovery phase. ILN is in the equatorial Trough, so most of the NmF2 produced at this region is lifted to the higher latitudes by the fountain effect during the main phase. The suppression of the zonal electric field at ILN is responsible for the NmF2 enhancement during the recovery phase, while the mid-latitude responses have been attributed to the effect of the thermospheric winds and neutral composition changes. Joshua, B.; Adeniyi, J.; Olawepo, A.; Rabiu, Babatunde; Daniel, Okoh; Adebiyi, S.; Adebesin, B.; Ikubanni, S.; Abdurahim, B.; Published by: Geomagnetism and Aeronomy Published on: may YEAR: 2021 DOI: 10.1134/S0016793221030063 Electric field; Electron density; Geomagnetic storms; magnetosphere; peak height |
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Latitudinal Dependence of Ionospheric Responses to Some Geomagnetic Storms during Low Solar Activity The Latitudinal dependence in the response of the Ionospheric F2-layer electron density (NmF2) and peak height (hmF2) to three geomagnetic storms of May and August 2010 has been examined. The data-sets used for the study were obtained from Ilorin, Nigeria (1.87° S/76.67° E), San Vito, Italy (34.68° N/90.38° E), Hermanus, South Africa (42.34° S/82.15° E), and Pruhonice, Czech Republic (45.66° N/90.38° E) geomagnetic coordinates. The quiet time result shows that the rise in NmF2 began earlier at San Vito, followed by Pruhonice. The rate of ionization was observed to be highest in Ilorin, while, the rate of decay in NmF2 is faster at Hermanus. For disturbed NmF2 condition, remarkable similarities in the NmF2 responses during geomagnetic storms were recorded from Hermanus in the mid-latitude and Ilorin, an equatorial station. NmF2 enhancements (\textgreater6 hours) that is consistent with the increase in hmF2 were observed at all the mid-latitude stations during the main phase of the 02 May, 2010 storm, without any noticeable change over ILN. Similarly, 12 hours of positive phase was observed at ILN and HMN, with 30 hours of NmF2 depletions at PRN and SVT during the recovery phase. ILN is in the equatorial Trough, so most of the NmF2 produced at this region is lifted to the higher latitudes by the fountain effect during the main phase. The suppression of the zonal electric field at ILN is responsible for the NmF2 enhancement during the recovery phase, while the mid-latitude responses have been attributed to the effect of the thermospheric winds and neutral composition changes. Joshua, B.; Adeniyi, J.; Olawepo, A.; Rabiu, Babatunde; Daniel, Okoh; Adebiyi, S.; Adebesin, B.; Ikubanni, S.; Abdurahim, B.; Published by: Geomagnetism and Aeronomy Published on: may YEAR: 2021 DOI: 10.1134/S0016793221030063 Electric field; Electron density; Geomagnetic storms; magnetosphere; peak height |
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In this paper, echo occurrence rates for the Dome C East (DCE) and the new Dome C North (DCN) radars are studied. We report the ionospheric and ground scatter echo occurrence rates for selected periods around equinoxes and solstices in the final part of the solar cycle XXIV. The occurrence maps built in Altitude Adjusted Corrected Geomagnetic latitude and Magnetic Local Time coordinates show peculiar patterns highly variable with season. The comparisons of the radar observations with the International Reference Ionosphere model electron density and with ray tracing simulations allow us to explain the major features of observed patterns in terms of electron density variations. The study shows the great potential of the DCE and DCN radar combination to the Super Dual Auroral Radar Network (SuperDARN) convection mapping in terms of monitoring key regions of the high-latitude ionosphere critical for understanding of the magnetospheric dynamics. Marcucci, Maria; Coco, Igino; Massetti, Stefano; Pignalberi, Alessio; Forsythe, Victoriya; Pezzopane, Michael; Koustov, Alexander; Longo, Simona; Biondi, David; Simeoli, Enrico; Consolini, Giuseppe; Laurenza, Monica; Marchaudon, Aurélie; Satta, Andrea; Cirioni, Alessandro; De Simone, Angelo; Olivieri, Angelo; Baù, Alessandro; Salvati, Alberto; Published by: Polar Science Published on: jun YEAR: 2021 DOI: 10.1016/j.polar.2021.100684 |
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In this paper, echo occurrence rates for the Dome C East (DCE) and the new Dome C North (DCN) radars are studied. We report the ionospheric and ground scatter echo occurrence rates for selected periods around equinoxes and solstices in the final part of the solar cycle XXIV. The occurrence maps built in Altitude Adjusted Corrected Geomagnetic latitude and Magnetic Local Time coordinates show peculiar patterns highly variable with season. The comparisons of the radar observations with the International Reference Ionosphere model electron density and with ray tracing simulations allow us to explain the major features of observed patterns in terms of electron density variations. The study shows the great potential of the DCE and DCN radar combination to the Super Dual Auroral Radar Network (SuperDARN) convection mapping in terms of monitoring key regions of the high-latitude ionosphere critical for understanding of the magnetospheric dynamics. Marcucci, Maria; Coco, Igino; Massetti, Stefano; Pignalberi, Alessio; Forsythe, Victoriya; Pezzopane, Michael; Koustov, Alexander; Longo, Simona; Biondi, David; Simeoli, Enrico; Consolini, Giuseppe; Laurenza, Monica; Marchaudon, Aurélie; Satta, Andrea; Cirioni, Alessandro; De Simone, Angelo; Olivieri, Angelo; Baù, Alessandro; Salvati, Alberto; Published by: Polar Science Published on: jun YEAR: 2021 DOI: 10.1016/j.polar.2021.100684 |
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We present a joint analysis of longitude-temporal variations of ionospheric and geomagnetic parameters at middle and high latitudes in the Northern Hemisphere during the two severe magnetic storms in March and June 2015 by using data from the chains of magnetometers, ionosondes and GPS/GLONASS receivers. We identify the fixed longitudinal zones where the variability of the magnetic field is consistently high or low under quiet and disturbed geomagnetic conditions. The revealed longitudinal structure of the geomagnetic field variability in quiet geomagnetic conditions is caused by the discrepancy of the geographic and magnetic poles and by the spatial anomalies of different scales in the main magnetic field of the Earth. Variations of ionospheric parameters are shown to exhibit a pronounced longitudinal inhomogeneity with changing geomagnetic conditions. This inhomogeneity is associated with the longitudinal features of background and disturbed structure of the geomagnetic field. During the recovery phase of a storm, important role in dynamics of the mid-latitude ionosphere may belong to wave-like thermospheric disturbances of molecular gas, propagating westward for several days. Therefore, it is necessary to extend the time interval for studying the ionospheric effects of strong magnetic storms by a few days after the end of the magnetospheric source influence, while the disturbed regions in the thermosphere continues moving westward and causes the electron density decrease along the trajectories of propagation. Chernigovskaya, M.; Shpynev, B.; Yasyukevich, A.; Khabituev, D.; Ratovsky, K.; Belinskaya, Yu.; Stepanov, A.; Bychkov, V.; Grigorieva, S.; Panchenko, V.; Kouba, D.; Mielich, J.; Published by: Advances in Space Research Published on: jan YEAR: 2021 DOI: 10.1016/j.asr.2020.10.028 Chain of GPS/GLONASS receivers; Geomagnetic field variations; geomagnetic storm; Ionosonde chain; ionospheric disturbances |
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\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater Coincident auroral far-ultraviolet (FUV) and ground-based ionosonde observations are compared for the purpose of determining whether auroral FUV remote sensing algorithms that assume pure electron precipitation are biased in the presence of proton precipitation. Auroral particle transport and optical emission models, such as the Boltzmann 3-Constituent (B3C) model, predict that maximum E region electron density (NmE) values derived from auroral Lyman–Birge–Hopfield (LBH) emissions, assuming electron precipitation, will be biased by up to \textlessspan class="inline-formula"\textgreater∼20\textless/span\textgreater \% (high) for pure proton aurora, while comparisons between LBH radiances and radiances derived from in situ particle flux observations (i.e., Knight et al., 2008, 2012) indicate that the bias associated with proton aurora should be much larger. Surprisingly, in the comparisons with ionosonde observations described here, no bias associated with proton aurora is found in FUV-derived auroral NmE, which means that auroral FUV remote sensing methods for NmE are more accurate in the presence of proton precipitation than was suggested in the aforementioned earlier works. Possible explanations for the discrepancy with the earlier results are discussed.\textless/p\textgreater Published by: Annales Geophysicae Published on: jan YEAR: 2021 DOI: 10.5194/angeo-39-105-2021 |
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Proton Aurora and Optical Emissions in the Subauroral Region Optical structures located equatorward of the main auroral oval often exhibit different morphologies and dynamics than structures at higher latitudes. In some cases, questions arise regarding the formation mechanisms of these photon-emitting phenomena. New developments in space and ground-based instruments have enabled us to acquire a clearer view of the processes playing a role in the formation of subauroral structures. In addition, the discovery of new optical structures helps us improve our understanding of the latitudinal and altitudinal coupling that takes place in the subauroral region. However, several questions remain unanswered, requiring the development of new instruments and analysis techniques. We discuss optical phenomena in the subauroral region, summarize observational results, present conclusions about their origin, and pose a number of open questions that warrant further investigation of proton aurora, detached subauroral arcs and spots, stable auroral red (SAR) arcs, and STEVE (Strong Thermal Emission Velocity Enhancement). Gallardo-Lacourt, B.; Frey, H.; Martinis, C.; Published by: Space Science Reviews Published on: jan YEAR: 2021 DOI: 10.1007/s11214-020-00776-6 |
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This paper demonstrates and assesses the capability of the advanced three-dimensional (3-D) ionosphere tomography technique, during severe conditions. The study area is northeast Asia and quasi-Japan-centred. Reconstructions are based on total electron content data from a dense ground-based global navigation satellite system receiver network and parameters from operational ionosondes. We used observations from ionosondes, Swarm satellites and radio occultation (RO) to assess the 3-D picture. Specifically, we focus on St. Patrick’s day geomagnetic storm (17–19 March 2015), the most intense in solar cycle 24. During this event, the energy ingested into the ionosphere resulted in Dst and Kp and reaching values \textasciitilde − 223 nT and 8, respectively, and the region of interest, the East Asian sector, was characterized by a \textasciitilde 60\% reduction in electron densities. Results show that the reconstructed densities follow the physical dynamics previously discussed in earlier publications about storm events. Moreover, even when ionosonde data were not available, the technique could still provide a consistent picture of the ionosphere vertical structure. Furthermore, analyses show that there is a profound agreement between the RO profiles/in-situ densities and the reconstructions. Therefore, the technique is a potential candidate for applications that are sensitive to ionospheric corrections. Nicholas, Ssessanga; Mamoru, Yamamoto; Susumu, Saito; Published by: Earth, Planets and Space (Online) Published on: dec YEAR: 2021 DOI: 10.1186/s40623-021-01447-8 geomagnetic storm; Ground-GNSS-STEC tomography; Ionosonde data assimilation |
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The Global-scale Observations of the Limb and Disk (GOLD) mission, launched in 2018, aims to investigate the low latitude ionosphere from a geostationary orbit at 47.5°W. It uses two identical spectrometers measuring the wavelength range from 134.0 to 163.0 nm. The configuration of the Earth s magnetic field shows that the largest offset between geographic and geomagnetic equators occurs in the longitude sectors sampled by GOLD. In an attempt to investigate the longitude dependence of the occurrence rate and time of onset of plasma bubbles, or plasma depletions, GOLD data were separated in three sectors: 65°-55°W, 50°-40°W, and 10°W–0°. Observations of the nighttime emissions in 135.6 nm on November 2018 and March 2019 show plasma depletions occurring very frequently at these longitudes. The growth rate of the Rayleigh-Taylor instability was computed at these longitudes under similar low solar activity conditions, assuming an empirical model of upward plasma drifts. The time and value of the maximum growth rates obtained cannot always explain the observations. On average, the observed occurrence rate of plasma depletions is high, with a maximum of 73\% (observed during November 2018 at ∼45°W). Most of the depletions observed in November at 45°W and 60°W occur within 1 h after sunset. When compared with the November 2018 observations, depletions in March 2019 occur at later times. Martinis, C.; Daniell, R.; Eastes, R.; Norrell, J.; Smith, J.; Klenzing, J.; Solomon, S.; Burns, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028510 F region; longitude variability; plasma bubbles; Plasma depletions; upward drifts |
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The Global-scale Observations of the Limb and Disk (GOLD) mission, launched in 2018, aims to investigate the low latitude ionosphere from a geostationary orbit at 47.5°W. It uses two identical spectrometers measuring the wavelength range from 134.0 to 163.0 nm. The configuration of the Earth s magnetic field shows that the largest offset between geographic and geomagnetic equators occurs in the longitude sectors sampled by GOLD. In an attempt to investigate the longitude dependence of the occurrence rate and time of onset of plasma bubbles, or plasma depletions, GOLD data were separated in three sectors: 65°-55°W, 50°-40°W, and 10°W–0°. Observations of the nighttime emissions in 135.6 nm on November 2018 and March 2019 show plasma depletions occurring very frequently at these longitudes. The growth rate of the Rayleigh-Taylor instability was computed at these longitudes under similar low solar activity conditions, assuming an empirical model of upward plasma drifts. The time and value of the maximum growth rates obtained cannot always explain the observations. On average, the observed occurrence rate of plasma depletions is high, with a maximum of 73\% (observed during November 2018 at ∼45°W). Most of the depletions observed in November at 45°W and 60°W occur within 1 h after sunset. When compared with the November 2018 observations, depletions in March 2019 occur at later times. Martinis, C.; Daniell, R.; Eastes, R.; Norrell, J.; Smith, J.; Klenzing, J.; Solomon, S.; Burns, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028510 F region; longitude variability; plasma bubbles; Plasma depletions; upward drifts |
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A method for retrieving temperature and composition from 150 to 350 km in Earth s thermosphere using total number density measurements made via extreme ultraviolet (EUV) solar occultations by the Project for OnBoard Autonomy 2/Large Yield Radiometer (PROBA2/LYRA) instrument is presented. Systematic and random uncertainties are calculated and found to be less than 5\% for the temperature measurements and 5\%–20\% for the composition measurements. Regression coefficients relating both temperature and the [O]/[N2] abundance ratio with EUV irradiance at 150, 275, and 350 km are reported. Additionally, it is shown that the altitude where [O] equals [N2] decreases with increasing solar EUV irradiance, an effect attributed to thermal expansion. Temperatures from 2010 to 2017 are compared with estimates from the MSIS empirical model and show good agreement at the dawn terminator but LYRA is markedly cooler at the dusk terminator, with the MSIS-LYRA temperature difference increasing with solar activity. Anthropogenic cooling can explain this discrepancy at periods of lower solar activity, but the divergence of temperature with increasing solar activity remains unexplained. LYRA measurements of the exospheric temperature sensitivity to EUV irradiance are compared with contemporaneous measurements made at Mars, showing that the exospheric temperature at Mars is approximately half as sensitive to EUV variability as that of Earth. Thiemann, Edward; Dominique, Marie; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029262 comparative planetology; EUV; occultations; space weather; thermosphere |
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Santa Maria Digisonde data are used for the first time to investigate the F region behavior during a geomagnetic storm. The August 25, 2018 storm is considered complex due to the incidence of two Interplanetary Coronal Mass Ejections and a High-Speed Solar Wind Stream (HSS). The F 2 layer critical frequency (f o F 2) and its peak height (h m F 2) collected over Santa Maria, near the center of the South American Magnetic Anomaly (SAMA), are compared with data collected from Digisondes installed in the Northern (NH) and Southern (SH) Hemispheres in the American sector. The deviation of f o F 2 (Df o F 2) and h m F 2 (Dh m F 2) are used to quantify the ionospheric storm effects. Different F region responses were observed during the main phase (August 25–26), which is attributed to the traveling ionospheric disturbances and disturbed eastward electric field during nighttime. The F region responses became highly asymmetric between the NH and SH at the early recovery phase (RP, August 26) due to a combination of physical mechanisms. The observed asymmetries are interpreted as caused by modifications in the thermospheric composition and a rapid electrodynamic mechanism. The persistent enhanced thermospheric [O]/[N2] ratio observed from August 27 to 29 combined with the increased solar wind speed induced by the HSS and IMF B z fluctuations seem to be effective in causing the positive ionospheric storm effects and the shift of the Equatorial Ionization Anomaly crest to higher than typical latitudes. Consequently, the most dramatic positive ionospheric storm during the RP occurred over Santa Maria (∼120\%). Moro, J.; Xu, J.; Denardini, C.; Resende, L.; Neto, P.; Da Silva, L.; Silva, R.; Chen, S.; Picanço, G.; Carmo, C.; Liu, Z.; Yan, C.; Wang, C.; Schuch, N.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028663 Digisonde; Equatorial ionization anomaly; F-region; Ionospheric storm; SAMA; space weather |
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The local, regional, and global morphology of the ionospheric response of the March 2015 geomagnetic storm has been investigated by different studies. However, the spatio-temporal evolution of the drivers of the global ionospheric response to this storm has not yet been investigated, using multi-data sources, in detail. Therefore, in this study drivers of the ionospheric response to the March 17–18, 2015 storm are investigated. Spatial and temporal variations of deposition of solar wind energy are found to be the cause for hemispherical asymmetry of the response of the ionosphere; the American-Canada-Greenland sector, Northern Hemisphere high-latitude ionosphere responded about 12 h earlier than the Southern Hemisphere (SH) high-latitude ionosphere, resulted from hemispherical energy imbalance as detected from Hemispherical Power. The positive ionospheric storm observed in the high-latitude regions is found to be due to solar wind energy deposition at high latitudes. Interestingly, it is found that the Northern hemisphere ionospheric positive storm shifted to the mid-latitude and disappeared there whereas the SH ionospheric positive storm shifted to mid-latitude and then farther to the low-latitude with time; this spatio-temporal evaluation of positive ionospheric storm is found to be due to the spatio-temporal enhancement of the O/N2 ratio. Also, the mid (Europe-African)and low (Brazilian) latitudes positive ionospheric storms prevailed due to prompt penetration electric fields, disturbance dynamo electric fields, and enhancement of the O/N2 ratio. Moreover, the negative ionospheric storm, observed at the NH high and mid-latitudes in the American and Asian sectors, is linked to the reduction of the O/N2 ratio. Terefe, Dejene; Nigussie, Melessew; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029348 |
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Progresses and Challenges to specifying the IT system during weak storms Deng, Yue; Heelis, Roderick; Paxton, Larry; Lyons, Larry; Nishimura, Toshi; Zhang, Shunrong; Bristow, Bill; Maute, Astrid; Sheng, Cheng; Zhu, Qingyu; , others; Published by: Published on: |
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Observations of far-ultraviolet (FUV) dayglow by the Global-scale Observations of Limb and Disk (GOLD) mission provide a new opportunity to monitor relative composition changes in the upper atmosphere as well as solar extreme ultraviolet (EUV) variability. Relative composition changes are quantified by ΣO/N2, the column density ratio of atomic oxygen to molecular nitrogen, while QEUV provides a measure of the solar EUV energy flux from 1 to 45 nm into the upper atmosphere. This spectral range provides the ionizing radiation which ultimately results in FUV airglow emission produced by photodissociation and photoelectron impact. The quantities ΣO/N2 and QEUV are derived from GOLD FUV observations through lookup tables that are constructed using a first-principles photoelectron transport model. The two FUV emissions used are O I 135.6 nm and the N2 Lyman-Birge-Hopfield (LBH) bands. We present an overview of the theoretical basis for the algorithms and practical considerations for application to GOLD data. The effects of uncertainties in electron impact cross sections, off-nadir viewing, and instrument artifacts are reviewed. We also discuss GOLD Level 1C DAY, Level 2 data products ON2 and QEUV, and present representative samples of each. Correira, J.; Evans, J.; Lumpe, J.; Krywonos, A.; Daniell, R.; Veibell, V.; McClintock, W.; Eastes, R.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029517 GOLD; neutral composition; ON2; QEUV; radiative recombination; thermosphere |
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The geomagnetic storm that occurred on 25 August 25 2018, that is, during the minimum of solar cycle 24, is currently the strongest ever probed by the first China Seismo-Electromagnetic Satellite (CSES-01). By integrating the in situ measurements provided by CSES-01 (orbiting at altitude of 507 km) and by Swarm A satellite (orbiting at ca., 460 km) with ground-based observations (ionosondes, magnetometers, and Global Navigation Satellite System receivers), we investigate the ionospheric response at lower- and mid-latitudes over Brazil. Specifically, we investigate the electrodynamic disturbances driven by solar wind changes, by focusing on the disturbances driving modifications of the equatorial electrojet (EEJ). Our proposed multisensor technique analysis mainly highlights the variations in the topside and bottomside ionosphere, and the interplay between prompt penetrating electric fields and disturbance dynamo electric fields resulting in EEJ variations. Thanks to this approach and leveraging on the newly available CSES-01 data, we complement and extend what recently investigated in the Western South American sector, by highlighting the significant longitudinal differences, which mainly come from the occurrence of a daytime counter-EEJ during both 25 and 26 August at Braziliian longitudes and during part of 26 August only in the Peruvian sector. In addition, the increased thermospheric circulation driven by the storm has an impact on the EEJ during the recovery phase of the storm. The observations at the CSES-01/Swarm altitudes integrated with the ground-based observation recorded signatures of equatorial ionospheric anomaly crests formation and modification during daytime coupled with the positive ionospheric storm effects at midlatitude. Spogli, L.; Sabbagh, D.; Regi, M.; Cesaroni, C.; Perrone, L.; Alfonsi, L.; Di Mauro, D.; Lepidi, S.; Campuzano, S.; Marchetti, D.; De Santis, A.; Malagnini, A.; Scotto, C.; Cianchini, G.; Shen, Xu; Piscini, A.; Ippolito, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028368 Geomagnetic storms; Equatorial Electrojet; in situ plasma density; ionospheric elctroduamics; Ionospheric storms; low-latitude ionosphere |
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The geomagnetic storm that occurred on 25 August 25 2018, that is, during the minimum of solar cycle 24, is currently the strongest ever probed by the first China Seismo-Electromagnetic Satellite (CSES-01). By integrating the in situ measurements provided by CSES-01 (orbiting at altitude of 507 km) and by Swarm A satellite (orbiting at ca., 460 km) with ground-based observations (ionosondes, magnetometers, and Global Navigation Satellite System receivers), we investigate the ionospheric response at lower- and mid-latitudes over Brazil. Specifically, we investigate the electrodynamic disturbances driven by solar wind changes, by focusing on the disturbances driving modifications of the equatorial electrojet (EEJ). Our proposed multisensor technique analysis mainly highlights the variations in the topside and bottomside ionosphere, and the interplay between prompt penetrating electric fields and disturbance dynamo electric fields resulting in EEJ variations. Thanks to this approach and leveraging on the newly available CSES-01 data, we complement and extend what recently investigated in the Western South American sector, by highlighting the significant longitudinal differences, which mainly come from the occurrence of a daytime counter-EEJ during both 25 and 26 August at Braziliian longitudes and during part of 26 August only in the Peruvian sector. In addition, the increased thermospheric circulation driven by the storm has an impact on the EEJ during the recovery phase of the storm. The observations at the CSES-01/Swarm altitudes integrated with the ground-based observation recorded signatures of equatorial ionospheric anomaly crests formation and modification during daytime coupled with the positive ionospheric storm effects at midlatitude. Spogli, L.; Sabbagh, D.; Regi, M.; Cesaroni, C.; Perrone, L.; Alfonsi, L.; Di Mauro, D.; Lepidi, S.; Campuzano, S.; Marchetti, D.; De Santis, A.; Malagnini, A.; Scotto, C.; Cianchini, G.; Shen, Xu; Piscini, A.; Ippolito, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028368 Geomagnetic storms; Equatorial Electrojet; in situ plasma density; ionospheric elctroduamics; Ionospheric storms; low-latitude ionosphere |
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The geomagnetic storm that occurred on 25 August 25 2018, that is, during the minimum of solar cycle 24, is currently the strongest ever probed by the first China Seismo-Electromagnetic Satellite (CSES-01). By integrating the in situ measurements provided by CSES-01 (orbiting at altitude of 507 km) and by Swarm A satellite (orbiting at ca., 460 km) with ground-based observations (ionosondes, magnetometers, and Global Navigation Satellite System receivers), we investigate the ionospheric response at lower- and mid-latitudes over Brazil. Specifically, we investigate the electrodynamic disturbances driven by solar wind changes, by focusing on the disturbances driving modifications of the equatorial electrojet (EEJ). Our proposed multisensor technique analysis mainly highlights the variations in the topside and bottomside ionosphere, and the interplay between prompt penetrating electric fields and disturbance dynamo electric fields resulting in EEJ variations. Thanks to this approach and leveraging on the newly available CSES-01 data, we complement and extend what recently investigated in the Western South American sector, by highlighting the significant longitudinal differences, which mainly come from the occurrence of a daytime counter-EEJ during both 25 and 26 August at Braziliian longitudes and during part of 26 August only in the Peruvian sector. In addition, the increased thermospheric circulation driven by the storm has an impact on the EEJ during the recovery phase of the storm. The observations at the CSES-01/Swarm altitudes integrated with the ground-based observation recorded signatures of equatorial ionospheric anomaly crests formation and modification during daytime coupled with the positive ionospheric storm effects at midlatitude. Spogli, L.; Sabbagh, D.; Regi, M.; Cesaroni, C.; Perrone, L.; Alfonsi, L.; Di Mauro, D.; Lepidi, S.; Campuzano, S.; Marchetti, D.; De Santis, A.; Malagnini, A.; Scotto, C.; Cianchini, G.; Shen, Xu; Piscini, A.; Ippolito, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028368 Geomagnetic storms; Equatorial Electrojet; in situ plasma density; ionospheric elctroduamics; Ionospheric storms; low-latitude ionosphere |
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The geomagnetic storm that occurred on 25 August 25 2018, that is, during the minimum of solar cycle 24, is currently the strongest ever probed by the first China Seismo-Electromagnetic Satellite (CSES-01). By integrating the in situ measurements provided by CSES-01 (orbiting at altitude of 507 km) and by Swarm A satellite (orbiting at ca., 460 km) with ground-based observations (ionosondes, magnetometers, and Global Navigation Satellite System receivers), we investigate the ionospheric response at lower- and mid-latitudes over Brazil. Specifically, we investigate the electrodynamic disturbances driven by solar wind changes, by focusing on the disturbances driving modifications of the equatorial electrojet (EEJ). Our proposed multisensor technique analysis mainly highlights the variations in the topside and bottomside ionosphere, and the interplay between prompt penetrating electric fields and disturbance dynamo electric fields resulting in EEJ variations. Thanks to this approach and leveraging on the newly available CSES-01 data, we complement and extend what recently investigated in the Western South American sector, by highlighting the significant longitudinal differences, which mainly come from the occurrence of a daytime counter-EEJ during both 25 and 26 August at Braziliian longitudes and during part of 26 August only in the Peruvian sector. In addition, the increased thermospheric circulation driven by the storm has an impact on the EEJ during the recovery phase of the storm. The observations at the CSES-01/Swarm altitudes integrated with the ground-based observation recorded signatures of equatorial ionospheric anomaly crests formation and modification during daytime coupled with the positive ionospheric storm effects at midlatitude. Spogli, L.; Sabbagh, D.; Regi, M.; Cesaroni, C.; Perrone, L.; Alfonsi, L.; Di Mauro, D.; Lepidi, S.; Campuzano, S.; Marchetti, D.; De Santis, A.; Malagnini, A.; Scotto, C.; Cianchini, G.; Shen, Xu; Piscini, A.; Ippolito, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028368 Geomagnetic storms; Equatorial Electrojet; in situ plasma density; ionospheric elctroduamics; Ionospheric storms; low-latitude ionosphere |
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This paper reports that plasma density depletions appearing at middle latitudes near sunrise survived until afternoon on 29 May 2017 during the recovery phase of a geomagnetic storm. By analyzing GPS data collected in Japan, we investigate temporal variations in the horizontal two-dimensional distribution of total electron content (TEC) during the geomagnetic storm. The SYM-H index reached −142 nT around 08 UT on 28 May 2017. TEC depletions extending up to approximately 38°N along the meridional direction appeared over Japan around 05 LT (LT = UT + 9 hours) on 29 May 2017, when TEC rapidly increased at sunrise due to the solar extreme ultraviolet (EUV) radiation. The TEC depletions appeared sequentially over Japan for approximately 8 hours in sunlit conditions. At 06 LT on 29 May, when the plasma depletions first appeared over Japan, the background TEC was enhanced to approximately 17 TECU, and then decreased to approximately 80\% of the TEC typical of magnetically quiet conditions. We conclude that this temporal variation of background plasma density in the ionosphere was responsible for the persistence of these plasma depletions for so long in daytime. By using the Naval Research Laboratory: Sami2 is Another Model of the Ionosphere (SAMI2), we have evaluated how plasma production and ambipolar diffusion along the magnetic field may affect the rate of plasma depletion disappearance. Simulation shows that the plasma density increases at the time of plasma depletion appearance; subsequent decreases in the plasma density appear to be responsible for the long-lasting persistence of plasma depletions during daytime. The plasma density depletion in the top side ionosphere is not filled by the plasma generated by the solar EUV productions because plasma production occurs mainly at the bottom side of the ionosphere. Otsuka, Yuichi; Shinbori, Atsuki; Sori, Takuya; Tsugawa, Takuya; Nishioka, Michi; Huba, Joseph; Published by: Earth and Planetary Physics Published on: YEAR: 2021 DOI: 10.26464/epp2021046 Ionosphere; GPS; ionospheric irregularity; plasma bubble; SAMI2 |
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Statistical Analysis of Throat Aurora Using Long Term DMSP/SSUSI Observation Throat aurora is believed to be associated with magnetopause indentations and has direct implications on magnetopause reconnection. In this study, for the first time, we use Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager observations over ∼14 years to characterize the throat aurora occurrence, latitudinal extent, seasonal, and its solar cycle dependence. We identified 386 throat aurora cases during the different passes of the satellite over the northern hemisphere. The latitudinal extent of these throat aurorae are estimated and are divided into small, medium, and large categories. The small and medium latitudinal extent throat aurorae account for about 91\% of the total cases. The throat aurorae are found to occur most frequently in the post-noon hours. The throat aurorae were also observed more frequently during winter, likely due to summer-winter asymmetry in the ionospheric conductance. The occurrence of the throat aurora is also found to be anti-correlated with the solar cycle, likely because low solar activity gives good chances for sporadic reconnection that favors the occurrence of throat aurora. The dependence on interplanetary magnetic field reveals positive Bx favoring the occurrence of throat aurora. It also shows positive Bx (negative By) supports pre-noon (post-noon) occurrence. The difference in the trend and average values of background interplanetary magnetic field conditions with the throat aurora confirms the favorable conditions for the occurrence of throat aurora. Selvakumaran, R.; Han, De-Sheng; Gokani, Sneha; Zhang, Y.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029164 |
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At the nadir, there are ∼57.5 pixels per averaging area for GUVI and ∼28.5 for SSUSI. Only 0.030 counts per R per averaging area for GUVI, F16 SSUSI, and F18 SSUSI, respectively. Published by: Published on: YEAR: 2021 DOI: 10.5194/angeo-39-105-2021 |
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Recent attention has been given to mesoscale phenomena across geospace (∼10 s km to 500 km in the ionosphere or ∼0.5 RE to several RE in the magnetosphere), as their contributions to the system global response are important yet remain uncharacterized mostly due to limitations in data resolution and coverage as well as in computational power. As data and models improve, it becomes increasingly valuable to advance understanding of the role of mesoscale phenomena contributions—specifically, in magnetosphere-ionosphere coupling. This paper describes a new method that utilizes the 2D array of Time History of Events and Macroscale Interactions during Substorms (THEMIS) white-light all-sky-imagers (ASI), in conjunction with meridian scanning photometers, to estimate the auroral scale sizes of intense precipitating energy fluxes and the associated Hall conductances. As an example of the technique, we investigated the role of precipitated energy flux and average energy on mesoscales as contrasted to large-scales for two back-to-back substorms, finding that mesoscale aurora contributes up to ∼80\% (∼60\%) of the total energy flux immediately after onset during the early expansion phase of the first (second) substorm, and continues to contribute ∼30–55\% throughout the remainder of the substorm. The average energy estimated from the ASI mosaic field of view also peaked during the initial expansion phase. Using the measured energy flux and tables produced from the Boltzmann Three Constituent (B3C) auroral transport code (Strickland et al., 1976; 1993), we also estimated the 2D Hall conductance and compared it to Poker Flat Incoherent Scatter Radar conductance values, finding good agreement for both discrete and diffuse aurora. Gabrielse, Christine; Nishimura, Toshi; Chen, Margaret; Hecht, James; Kaeppler, Stephen; Gillies, Megan; Reimer, Ashton; Lyons, Larry; Deng, Yue; Donovan, Eric; Evans, Scott; Published by: Frontiers in Physics Published on: |
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This chapter reviews fundamental properties and recent advances of diffuse and pulsating aurora. Diffuse and pulsating aurora often occurs on closed field lines and involves energetic electron precipitation by wave-particle interaction. After summarizing the definition, large-scale morphology, types of pulsation, and driving processes, we review observation techniques, occurrence, duration, altitude, evolution, small-scale structures, fast modulation, relation to high-energy precipitation, the role of ECH waves, reflected and secondary electrons, ionosphere dynamics, and simulation of wave-particle interaction. Finally we discuss open questions of diffuse and pulsating aurora. Nishimura, Yukitoshi; Lessard, Marc; Katoh, Yuto; Miyoshi, Yoshizumi; Grono, Eric; Partamies, Noora; Sivadas, Nithin; Hosokawa, Keisuke; Fukizawa, Mizuki; Samara, Marilia; Michell, Robert; Kataoka, Ryuho; Sakanoi, Takeshi; Whiter, Daniel; Oyama, Shin-ichiro; Ogawa, Yasunobu; Kurita, Satoshi; Published by: Space Science Reviews Published on: 01/2020 YEAR: 2020 DOI: 10.1007/s11214-019-0629-3 |
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An outstanding issue in the general circulation model simulations for Earth\textquoterights upper atmosphere is the inaccurate estimation of Joule heating, which could be associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. The binning methods used to develop those empirical models may contribute to the inaccuracy. Traditionally, data are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is not considered and therefore the forcing patterns may be significantly smeared. To avoid the smoothing issue, data can be binned according to some physically important boundaries in the high-latitude forcing, that is, through a boundary-oriented binning approach. In this study, we have investigated the sensitivity of high-latitude forcing patterns to the binning methods by applying both static and boundary-oriented binning approaches to the electron precipitation and electric potential data from the Defense Meteorological Satellite Program satellites. For this initial study, we have focused on the moderately strong and dominantly southward interplanetary magnetic field conditions. As compared with the static binning results, the boundary-oriented binning approach can provide a more confined and intense electron precipitation pattern. In addition, the magnitudes of the electric potential and electric field in the boundary-oriented binning results increase near the convection reversal boundary, leading to a ~11\% enhancement of the cross polar cap potential. The forcing patterns obtained from both binning approaches are used to drive the Global Ionosphere and Thermosphere Model to assess the impacts on Joule heating by using different binning patterns. It is found that the hemispheric-integrated Joule heating in the simulation driven by the boundary-oriented binning patterns is 18\% higher than that driven by the static binning patterns. Zhu, Qingyu; Deng, Yue; Richmond, Arthur; Maute, Astrid; Chen, Yun-Ju; Hairston, Marc; Kilcommons, Liam; Knipp, Delores; Redmon, Robert; Mitchell, Elizabeth; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2020 YEAR: 2020 DOI: 10.1029/2019JA027270 Electric field; high latitude; Joule heating; particle precipitation |
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Major geomagnetic storms are caused by un-usually intense solar wind southward magnetic fields thatimpinge upon the Earth\textquoterights magnetosphere (Dungey, 1961).How can we predict the occurrence of future interplanetary events? Do we currently know enough of the underlying physics and do we have sufficient observations of solar wind phenomena that will impinge upon the Earth\textquoterights magnetosphere? We view this as the most important challenge in space weather. We discuss the case for magnetic clouds (MCs), interplanetary sheaths upstream of interplanetary coronal mass ejections (ICMEs), corotating interactionregions (CIRs) and solar wind high-speed streams (HSSs).The sheath- and CIR-related magnetic storms will be difficult to predict and will require better knowledge of the slow solar wind and modeling to solve. For interplanetaryspace weather, there are challenges for understanding the fluences and spectra of solar energetic particles (SEPs). This will require better knowledge of interplanetary shock properties as they propagate and evolve going from the Sun to1 AU (and beyond), the upstream slow solar wind and energetic \textquotedblleftseed\textquotedblright particles. Dayside aurora, triggering of night-side substorms, and formation of new radiation belts can all be caused by shock and interplanetary ram pressure impingements onto the Earth\textquoterights magnetosphere. The acceleration and loss of relativistic magnetospheric \textquotedblleftkiller\textquotedblright electronsand prompt penetrating electric fields in terms of causingpositive and negative ionospheric storms are reasonably well understood, but refinements are still needed. The forecasting of extreme events (extreme shocks, extreme solar energeticparticle events, and extreme geomagnetic storms (Carrington events or greater)) are also discussed. Energetic particle precipitation into the atmosphere and ozone destructionare briefly discussed. For many of the studies, the Parker Solar Probe, Solar Orbiter, Magnetospheric Multiscale Mission(MMS), Arase, and SWARM data will be useful. Tsurutani, Bruce; Lakhina, Gurbax; Hajra, Rajkumar; Published by: Nonlinear Processes in Geophysics Published on: 01/2020 YEAR: 2020 DOI: 10.5194/npg-27-75-2020 |
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Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Chernigovskaya, MA; Shpynev, BG; Yasyukevich, AS; Khabituev, DS; Published by: Published on: |
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Unprecedented hemispheric asymmetries during a surprise ionospheric storm: A game of drivers Astafyeva, Elvira; Bagiya, Mala; Förster, Matthias; Nishitani, Nozomu; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Karan, Deepak; Daniell, Robert; England, Scott; Martinis, Carlos; Eastes, Richard; Burns, Alan; McClintock, William; Published by: Journal of Geophysical Research: Space Physics Published on: |