Bibliography
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Found 624 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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An extensive intercomparison of ionospheric foF2 observations and NCAR Thermosphere-Ionosphere ElectrodynamicsGeneral Circulation Model(TIE-GCM)simulations has been carried out for the dip equatorial location of Thiruvananthapuram. Ionosonde measurements for geomagnetically quiet days of 2002, 2006 and 2008, representing solar maximum, solar minimum and deep solar minimum conditions have been used for the analysis. In general TIE-GCM simulations reproduced the temporal and seasonal characteristics of foF2 over Thiruvananthapuram reasonably well for all the three solar activity conditions. Seasonally the difference between the measured and the simulated foF2 tended to be higher during winter (maximum of 25\%). Additionally, it is found that TIE-GCM is not reproducing the reduction in the foF2 values in the noon hours i.e. the bite out, which is very prominent in the foF2 observations predominantly during 2002. A detailed analysis revealed that, there is good agreement between the modeled and measured values for the whole observation period, with an R value of 0.81. From the comparison it is clear that the model underestimates the observations in general but for the periods when bite out is prominent, the model gives an over estimation. The comprehensive comparisons during different solar activity conditions have shown that the difference between modeled and measured ionospheric peak densities lies in the range of. 10 to −25\%. This study brings out the efficacy of the model in simulating the temporal seasonal and solar cycle variability of ionospheric foF2 over the equatorial Indian region. Mridula, N.; Manju, G.; Sijikumar, S.; Pant, Tarun; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.018 |
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An extensive intercomparison of ionospheric foF2 observations and NCAR Thermosphere-Ionosphere ElectrodynamicsGeneral Circulation Model(TIE-GCM)simulations has been carried out for the dip equatorial location of Thiruvananthapuram. Ionosonde measurements for geomagnetically quiet days of 2002, 2006 and 2008, representing solar maximum, solar minimum and deep solar minimum conditions have been used for the analysis. In general TIE-GCM simulations reproduced the temporal and seasonal characteristics of foF2 over Thiruvananthapuram reasonably well for all the three solar activity conditions. Seasonally the difference between the measured and the simulated foF2 tended to be higher during winter (maximum of 25\%). Additionally, it is found that TIE-GCM is not reproducing the reduction in the foF2 values in the noon hours i.e. the bite out, which is very prominent in the foF2 observations predominantly during 2002. A detailed analysis revealed that, there is good agreement between the modeled and measured values for the whole observation period, with an R value of 0.81. From the comparison it is clear that the model underestimates the observations in general but for the periods when bite out is prominent, the model gives an over estimation. The comprehensive comparisons during different solar activity conditions have shown that the difference between modeled and measured ionospheric peak densities lies in the range of. 10 to −25\%. This study brings out the efficacy of the model in simulating the temporal seasonal and solar cycle variability of ionospheric foF2 over the equatorial Indian region. Mridula, N.; Manju, G.; Sijikumar, S.; Pant, Tarun; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.018 |
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Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes Geethakumari, Gopika; Aikio, Anita; Cai, Lei; Vanhamaki, Heikki; Pedersen, Marcus; Coster, Anthea; Marchaudon, Aurélie; Blelly, Pierre-Louis; Haberle, Veronika; Maute, Astrid; Ellahouny, Nada; Virtanen, Ilkka; Norberg, Johannes; Soyama, Shin-Ichiro; Grandin, Maxime; Published by: Published on: mar YEAR: 2022 DOI: 10.5194/egusphere-egu22-8194 |
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Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes Geethakumari, Gopika; Aikio, Anita; Cai, Lei; Vanhamaki, Heikki; Pedersen, Marcus; Coster, Anthea; Marchaudon, Aurélie; Blelly, Pierre-Louis; Haberle, Veronika; Maute, Astrid; Ellahouny, Nada; Virtanen, Ilkka; Norberg, Johannes; Soyama, Shin-Ichiro; Grandin, Maxime; Published by: Published on: mar YEAR: 2022 DOI: 10.5194/egusphere-egu22-8194 |
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Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes Geethakumari, Gopika; Aikio, Anita; Cai, Lei; Vanhamaki, Heikki; Pedersen, Marcus; Coster, Anthea; Marchaudon, Aurélie; Blelly, Pierre-Louis; Haberle, Veronika; Maute, Astrid; Ellahouny, Nada; Virtanen, Ilkka; Norberg, Johannes; Soyama, Shin-Ichiro; Grandin, Maxime; Published by: Published on: mar YEAR: 2022 DOI: 10.5194/egusphere-egu22-8194 |
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Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes Geethakumari, Gopika; Aikio, Anita; Cai, Lei; Vanhamaki, Heikki; Pedersen, Marcus; Coster, Anthea; Marchaudon, Aurélie; Blelly, Pierre-Louis; Haberle, Veronika; Maute, Astrid; Ellahouny, Nada; Virtanen, Ilkka; Norberg, Johannes; Soyama, Shin-Ichiro; Grandin, Maxime; Published by: Published on: mar YEAR: 2022 DOI: 10.5194/egusphere-egu22-8194 |
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Total Electron Content Variations during an HSS/CIR driven storm at high and middle latitudes Geethakumari, Gopika; Aikio, Anita; Cai, Lei; Vanhamaki, Heikki; Pedersen, Marcus; Coster, Anthea; Marchaudon, Aurélie; Blelly, Pierre-Louis; Haberle, Veronika; Maute, Astrid; Ellahouny, Nada; Virtanen, Ilkka; Norberg, Johannes; Soyama, Shin-Ichiro; Grandin, Maxime; Published by: Published on: mar YEAR: 2022 DOI: 10.5194/egusphere-egu22-8194 |
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The control of magnetic disturbance induced seed perturbations on the daily variation in night-time ionization irregularity occurrence is studied using ionosonde data and TIMED/GUVI neutral density data at the magnetic equatorial region, Trivandrum. The study reveals that there is a requisite threshold seed amplitude for ESF to occur at a particular altitude and this requisite seed increases as the altitude decreases. This dependence of requisite seed perturbation on altitude for multiple years, which incorporates the electrodynamical effects also, is used as the basis for developing an empirical model to hind-cast ESF. Using the model, the threshold seed perturbation for any day of vernal equinox (ve) season of any year can be delineated if the solar flux index (F10.7) is known. The empirical model is also validated using the data for high and low solar activity periods. The model is able to hind-cast ESF with 92\% success for low solar activity while the success rate for high solar activity is 50\%. Further, the dependence of the threshold curves on neutral density is brought out, thereby confirming the role of ion-neutral coupling processes in modulating the same for magnetically disturbed periods. The geomagnetically disturbed period requisite seed amplitudes are higher than those for quiet periods at a given altitude. This study underlines the importance of disturbance induced seed perturbations and neutral density in controlling ESF occurrence. Published by: Advances in Space Research Published on: mar YEAR: 2022 DOI: 10.1016/j.asr.2021.11.038 Equatorial ionosphere; Equatorial Spread F; Geomagnetically disturbed period; neutral density |
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Far-ultraviolet airglow remote sensing measurements on Feng Yun 3-D meteorological satellite \textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater The Ionospheric Photometer (IPM) is carried on the Feng Yun 3-D (FY3D) meteorological satellite, which allows for the measurement of far-ultraviolet (FUV) airglow radiation in the thermosphere. IPM is a compact and high-sensitivity nadir-viewing FUV remote sensing instrument. It monitors 135.6 nm emission in the nightside thermosphere and 135.6 nm and N\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater Lyman–Birge–Hopfield (LBH) emissions in the dayside thermosphere that can be used to invert the peak electron density of the F\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater layer (NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$)\textless/span\textgreater at night and the \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="73a3f14187048fa14eee70dd1027ad23"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00001.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00001.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater ratio in the daytime, respectively. Preliminary observations show that the IPM could monitor the global structure of the equatorial ionization anomaly (EIA) structure around 02:00 LT using atomic oxygen (OI) 135.6 nm nightglow. It could also identify the reduction of \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7662cd64e23809d534f2b5721e55261b"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00002.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00002.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater in the high-latitude region during the geomagnetic storm of 26 August 2018. The IPM-derived NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater agrees well with that observed by four ionosonde stations along 120\textlessspan class="inline-formula"\textgreater$^\textrm∘$\textless/span\textgreater E with a standard deviation of 26.67 \%. Initial results demonstrate that the performance of IPM meets the design requirements and therefore can be used to study the thermosphere and ionosphere in the future.\textless/p\textgreater Wang, Yungang; Fu, Liping; Jiang, Fang; Hu, Xiuqing; Liu, Chengbao; Zhang, Xiaoxin; Li, JiaWei; Ren, Zhipeng; He, Fei; Sun, Lingfeng; Sun, Ling; Yang, Zhongdong; Zhang, Peng; Wang, Jingsong; Mao, Tian; Published by: Atmospheric Measurement Techniques Published on: mar YEAR: 2022 DOI: 10.5194/amt-15-1577-2022 |
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The ionospheric effects of six intense geomagnetic storms with Dst index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude station, Canberra (45.65° S, 226.30° E), in the Australian Region, by analyzing the storm–time variations in the critical frequency of the F2-region (foF2). Out of six storms, a storm of 23–24 April did not produce any ionospheric effect. The storms of 30 September–3 October (minimum Dst = −122 nT) and 7–10 October (minimum Dst = −109 nT) are presented as case studies and the same analysis was done for the other four storms. The storm of 30 September–3 October, during its main phase, produced a positive ionospheric storm at all three stations with a maximum percentage increase in foF2 (∆foF2\%) of 45.3\% at Canberra whereas during the recovery phase it produced a negative ionospheric storm at all three stations with a maximum ∆foF2\% of −63.5\% at Canberra associated with a decrease in virtual height of the F-layer (h’F). The storm of 7–10 October produced a strong long-duration negative ionospheric storm associated with an increase in h’F during its recovery phase at all three stations with a maximum ∆foF2\% of −65.1\% at Townsville. The negative ionospheric storms with comparatively longer duration were more pronounced in comparison to positive storms and occurred only during the recovery phase of storms. The storm main phase showed positive ionospheric storms for two storms (14–15 July and 30 September–3 October) and other three storms did not produce any ionospheric storm at the low-latitude station indicating prompt penetrating electric fields (PPEFs) associated with these storms did not propagate to the low latitude. The positive ionospheric storms during the main phase are accounted to PPEFs affecting ionospheric equatorial E × B drifts and traveling ionospheric disturbances due to joule heating at the high latitudes. The ionospheric effects during the recovery phase are accounted to the disturbance dynamo electric fields and overshielding electric field affecting E × B drifts and the storm-induced circulation from high latitudes toward low latitudes leading to changes in the natural gas composition [O/N2] ratio. Published by: Atmosphere Published on: mar YEAR: 2022 DOI: 10.3390/atmos13030480 Geomagnetic storms; \textbfE × \textbfB drifts; disturbance dynamo electric fields; prompt penetrating electric fields; storm-induced circulation |
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The ionospheric effects of six intense geomagnetic storms with Dst index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude station, Canberra (45.65° S, 226.30° E), in the Australian Region, by analyzing the storm–time variations in the critical frequency of the F2-region (foF2). Out of six storms, a storm of 23–24 April did not produce any ionospheric effect. The storms of 30 September–3 October (minimum Dst = −122 nT) and 7–10 October (minimum Dst = −109 nT) are presented as case studies and the same analysis was done for the other four storms. The storm of 30 September–3 October, during its main phase, produced a positive ionospheric storm at all three stations with a maximum percentage increase in foF2 (∆foF2\%) of 45.3\% at Canberra whereas during the recovery phase it produced a negative ionospheric storm at all three stations with a maximum ∆foF2\% of −63.5\% at Canberra associated with a decrease in virtual height of the F-layer (h’F). The storm of 7–10 October produced a strong long-duration negative ionospheric storm associated with an increase in h’F during its recovery phase at all three stations with a maximum ∆foF2\% of −65.1\% at Townsville. The negative ionospheric storms with comparatively longer duration were more pronounced in comparison to positive storms and occurred only during the recovery phase of storms. The storm main phase showed positive ionospheric storms for two storms (14–15 July and 30 September–3 October) and other three storms did not produce any ionospheric storm at the low-latitude station indicating prompt penetrating electric fields (PPEFs) associated with these storms did not propagate to the low latitude. The positive ionospheric storms during the main phase are accounted to PPEFs affecting ionospheric equatorial E × B drifts and traveling ionospheric disturbances due to joule heating at the high latitudes. The ionospheric effects during the recovery phase are accounted to the disturbance dynamo electric fields and overshielding electric field affecting E × B drifts and the storm-induced circulation from high latitudes toward low latitudes leading to changes in the natural gas composition [O/N2] ratio. Published by: Atmosphere Published on: mar YEAR: 2022 DOI: 10.3390/atmos13030480 Geomagnetic storms; \textbfE × \textbfB drifts; disturbance dynamo electric fields; prompt penetrating electric fields; storm-induced circulation |
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This study investigates the sequence of solar and interplanetary events that drove the 1 June 2013 and October 2015 geomagnetic storms and how the American (68°–78oE) and African (32°–42oE) Equatorial Ionization Anomaly (EIA) regions responded to them. We constructed the EIA structures by using Total Electron Content (TEC) and ionospheric irregularities derived from Global Navigation Satellite System (GNSS) receivers along with the study locations. We also analyzed disturbed time ionospheric electric field and model data alongside the GNSS data. The 1 June 2013 geomagnetic storm was driven by a combination of a weak CME and HSSs from solar coronal holes, while the 7 October 2015 storm was solely driven by HSSs. Storm-time hemispherical asymmetry in ionospheric TEC and irregularities distributions was consistently observed. Storm with minimum SYM-H value at day-side locations caused enhancement in plasma ionization and pole-ward movement of EIA crests, while storm with minimum SYM-H value at night-side locations caused reduction in plasma ionization and equator-ward movement of EIA crests. The phase of responses of the ionosphere to geomagnetic storms depends on the local time of storm’s onset and local time of the storm’s main phase minimum which also determine the orientation of Prompt Penetration Electric Field (PPEF). At storm’s onset time in the low latitude regions, the main storm-induced electric field is PPEF. Daytime eastward PPEF intensified plasma fountain to increase the EIA crests locations, while nighttime westward PPEF reversed plasma fountain to cause equator-ward collapse of the EIA crests. However, around the storm’s recovery phase, under southward turning of IMF Bz, depending on their orientations, PPEF and Disturbed Dynamo Electric Field (DDEF) collectively influenced low latitude ionosphere. Eastward PPEF at the Pre-Reversal Enhancement (PRE) time enhanced irregularities generation, while westward DDEF at PRE time inhibited irregularities generation. The season of storm’s occurrence is also a factor that dictates ionospheric response to a storm, for instance, the 7 October storm (SYM-H −124 nT) influenced the ionosphere more than the 1 June storm (SYM-H −137 nT). Both storms had long recovery phase. On pre-storm days, we observed stronger and well-developed EIA crests over the American sector than over the African sector. Oyedokun, Oluwole; Amaechi, P.; Akala, A.; Simi, K.; Ogwala, Aghogho; Oyeyemi, E.; Published by: Advances in Space Research Published on: mar YEAR: 2022 DOI: 10.1016/j.asr.2021.12.027 geomagnetic storm; total electron content; Corotating Interacting Region; ionospheric irregularities |
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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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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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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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Contribution of the lower atmosphere to the day-to-day variation of thermospheric density In this paper we carried out a numerical experiment using the Specified Dynamics mode of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (SD-WACCM-X). One SD-WACCM-X run was with realistic Kp and F10.7 and the other with constant Kp and F10.7. By comparing the day-to-day variability of thermosphere mass density at 300 km (low earth orbit, LEO) and 120 km (reentry level) in these two runs, we find that the density variation at 300 km is mainly driven by geomagnetic and solar forcing while at 120 km it is exclusively controlled by the lower atmosphere. At LEO altitudes, during solar minimum and geomagnetic quiet days, the impact from the lower atmosphere is much smaller than the effect of solar and geomagnetic variations but is not negligible (5–10\% vs 20\%). Yue, Jia; Yu, Wandi; Pedatella, Nick; Bruinsma, Sean; Wang, Ningchao; Liu, Huixin; Published by: Advances in Space Research Published on: jun YEAR: 2022 DOI: 10.1016/j.asr.2022.06.011 |
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We present the results of study on the variations of ionospheric total electron content (TEC) by using global, hemispheric, and regional electron contents computed from the global ionospheric maps (GIMs) for the period from 1999 to 2020. For a low and moderate solar activity, the global and regional electron contents vary linearly with solar 10.7 cm radio flux and EUV flux. While a saturation effect in the electron content verses EUV and F10.7 is found during the high solar activity periods at all regions, the maximum effect is observed at low-latitudes followed by high and mid-latitudes region. The extent of saturation effect is more pronounced for F10.7 as compared to EUV. A wavelet transform is applied to global and hemispheric electron contents to examine the relative strength of different variations. The semi-annual variations dominate in the northern hemisphere, whereas annual variations dominate in the southern counterpart. The amplitude of annual variations in southern hemisphere is found to be higher than northern counterpart at all latitudes. This asymmetry in the amplitude of annual variation is maximum at low-latitudes, followed by mid and high-latitudes, respectively. The semi-annual variations are in-phase in both hemisphere and follow the solar cycle. The northern hemisphere depicts relatively large amplitude of semi-annual variations and exhibit the maximum effect at high-latitudes. Younas, Waqar; Amory-Mazaudier, C.; Khan, Majid; Amaechi, Paul; Published by: Advances in Space Research Published on: jul YEAR: 2022 DOI: 10.1016/j.asr.2022.07.029 annual variation; global electron content; Ionosphere; semi-annual variation; total electron content |
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We present the results of study on the variations of ionospheric total electron content (TEC) by using global, hemispheric, and regional electron contents computed from the global ionospheric maps (GIMs) for the period from 1999 to 2020. For a low and moderate solar activity, the global and regional electron contents vary linearly with solar 10.7 cm radio flux and EUV flux. While a saturation effect in the electron content verses EUV and F10.7 is found during the high solar activity periods at all regions, the maximum effect is observed at low-latitudes followed by high and mid-latitudes region. The extent of saturation effect is more pronounced for F10.7 as compared to EUV. A wavelet transform is applied to global and hemispheric electron contents to examine the relative strength of different variations. The semi-annual variations dominate in the northern hemisphere, whereas annual variations dominate in the southern counterpart. The amplitude of annual variations in southern hemisphere is found to be higher than northern counterpart at all latitudes. This asymmetry in the amplitude of annual variation is maximum at low-latitudes, followed by mid and high-latitudes, respectively. The semi-annual variations are in-phase in both hemisphere and follow the solar cycle. The northern hemisphere depicts relatively large amplitude of semi-annual variations and exhibit the maximum effect at high-latitudes. Younas, Waqar; Amory-Mazaudier, C.; Khan, Majid; Amaechi, Paul; Published by: Advances in Space Research Published on: jul YEAR: 2022 DOI: 10.1016/j.asr.2022.07.029 annual variation; global electron content; Ionosphere; semi-annual variation; total electron content |
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We have investigated the global hemispheric differences in thermospheric ∑O/N2 and its impact on the ionospheric total electron content (TEC) at mid- and low-latitudes. Four intense storms of solar cycle 24 (SC-24) have been considered, three of them occurred in Spring equinox and one in Summer solstice season. It is found that the mid-latitudes region has exhibited a large decrease in ∑O/N2 during all the phases of the storms under consideration, which corresponds well to the observed negative storm effects. This decrease is directly related with the storm intensity. The maximum reduction in the ∑O/N2 is observed for the St. Patrick day storm of 2015 (which was the most intense geomagnetic storm of SC-24), whereas the respective minimum decrease is found for the storm of April 2012. Strong hemispheric asymmetries, in ∑O/N2 variation, have been observed at the mid-latitudes sector, and can be associated with the asymmetric energy input as indicated by polar cap (PC) indices. The high speed solar winds streams (HSSWs) during the recovery phases of March 2013 and 2015 storms have caused a significant reduction in ∑O/N2 at mid-latitudes, which could not be reproduced by the coupled thermosphere-ionosphere-plasmasphere electrodynamics (CTIPe) model. On the other hand the low-latitudes region depicts an enhancement in ∑O/N2 during all the storms except for the early recovery phases. The positive storm effect at low-latitudes agrees well with this ∑O/N2 increase, thus indicating that the composition change is one of the major drivers of TEC enhancement at low-latitudes. The CTIPe model showed discrepancies in reproducing the satellite data for all the considered storms, especially during the recovery phases. Furthermore, the model is failed to replicate the hemispheric asymmetries at low and mid-latitudes during the main and early recovery phases. Younas, Waqar; Khan, Majid; Amory-Mazaudier, C.; Amaechi, Paul; Fleury, R.; Published by: Advances in Space Research Published on: jan YEAR: 2022 DOI: 10.1016/j.asr.2021.10.027 CTIPe model; Disturbed ∑O/N; GUVI/TIMED data; Hemispheric asymmetries; REC |
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We have investigated the global hemispheric differences in thermospheric ∑O/N2 and its impact on the ionospheric total electron content (TEC) at mid- and low-latitudes. Four intense storms of solar cycle 24 (SC-24) have been considered, three of them occurred in Spring equinox and one in Summer solstice season. It is found that the mid-latitudes region has exhibited a large decrease in ∑O/N2 during all the phases of the storms under consideration, which corresponds well to the observed negative storm effects. This decrease is directly related with the storm intensity. The maximum reduction in the ∑O/N2 is observed for the St. Patrick day storm of 2015 (which was the most intense geomagnetic storm of SC-24), whereas the respective minimum decrease is found for the storm of April 2012. Strong hemispheric asymmetries, in ∑O/N2 variation, have been observed at the mid-latitudes sector, and can be associated with the asymmetric energy input as indicated by polar cap (PC) indices. The high speed solar winds streams (HSSWs) during the recovery phases of March 2013 and 2015 storms have caused a significant reduction in ∑O/N2 at mid-latitudes, which could not be reproduced by the coupled thermosphere-ionosphere-plasmasphere electrodynamics (CTIPe) model. On the other hand the low-latitudes region depicts an enhancement in ∑O/N2 during all the storms except for the early recovery phases. The positive storm effect at low-latitudes agrees well with this ∑O/N2 increase, thus indicating that the composition change is one of the major drivers of TEC enhancement at low-latitudes. The CTIPe model showed discrepancies in reproducing the satellite data for all the considered storms, especially during the recovery phases. Furthermore, the model is failed to replicate the hemispheric asymmetries at low and mid-latitudes during the main and early recovery phases. Younas, Waqar; Khan, Majid; Amory-Mazaudier, C.; Amaechi, Paul; Fleury, R.; Published by: Advances in Space Research Published on: jan YEAR: 2022 DOI: 10.1016/j.asr.2021.10.027 CTIPe model; Disturbed ∑O/N; GUVI/TIMED data; Hemispheric asymmetries; REC |
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This paper studies the response of the ionospheric parameters critical frequency (foF2), their height (hmF2), and Total Electron Content (TEC) at mid, low, and near-equatorial latitudes of the South American sector during the intense geomagnetic storm of 26 August 2018. The ionospheric response at the beginning of the main phase was different depending on latitude (in general, there were decreases in foF2 at near-equatorial and low latitudes and small increases at mid-latitudes). During the recovery, positive storm effects in foF2 and TEC were observed almost all day on 26 August 2018 overall the stations along all the latitudes and also on 27 August. The initial effects were possibly caused by a weak prompt penetration electric field while the enhanced ratio of thermosphere neutral composition i.e. [O]/[N2] was considered as the main cause for the positive storm effects during the recovery phase. Mansilla, Gustavo; Zossi, Marta; Published by: Advances in Space Research Published on: jan YEAR: 2022 DOI: 10.1016/j.asr.2021.08.002 |
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Scintillation due to ionospheric plasma irregularities remains a challenging task for the space science community as it can severely threaten the dynamic systems relying on space-based navigation services. In the present paper, we probe the ionospheric current and plasma irregularity characteristics from a latitudinal arrangement of magnetometers and Global Navigation Satellite System (GNSS) stations from the equator to the far low latitude location over the Indian longitudes, during the severe space weather events of 6–10 September 2017 that are associated with the strongest and consecutive solar flares in the 24th solar cycle. The night-time influence of partial ring current signatures in ASYH and the daytime influence of the disturbances in the ionospheric E region electric currents (Diono) are highlighted during the event. The total electron content (TEC) from the latitudinal GNSS observables indicate a perturbed equatorial ionization anomaly (EIA) condition on 7 September, due to a sequence of M-class solar flares and associated prompt penetration electric fields (PPEFs), whereas the suppressed EIA on 8 September with an inverted equatorial electrojet (EEJ) suggests the driving disturbance dynamo electric current (Ddyn) corresponding to disturbance dynamo electric fields (DDEFs) penetration in the E region and additional contributions from the plausible storm-time compositional changes (O/N2) in the F-region. The concurrent analysis of the Diono and EEJ strengths help in identifying the pre-reversal effect (PRE) condition to seed the development of equatorial plasma bubbles (EPBs) during the local evening sector on the storm day. The severity of ionospheric irregularities at different latitudes is revealed from the occurrence rate of the rate of change of TEC index (ROTI) variations. Further, the investigations of the hourly maximum absolute error (MAE) and root mean square error (RMSE) of ROTI from the reference quiet days’ levels and the timestamps of ROTI peak magnitudes substantiate the severity, latitudinal time lag in the peak of irregularity, and poleward expansion of EPBs and associated scintillations. The key findings from this study strengthen the understanding of evolution and the drifting characteristics of plasma irregularities over the Indian low latitudes. Vankadara, Ram; Panda, Sampad; Amory-Mazaudier, Christine; Fleury, Rolland; Devanaboyina, Venkata; Pant, Tarun; Jamjareegulgarn, Punyawi; Haq, Mohd; Okoh, Daniel; Seemala, Gopi; Published by: Remote Sensing Published on: jan YEAR: 2022 DOI: 10.3390/rs14030652 space weather; equatorial plasma bubbles; ionospheric irregularity; global navigation satellite system; magnetometer; poleward drift; rate of change of TEC index; scintillations; storm-time electric currents |
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Scintillation due to ionospheric plasma irregularities remains a challenging task for the space science community as it can severely threaten the dynamic systems relying on space-based navigation services. In the present paper, we probe the ionospheric current and plasma irregularity characteristics from a latitudinal arrangement of magnetometers and Global Navigation Satellite System (GNSS) stations from the equator to the far low latitude location over the Indian longitudes, during the severe space weather events of 6–10 September 2017 that are associated with the strongest and consecutive solar flares in the 24th solar cycle. The night-time influence of partial ring current signatures in ASYH and the daytime influence of the disturbances in the ionospheric E region electric currents (Diono) are highlighted during the event. The total electron content (TEC) from the latitudinal GNSS observables indicate a perturbed equatorial ionization anomaly (EIA) condition on 7 September, due to a sequence of M-class solar flares and associated prompt penetration electric fields (PPEFs), whereas the suppressed EIA on 8 September with an inverted equatorial electrojet (EEJ) suggests the driving disturbance dynamo electric current (Ddyn) corresponding to disturbance dynamo electric fields (DDEFs) penetration in the E region and additional contributions from the plausible storm-time compositional changes (O/N2) in the F-region. The concurrent analysis of the Diono and EEJ strengths help in identifying the pre-reversal effect (PRE) condition to seed the development of equatorial plasma bubbles (EPBs) during the local evening sector on the storm day. The severity of ionospheric irregularities at different latitudes is revealed from the occurrence rate of the rate of change of TEC index (ROTI) variations. Further, the investigations of the hourly maximum absolute error (MAE) and root mean square error (RMSE) of ROTI from the reference quiet days’ levels and the timestamps of ROTI peak magnitudes substantiate the severity, latitudinal time lag in the peak of irregularity, and poleward expansion of EPBs and associated scintillations. The key findings from this study strengthen the understanding of evolution and the drifting characteristics of plasma irregularities over the Indian low latitudes. Vankadara, Ram; Panda, Sampad; Amory-Mazaudier, Christine; Fleury, Rolland; Devanaboyina, Venkata; Pant, Tarun; Jamjareegulgarn, Punyawi; Haq, Mohd; Okoh, Daniel; Seemala, Gopi; Published by: Remote Sensing Published on: jan YEAR: 2022 DOI: 10.3390/rs14030652 space weather; equatorial plasma bubbles; ionospheric irregularity; global navigation satellite system; magnetometer; poleward drift; rate of change of TEC index; scintillations; storm-time electric currents |
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Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from the Abel transform integral are useful for implementing remote sensing data analysis methods, such as the numerical inverse Abel transform. We propose analytical expressions obtained by a suitable, non-alternating, series development to compute those indefinite integrals. We establish expressions allowing absolute accuracy control of the convergence of these series and illustrate how this accuracy depends on the number of terms involved in the series computation. We compare the analytical method with numerical computation techniques, which are found to be sufficiently accurate as well. Inverse Abel transform fitting is then tested in order to establish that the expected emission rate profiles can be retrieved from the observation of both planetary and cometary atmospheres. We show that the method is robust, i.e. that it can be applied even when the properties of the observed atmosphere depart from the assumed ones, especially when Tikhonov regularization is included. A first application is conducted over observation of comet 46P/Wirtanen, showing some variability, possibly attributable to an evolution of the contamination by dust and icy grains. Hubert, B.; Munhoven, G.; Moulane, Y.; Hutsemekers, D.; Manfroid, J.; Opitom, C.; Jehin, E.; Published by: Icarus Published on: jan YEAR: 2022 DOI: 10.1016/j.icarus.2021.114654 Abel transform; Aeronomy; Coma; Cometary atmospheres; Comets; Data reduction techniques; Planetary atmospheres. |
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Ionospheric response of St. Patrick’s Day geomagnetic storm over Indian low latitude regions The current work shows the ionospheric response to an intense geomagnetic storm known as St. Patrick’s Day storm which occurred from 17-22 March 2015 using the ionospheric Chaurasiya, Sunil; Patel, Kalpana; Kumar, Sanjay; Singh, Abhay; Published by: Astrophysics and Space Science Published on: YEAR: 2022 DOI: 10.1007/s10509-022-04137-3 |
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We present the ionospheric response of geomagnetic storms as observed from ionospheric Total Electron Content (TEC). We select nine storm events and study the GPS-TEC profiles Kundu, Subrata; Sasmal, Sudipta; Published by: Published on: YEAR: 2022 DOI: 10.21203/rs.3.rs-1652015/v1 |
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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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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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The 15 January 2022 Hunga Tonga Eruption History as Inferred From Ionospheric Observations On 15 January 2022, the Hunga Tonga-Hunga Ha’apai submarine volcano erupted violently and triggered a giant atmospheric shock wave and tsunami. The exact mechanism of this extraordinary eruptive event, its size and magnitude are not well understood yet. In this work, we analyze data from the nearest ground-based receivers of Global Navigation Satellite System to explore the ionospheric total electron content (TEC) response to this event. We show that the ionospheric response consists of a giant TEC increase followed by a strong long-lasting depletion. We observe that the explosive event of 15 January 2022 began at 04:05:54UT and consisted of at least five explosions. Based on the ionospheric TEC data, we estimate the energy released during the main major explosion to be between 9 and 37 Megatons in trinitrotoluene equivalent. This is the first detailed analysis of the eruption sequence scenario and the timeline from ionospheric TEC observations. Astafyeva, E.; Maletckii, B.; Mikesell, T.; Munaibari, E.; Ravanelli, M.; Coisson, P.; Manta, F.; Rolland, L.; Published by: Geophysical Research Letters Published on: YEAR: 2022 DOI: 10.1029/2022GL098827 co-volcanic ionospheric disturbances; eruption timeline; GNSS; Hunga Tonga eruption; Ionosphere; ionospheric geodesy |
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The 15 January 2022 Hunga Tonga Eruption History as Inferred From Ionospheric Observations On 15 January 2022, the Hunga Tonga-Hunga Ha’apai submarine volcano erupted violently and triggered a giant atmospheric shock wave and tsunami. The exact mechanism of this extraordinary eruptive event, its size and magnitude are not well understood yet. In this work, we analyze data from the nearest ground-based receivers of Global Navigation Satellite System to explore the ionospheric total electron content (TEC) response to this event. We show that the ionospheric response consists of a giant TEC increase followed by a strong long-lasting depletion. We observe that the explosive event of 15 January 2022 began at 04:05:54UT and consisted of at least five explosions. Based on the ionospheric TEC data, we estimate the energy released during the main major explosion to be between 9 and 37 Megatons in trinitrotoluene equivalent. This is the first detailed analysis of the eruption sequence scenario and the timeline from ionospheric TEC observations. Astafyeva, E.; Maletckii, B.; Mikesell, T.; Munaibari, E.; Ravanelli, M.; Coisson, P.; Manta, F.; Rolland, L.; Published by: Geophysical Research Letters Published on: YEAR: 2022 DOI: 10.1029/2022GL098827 co-volcanic ionospheric disturbances; eruption timeline; GNSS; Hunga Tonga eruption; Ionosphere; ionospheric geodesy |
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Disappearance of the Polar Cap Ionosphere During Geomagnetic Storm on 11 May 2019 Multi-instrument data from Jang Bogo Station (JBS) in Antarctica were utilized to study ionospheric responses to the 11 May 2019 moderate geomagnetic storm. These include Vertical Incident Pulsed Ionospheric Radar (VIPIR)/Dynasonde, Fabry-Perot Interferometer (FPI), GPS vertical total electron content (vTEC), and magnetometer. The VIPIR/Dynasonde observed long-lasting (\textgreater11 hr) severe depletion of the electron density in the F-region ionosphere over JBS. During the depletion interval, GPS TEC also correspondingly decreased, FPI neutral temperature was significantly enhanced, and the polar magnetic field variations showed positive and negative excursions in the Y (east) and Z (vertical) components, respectively. GK-2 A satellite, located ∼2.5 hr west of JBS, observed negative magnetic field perturbations in the azimuthal BD component at geosynchronous orbit during the depletion of ionospheric plasma. Such a BD perturbation at geosynchronous orbit is due to the field-aligned currents flowing out of the ionosphere. From these observations we suggest that transpolar ionospheric currents connected to the field-aligned currents flowing on a substorm wedge-shaped circuit act as a source of polar atmospheric heating during the moderate geomagnetic storm interval and that elevated heavy molecular gases (O2 and N2) by atmospheric heating contribute to the electron density depletion via increased recombination rate. Kwon, H.-J.; Kim, K.-H.; Jee, G.; Seon, J.; Lee, C.; Ham, Y.-B.; Hong, J.; Kim, E.; Bullett, T.; Auster, H.-U.; Magnes, W.; Kraft, S.; Published by: Space Weather Published on: YEAR: 2022 DOI: 10.1029/2022SW003054 |
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The latitudinal and temporal variation of atomic oxygen (O) is opposite between the empirical model, NRLMSISE-00 (MSIS) and the whole atmosphere model, whole atmosphere community climate model with thermosphere and ionosphere extension (WACCM-X) at 97–100 km. Atomic Oxygen from WACCM-X has maxima at solstices and summer mid-high latitudes, similar to [O] from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). We use the densities and dynamics from WACCM-X to drive the Global Ionosphere Thermosphere Model (GITM) at its lower boundary and compare it with the MSIS driven GITM. We focus on the differences in the modeling of the thermospheric and ionospheric semiannual oscillation (T-I SAO). Our results reveal that driving GITM with WACCM-X causes the T-I SAO to maximize around solstices, opposite to when MSIS is used. This is because the global mixing in GITM during solstices is not strong enough to decrease the solstitial [O] densities below the equinoctial values between mesosphere and lower thermosphere (MLT) and upper thermosphere. Larger summer [O] in the MLT leads to the accumulation of [O] at lower latitudes in the thermosphere due to weaker meridional transport, which further increases the amplitude of the oppositely phased SAO. WACCM-X itself has the right phase of SAO in the upper thermosphere but wrong at lower altitudes. The exact mechanisms that can correct the phase of T-I SAO in GITM while using SABER-like [O] in the MLT are currently unknown and warrant further investigation. We suggest mechanisms that can reduce the solstitial maxima in the lower thermosphere, for example, stronger interhemispheric meridional winds, stronger residual circulation, seasonal variations in eddy diffusion, and momentum from breaking gravity waves. Malhotra, Garima; Ridley, Aaron; , Jones; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029320 global ionosphere thermosphere modeling; semiannual oscillation; thermospheric and ionospheric SAO; thermospheric spoon mechanism; vertical coupling of thermosphere with lower atmosphere; whole atmosphere community climate model with thermosphere and ionosphere extension (WACCM-X) |
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Far ultraviolet (FUV) imaging of the aurora from space provides great insight into the dynamic coupling of the atmosphere, ionosphere, and magnetosphere on global scales. To gain a quantitative understanding of these coupling processes, the global distribution of auroral energy flux is required, but the inversion of FUV emission to derive precipitating auroral particles energy flux is not straightforward. Furthermore, the spatial coverage of FUV imaging from Low Earth Orbit (LEO) altitudes is often insufficient to achieve global mapping of this important parameter. This study seeks to fill these gaps left by the current geospace observing system using a combination of data assimilation and machine learning techniques. Specifically, this paper presents a new data-driven modeling approach to create instantaneous, global assimilative mappings of auroral electron total energy flux from Lyman-Birge-Hopfield (LBH) emission data from the Defense Meteorological System Program (DMSP) Special Sensor Ultraviolet Spectrographic Imager (SSUSI). We take a two-step approach; the creation of assimilative maps of LBH emission using optimal interpolation, followed by the conversion to energy flux using a neural network model trained with conjunction observations of in-situ auroral particles and LBH emission from the DMSP Special Sensor J and SSUSI instruments. The paper demonstrates the feasibility of this approach with a model prototype built with DMSP data from 17 February 2014 to 23 February 2014. This study serves as a blueprint for a future comprehensive data-driven model of auroral energy flux that is complementary to traditional inversion techniques to take advantage of FUV imaging from LEO platforms for global assimilative mapping of auroral energy flux. Li, J.; Matsuo, T.; Kilcommons, L.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029739 |
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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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The Terrestrial Magnetospheric Response to the 28th October 2021 CME Waters, James; Jackman, Caitriona; Whiter, Daniel; Fogg, Alexandra; Lamy, Laurent; Carter, Jennifer; Fryer, Laura; Louis, Corentin; Carley, Eion; Briand, Carine; , others; Published by: Published on: |
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We use the in-situ observations of DMSP and SWARM satellites to report the changes of the topside ionospheric electron temperature during the October 2016 storm. Electron temperature in the afternoon sector dramatically increases in low latitudes in the recovery phase of the storm. Furthermore, the temperature enhancements have an obvious dependence on longitude and are mainly centralized around 100°–150°E in different satellite observations. The temperature enhancements attain more than 2,000 K at 840 km and 1,500 K at 450 km around the magnetic equator. The decrease in the electron-ion collision cooling rate, resulting from the lessened topside electron density, could not fully explain the temperature enhancement. At the same time, the electron densities in crests of the equatorial ionization anomaly are suppressed drastically at 100°–150°E, which cause a less heat conduction effect from the equatorial topside ionosphere to low altitudes via magnetic field lines and heat the topside ionospheric electron temperature. Further analysis indicates that dayside westward disturbance dynamo electric field presents a significant longitude structure and is a primary driver for the topside ionospheric temperature enhancement during the storm. Zhang, Ruilong; Liu, Libo; Ma, Han; Chen, Yiding; Le, Huijun; Yoshikawa, Akimasa; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2022JA030278 electron temperature; equatorial topisde; Ionospheric storm; vertical drift |
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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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This study presents multi-instrument observations of persistent large-scale traveling ionosphere/atmospheric disturbances (LSTIDs/LSTADs) observed during moderately increased auroral electrojet activity and a sudden stratospheric warming in the polar winter hemisphere. The Global Ultraviolet Imager (GUVI), Gravity field and steady-state Ocean Circulation Explorer, Scanning Doppler Imaging Fabry–Perot Interferometers, and the Poker Flat Incoherent Scatter Radar are used to demonstrate the presence of LSTIDs/LSTADs between 19 UT and 5 UT on 18–19 January 2013 over the Alaska region down to lower midlatitudes. This study showcases the first use of GUVI for the study of LSTADs. These novel GUVI observations demonstrate the potential for the GUVI far ultraviolet emissions to be used for global-scale studies of waves and atmospheric disturbances in the thermosphere, a region lacking in long-term global measurements. These observations typify changes in the radiance from around 140 to 180 km, opening a new window into the behavior of the thermosphere. Bossert, Katrina; Paxton, Larry; Matsuo, Tomoko; Goncharenko, Larisa; Kumari, Komal; Conde, Mark; Published by: Geophysical Research Letters Published on: YEAR: 2022 DOI: 10.1029/2022GL099901 |
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This study presents multi-instrument observations of persistent large-scale traveling ionosphere/atmospheric disturbances (LSTIDs/LSTADs) observed during moderately increased auroral electrojet activity and a sudden stratospheric warming in the polar winter hemisphere. The Global Ultraviolet Imager (GUVI), Gravity field and steady-state Ocean Circulation Explorer, Scanning Doppler Imaging Fabry–Perot Interferometers, and the Poker Flat Incoherent Scatter Radar are used to demonstrate the presence of LSTIDs/LSTADs between 19 UT and 5 UT on 18–19 January 2013 over the Alaska region down to lower midlatitudes. This study showcases the first use of GUVI for the study of LSTADs. These novel GUVI observations demonstrate the potential for the GUVI far ultraviolet emissions to be used for global-scale studies of waves and atmospheric disturbances in the thermosphere, a region lacking in long-term global measurements. These observations typify changes in the radiance from around 140 to 180 km, opening a new window into the behavior of the thermosphere. Bossert, Katrina; Paxton, Larry; Matsuo, Tomoko; Goncharenko, Larisa; Kumari, Komal; Conde, Mark; Published by: Geophysical Research Letters Published on: YEAR: 2022 DOI: 10.1029/2022GL099901 |
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Nitric Oxide is a very important trace species which plays a significant role acting as a natural thermostat in Earth’s thermosphere during strong geomagnetic activity. In this paper, we present various aspects related to the variation in the NO Infrared radiative flux (IRF) exiting the thermosphere by utilizing the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/ Sounding of the Atmosphere using Broadband Emission Radiometry) observational data during the Halloween storm which occurred in late October 2003. The Halloween storm comprised of three intense-geomagnetic storms. The variability of NO infrared flux during these storm events and its connection to the strength of the geomagnetic storms were found to be different in contrast to similar super storms. Ranjan, Alok; Krishna, MV; Kumar, Akash; Sarkhel, Sumanta; Bharti, Gaurav; Bender, Stefan; Sinnhuber, Miriam; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2022.07.035 |
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Climatology of O/N2 Variations at Low-and Mid-Latitudes during Solar Cycles 23 and 24 We present a study concerning the thermospheric O/N2 variations for the period 2002 to 2020, using the measurements of global ultraviolet imager (GUVI) onboard TIMED satellite. In this regard, monthly averaged O/N2 was computed—using the five quietest days of the month—at low- and mid-latitudes. To find the longitudinal dependence of thermospheric variations, the analysis is further extended to different longitudinal sectors, namely Asia, Africa, and America. We found that the latitudinal and longitudinal O/N2 variations follow the solar activity. These variations, during a high solar activity in northern winter, are found to be always much greater than southern winter and northern summer. The latitudinal and longitudinal variations of O/N2 at low- and mid-latitudes in December solstice are observed to be higher than June solstice counterparts in the northern hemisphere. We also computed the amplitudes of annual and semiannual variations using the bandpass filters. The former variations of O/N2 for low-latitudes do not follow the solar activity in the southern hemisphere. Moreover, these variations are stronger for mid-latitudes as compared with low-latitude regions. Similarly, the annual variations in Asian and African sectors of southern hemisphere do not follow the solar cycle (SC) trends. Khan, Jahanzeb; Younas, Waqar; Khan, Majid; Amory-Mazaudier, Christine; Published by: Atmosphere Published on: YEAR: 2022 DOI: 10.3390/atmos13101645 |
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This study presents ionospheric responses of the mid and low-latitude region in the Europe-African longitude sector (along 30 +/- 10 deg E) to the intense geomagnetic storm of 23–31 August 2018 (SYM-Hmin = −207 nT) using the Global Ionospheric Map (GIM) and Global Positioning System (GPS) receivers data, the satellite data (SWARM, Defense Meteorological Satellite Program (DMSP), Global Ultraviolet Imager on board the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (GUVI/TIMED)), and Prompt Penetration Equatorial Electric Field model (PPEFM). The percentage deviation in total electron content (TEC) denoted by TEC () was used to observe the ionospheric storm effects. Dugassa, Teshome; Mezgebe, Nigussie; Habarulema, John; Habyarimana, Valence; Oljira, Asebe; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2022.10.063 |
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This study presents ionospheric responses of the mid and low-latitude region in the Europe-African longitude sector (along 30 +/- 10 deg E) to the intense geomagnetic storm of 23–31 August 2018 (SYM-Hmin = −207 nT) using the Global Ionospheric Map (GIM) and Global Positioning System (GPS) receivers data, the satellite data (SWARM, Defense Meteorological Satellite Program (DMSP), Global Ultraviolet Imager on board the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (GUVI/TIMED)), and Prompt Penetration Equatorial Electric Field model (PPEFM). The percentage deviation in total electron content (TEC) denoted by TEC () was used to observe the ionospheric storm effects. Dugassa, Teshome; Mezgebe, Nigussie; Habarulema, John; Habyarimana, Valence; Oljira, Asebe; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2022.10.063 |
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The thermospheric O/N2 ratio obtained from the TIMED/GUVI instrument for TIMED/GUVI observations of the O/N The authors ack nowledge the Global Ultraviolet Imager (GUVI) for the Reznychenko, M; Bogomaz, O; Kotov, D; Zhivolup, T; Koloskov, O; , Lisachenko; Published by: Ukrainian Antarctic Journal Published on: YEAR: 2022 DOI: 10.33275/1727-7485.1.2022.686 |
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In this article, we analyze vertical total electron content (VTEC) over Nepal for 4 periods: March 14–25, 2015, June 18–29, 2015, May 24–June 4, 2017, and September 3–14, 2017. In each period, there are quiet geomagnetic days and intense geomagnetic stormy days. The VTEC observed during these periods has observed both positive and negative ionospheric storms. We compared VTEC Receiver-Independent Exchange Format (RINEX) observations with the Global Ionospheric Map (GIM), Centre for Orbit Determination in Europe (CODE), and IGS working group (IGSG). We found in RINEX observation of the VTEC a noon bite out profile with predominance of morning and afternoon peaks and a nighttime peak, but this was not noticeable clearly with CODE and IGSG models. The comparison between RINEX TEC, CODE, and IGSG models shows that the GIM model does not estimate RINEX VTEC over Nepal. The disagreement between VTEC CODE/IGSG and VTEC RINEX is important during geomagnetically quiet periods, while there is good agreement between VTEC CODE/IGSG and VTEC RINEX during strong geomagnetic storms. We also find a greater disagreement between the models and the data at the equinoxes when the VTEC is larger. It is, therefore, necessary to introduce data from Nepal stations into the models CODE and IGSG in order to improve them Pandit, D; Amory-Mazaudier, Christine; Fleury, R; Chapagain, NP; Adhikari, B; Published by: Indian Journal of Physics Published on: YEAR: 2022 DOI: 10.1007/s12648-022-02441-w |
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We have investigated the global hemispheric differences in thermospheric ∑O/N2 and its impact on the ionospheric total electron content (TEC) at mid- and low-latitudes. Four intense storms of solar cycle 24 (SC-24) have been considered, three of them occurred in Spring equinox and one in Summer solstice season. Younas, Waqar; Khan, Majid; Amory-Mazaudier, C; Amaechi, Paul; Fleury, R; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2021.10.027 |
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We have investigated the global hemispheric differences in thermospheric ∑O/N2 and its impact on the ionospheric total electron content (TEC) at mid- and low-latitudes. Four intense storms of solar cycle 24 (SC-24) have been considered, three of them occurred in Spring equinox and one in Summer solstice season. Younas, Waqar; Khan, Majid; Amory-Mazaudier, C; Amaechi, Paul; Fleury, R; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2021.10.027 |