Bibliography
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Found 77 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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We propose a new method for retrieving the atmospheric number density profile in the lower thermosphere, based on the X-ray Earth occultation of the Crab Nebula with the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite. The absorption and scattering of X-rays by the atmosphere result in changes in the X-ray energy, and the Earth’s neutral atmospheric number density can be directly retrieved by fitting the observed spectrum and spectrum model at different altitude ranges during the occultation process. The pointing observations from LE/Insight-HXMT on 16 November 2017 are analyzed to obtain high-level data products such as lightcurve, energy spectrum and detector response matrix. The results show that the retrieved results based on the spectrum fitting in the altitude range of 90–200 km are significantly lower than the atmospheric density obtained by the NRLMSISE-00 model, especially in the altitude range of 110–120 km, where the retrieved results are 34.4\% lower than the model values. The atmospheric density retrieved by the new method is qualitatively consistent with previous independent X-ray occultation results (Determan et al., 2007; Katsuda et al., 2021), which are also lower than empirical model predictions. In addition, the accuracy of atmospheric density retrieved results decreases with the increase of altitude in the altitude range of 150–200 km, and the accurate quantitative description will be further analyzed after analyzing a large number of X-ray occultation data in the future. Yu, Daochun; Li, Haitao; Li, Baoquan; Ge, Mingyu; Tuo, Youli; Li, Xiaobo; Xue, Wangchen; Liu, Yaning; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.030 Atmospheric density vertical profile; Energy spectrum fitting; X-ray occultation |
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\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater X-ray Earth occultation sounding (XEOS) is an emerging method for measuring the neutral density in the lower thermosphere. In this paper, the X-ray Earth occultation (XEO) of the Crab Nebula is investigated using the Hard X-ray Modulation Telescope (Insight-HXMT). The pointing observation data on the 30 September 2018 recorded by the low-energy X-ray telescope (LE) of Insight-HXMT are selected and analysed. The extinction light curves and spectra during the X-ray Earth occultation process are extracted. A forward model for the XEO light curve is established, and the theoretical observational signal for light curve is predicted. The atmospheric density model is built with a scale factor to the commonly used Mass Spectrometer Incoherent Scatter Radar Extended model (MSIS) density profile within a certain altitude range. A Bayesian data analysis method is developed for the XEO light curve modelling and the atmospheric density retrieval. The posterior probability distribution of the model parameters is derived through the Markov chain–Monte Carlo (MCMC) algorithm with the NRLMSISE-00 model and the NRLMSIS 2.0 model as basis functions, and the respective best-fit density profiles are retrieved. It is found that in the altitude range of 105–200 km, the retrieved density profile is 88.8 \% of the density of NRLMSISE-00 and 109.7 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 1.0–2.5 keV based on the XEOS method. In the altitude range of 95–125 km, the retrieved density profile is 81.0 \% of the density of NRLMSISE-00 and 92.3 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 2.5–6.0 keV based on the XEOS method. In the altitude range of 85–110 km, the retrieved density profile is 87.7 \% of the density of NRLMSISE-00 and 101.4 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 6.0–10.0 keV based on the XEOS method. Goodness-of-fit testing is carried out for the validation of the results. The measurements of density profiles are compared to the NRLMSISE-00 and NRLMSIS 2.0 model simulations and the previous retrieval results with NASA s Rossi X-ray Timing Explorer (RXTE) satellite. For further confirmation, we also compare the measured density profile to the ones by a standard spectrum retrieval method with an iterative inversion technique. Finally, we find that the retrieved density profile from Insight-HXMT based on the NRLMSISE-00 and NRLMSIS 2.0 models is qualitatively consistent with the previous retrieved results from RXTE. The results of light curve fitting and standard energy spectrum fitting are in good agreement. This research provides a method for the evaluation of the density profiles from MSIS model predictions. This study demonstrates that the XEOS from the X-ray astronomical satellite Insight-HXMT can provide an approach for the study of the upper atmosphere. The Insight-HXMT satellite can join the family of the XEOS. The Insight-HXMT satellite with other X-ray astronomical satellites in orbit can form a space observation network for XEOS in the future.\textless/p\textgreater Yu, Daochun; Li, Haitao; Li, Baoquan; Ge, Mingyu; Tuo, Youli; Li, Xiaobo; Xue, Wangchen; Liu, Yaning; Wang, Aoying; Zhu, Yajun; Luo, Bingxian; Published by: Atmospheric Measurement Techniques Published on: may YEAR: 2022 DOI: 10.5194/amt-15-3141-2022 |
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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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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 |
| 2021 |
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The Global Positioning System (GPS) cycle slip has a marked impact on the application of communication and navigation systems and therefore is one of the main concerns of the user and designer of terminal systems. In this study, we analyzed the temporal and spatial characteristics of cycle slip events using the GPS data detected from 260 observations in the China sector during the period of the year 2015–2018. The results show that the temporal variations of cycle slips are dependent on the local time, seasons, and solar activity. It occurs from 20:00 LT to midnight and more frequently in the equinox months, especially in solar maximum years. The spatial distribution occurs mainly at southern sector below 25°N, which should be associated with the solar condition and ionospheric irregularities in the equatorial region, and the case analyses reveal that the variation of cycle slips has a similar tendency with the ionospheric scintillation monitored at low-latitude station Guangzhou explaining this relationship. Our results reflect the performance of the GPS signals monitored in the China area during the declining period of solar activity to some degree. Geng, Wei; Huang, Wengeng; Liu, Guoqi; Liu, Siqing; Luo, Binxian; Chen, Yanhong; Published by: Radio Science Published on: may YEAR: 2021 DOI: 10.1029/2020RS007196 Monitoring; Delays; Global positioning system; Indexes; Receivers; Satellite broadcasting; Signal to noise ratio |
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The changes in the ionosphere during geomagnetic disturbances is one of the prominent Space Weather effects on the near-Earth environment. The character of these changes can differ significantly at different regions on the Earth. We studied ionospheric response to five geomagnetic storms of March 2012, using data of Total Electron Content (TEC) and F2-layer critical frequency (foF2) along the meridian of 70° W in the Northern Hemisphere. There are few ionosondes along this longitudinal sector: in Thule, Sondrestrom, Millstone Hill and Puerto Rico. The lacking foF2 values between the ionosondes were determined by using the experimental latitudinal dependences of the equivalent ionospheric slab thickness and TEC values. During geomagnetic storms, the following features were characteristic: (a) two-hours (or longer in one case) delay of the ionospheric response to disturbances, (b) the more prominent mid-latitude trough and (c) the sharper border of the EIA northern crest. During four storms of 7–17 March, the general tendency was the transition from negative disturbances at high latitudes to intense positive disturbances at low latitudes. During the fifth storm, the negative ionospheric disturbance controlled by O/N2 change was masked by the overall prolonged electron density increase during 21–31 March. The multiple correlation analysis revealed the latitudinal dependence of dominant Space Weather parameters’ impacts on foF2. Sergeeva, Maria; Maltseva, Olga; Caraballo, Ramon; Gonzalez-Esparza, Juan; Corona-Romero, Pedro; Published by: Atmosphere Published on: feb YEAR: 2021 DOI: 10.3390/atmos12020164 foF2; geomagnetic storm; Ionospheric disturbance; ionospheric equivalent slab thickness; statistical analysis; TEC |
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Transpolar Arcs During a Prolonged Radial Interplanetary Magnetic Field Interval Transpolar arcs (TPAs) are believed to predominantly occur under northward interplanetary magnetic field (IMF) conditions with their hemispheric asymmetry controlled by the Sun-Earth (radial) component of the IMF. In this study, we present observations of TPAs that appear in both the northern and southern hemispheres even during a prolonged interval of radially oriented IMF. The Defense Meteorological Satellite Program (DMSP) F16 and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellites observed TPAs on the dawnside polar cap in both hemispheres (one TPA structure in the southern hemisphere and two in the northern hemisphere) during an interval of nearly earthward-oriented IMF on October 29, 2005. The southern hemisphere TPA and one of the northern hemisphere TPAs are associated with electron and ion precipitation and mostly sunward plasma flow (with shears) relative to their surroundings. Meanwhile, the other TPA in the northern hemisphere is associated with an electron-only precipitation and antisunward flow relative to its surroundings. Our observations indicate the following: (a) the TPA formation is not limited to northward IMF conditions; (b) the TPAs can be located on both closed field lines rooted in the polar cap of both hemispheres and open field lines connected to the northward field lines draped over one hemisphere of the magnetopause. We believe that the TPAs presented here are the result of both indirect and direct processes of solar wind energy transfer to the high-latitude ionosphere. Park, Jong-Sun; Shi, Quan; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiu-Gang; Degeling, Alexander; Tian, An; Pitkänen, Timo; Zhang, Yongliang; Rae, Jonathan; Hairston, Marc; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029197 radial IMF; solar wind-magnetosphere-ionosphere coupling; transpolar arc |
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Investigating Geocoronal Absorption for Wavelength Calibration of Sounding Rockets Donders, Nicolas; Winebarger, Amy; Kankelborg, Charles; Vigil, Genevieve; Paxton, Larry; Zank, Gary; Published by: Published on: |
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We describe a long-term data set of global average thermospheric mass density derived from orbit data on ∼7,700 objects in low Earth orbit, via the effect of atmospheric drag. The data cover the years 1967–2019 and altitudes 250–575 km, and the temporal resolution is 3–4 days for most years. The data set is an extension and revision of a previous version. The most important change is the use of more precise orbit data: special perturbation state vectors are now used starting in 2001, instead of mean Keplerian orbital elements. The data are suitable for climatological studies of thermospheric variations and trends, and for space weather studies on time scales longer than 3 days. Emmert, J.; Dhadly, M.; Segerman, A.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029455 |
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Development of a NIR camera for the BALBOA mission More than 500 years ago, when Vasco Núñez de Balboa traveled to the New World, he must not have realized that his legacy would not only be cast in currency, but branded for space Zhou, Xiaoyan; Rafol, Don; Michell, Robert; Hampton, Don; Geach, Christopher; Published by: 43rd COSPAR Scientific Assembly. Held 28 January-4 February Published on: |
| 2020 |
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Ionospheric parameters in the European sector during the magnetic storm of August 25—26, 2018 Blagoveshchensky, DV; Sergeeva, MA; Published by: Advances in Space Research Published on: |
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Ionospheric parameters in the European sector during the magnetic storm of August 25—26, 2018 The GUVI data used here are provided through support from the NASA MO&DA program. The GUVI instrument was designed and built by The Aerospace Corporation and The Johns Blagoveshchensky, DV; Sergeeva, MA; Published by: Advances in Space Research Published on: YEAR: 2020 DOI: 10.1016/j.asr.2019.07.044 |
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We simulated the impact of long‐term changes in the geomagnetic field on the spatial pattern of the Weddell Sea Anomaly (WSA). The Weddell Sea Anomaly, belonging to the region Slominska, Ewa; Strumik, Marek; Slominski, Jan; Haagmans, Roger; Floberghagen, Rune; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2019JA027528 |
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Physical processes of meso-scale, dynamic auroral forms Meso-scale auroral forms, such as poleward boundary intensifications, streamers, omega bands, beads and giant undulations, are manifestations of dynamic processes in the magnetosphere driven, to a large part, by plasma instabilities in the magnetotail. New observations from ground- and space-based instrumentation and theoretical treatments are giving us a clearer view of some of the physical processes behind these auroral forms. However, questions remain as to how some of these observations should be interpreted, given uncertainties in mapping auroral features to locations in the magnetotatil and due to the significant overlap in the results from a variety of models of different plasma instabilities. We provide an overview of recent results in the field and seek to clarify some of the remaining questions with regards to what drives some of the largest and most dynamic auroral forms. Forsyth, C; Sergeev, VA; Henderson, MG; Nishimura, Y; Gallardo-Lacourt, B; Published by: Space Science Reviews Published on: YEAR: 2020 DOI: 10.1007/s11214-020-00665-y |
| 2019 |
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Dayside aurora is related to processes in the dayside magnetosphere and especially at the dayside magnetopause. A number of dayside aurora phenomena are driven by reconnection between the solar wind interplanetary magnetic field and the Earth\textquoterights internal magnetic field at the magnetopause. We summarize the properties and origin of aurora at the cusp foot point, High Latitude Dayside Aurora (HiLDA), Poleward Moving Auroral Forms (PMAFs), aurora related to traveling convection vortices (TCV), and throat aurora. Furthermore we discuss dayside diffuse aurora, morning side diffuse aurora spots, and shock aurora. Frey, Harald; Han, Desheng; Kataoka, Ryuho; Lessard, Marc; Milan, Stephen; Nishimura, Yukitoshi; Strangeway, Robert; Zou, Ying; Published by: Space Science Reviews Published on: 11/2019 YEAR: 2019 DOI: 10.1007/s11214-019-0617-7 |
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Variations of ionospheric parameters Total Electron Content (TEC) by GNSS, critical frequency (foF2) by vertical sounding and electron density (Ne) by low-altitude satellite were studied at high, mid and low latitudes of the European sector during the magnetic storm of August 25\textendash26, 2018. During the main phase of the storm the ionospheric F2-layer was under the positive disturbance at mid and low latitudes. Then the transition from the positive to negative ΔfoF2 values occurred at all latitudes. The recovery phase was characterized by negative ionospheric disturbance at all latitudes. This is due to the decrease of thermospheric O/N2 ratio during the recovery phase of the storm. The intense Es layers screened the reflections from the F2-layer on August 26th at high and at low latitudes but at different times. Some blackouts occurred due to the high absorption level at high latitudes. In general, foF2 and TEC data were highly correlated. The major Ne changes were at the low latitudes. In general, Ne data confirmed the ionospheric dynamics revealed with foF2 and TEC. Blagoveshchensky, D.V.; Sergeeva, M.A.; Published by: Advances in Space Research Published on: 08/2019 YEAR: 2019 DOI: 10.1016/j.asr.2019.07.044 |
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Imaging of the Daytime Ionospheric Equatorial Arcs With Extreme and Far Ultraviolet Airglow We present the first global images of the daytime ionosphere equatorial arcs as manifested in the 83.4-nm airglow. These images were collected by the Limb-Imaging Ionospheric and Thermospheric Extreme-Ultraviolet Spectrograph that commenced operations on the International Space Station in early 2017. We compare these to simultaneous images of the ionospheric radiative recombination airglow at 135.6 nm measured between 250- and 350-km tangent altitudes, where the emission is generated primarily by radiative recombination of ionospheric plasma. We find that these signatures of the dense crests of the Equatorial Ionization Anomaly, their symmetry, and daily variability at 1300\textendash1600 LT over 1\textendash6 April 2017 do not show any strong periodicity during this time. These results are also important to the joint interpretation of these two correlated extreme and far ultraviolet emission features measured under solar minimum conditions and the evaluation of absorption and radiative transfer effects that affect these emissions differently. Stephan, A.; Finn, S.; Cook, T.; Geddes, G.; Chakrabarti, S.; Budzien, S.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2019 YEAR: 2019 DOI: 10.1029/2019JA026624 |
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As part of its International Capabilities Assessment effort, the Community Coordinated Modeling Center initiated several working teams, one of which is focused on the validation of models and methods for determining auroral electrodynamic parameters, including particle precipitation, conductivities, electric fields, neutral density and winds, currents, Joule heating, auroral boundaries, and ion outflow. Auroral electrodynamic properties are needed as input to space weather models, to test and validate the accuracy of physical models, and to provide needed information for space weather customers and researchers. The working team developed a process for validating auroral electrodynamic quantities that begins with the selection of a set of events, followed by construction of ground truth databases using all available data and assimilative data analysis techniques. Using optimized, predefined metrics, the ground truth data for selected events can be used to assess model performance and improvement over time. The availability of global observations and sophisticated data assimilation techniques provides the means to create accurate ground truth databases routinely and accurately. Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; Liemohn, Michael; Weygand, James; Crowley, Geoffrey; Merkin, Viacheslav; McGranaghan, Ryan; Mannucci, Anthony; Published by: Space Weather Published on: 01/2019 YEAR: 2019 DOI: 10.1029/2018SW002127 |
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Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; , others; Published by: Space Weather Published on: |
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Park, Jong-Sun; Shi, Quanqi; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiugang; Degeling, Alexander; Tian, Anmin; Pitkänen, Timo; , others; Published by: Published on: |
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Tonolo, Federica; Salmain, Michèle; Scalcon, Valeria; Top, Siden; Pigeon, Pascal; Folda, Alessandra; Caron, Benoit; Mcglinchey, Michael; Toillon, Robert-Alain; Bindoli, Alberto; , others; Published by: ChemMedChem Published on: |
| 2018 |
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Space Weather Events, Hurricanes, and Earthquakes in Mexico in September 2017 In the interval of 4\textendash10 September 2017, the Sun presented multiple solar flares from active region AR 2673. There were also coronal mass ejections that interacted with the Earth\textquoterights magnetosphere. This solar activity produced several space weather events. These events were observed with ground-based instruments of the Mexican Space Weather Service. The Mexican Array RadioTelescope detected highly perturbed solar transits associated with Type I radio emissions from active regions. The Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories-Mexican Array RadioTelescope station detected several radio bursts including a Type III associated with the X8.2 flare on 10 September. The magnetometer detected variations reaching a regional K index of 8.3 during the geomagnetic storm. The ionosphere over Mexico was disturbed by different space weather phenomena with the dominant effects of the geomagnetic storm. We used total electron content data to study latitudinal and longitudinal ionospheric effects in this interval. The cosmic rays monitor detected a Forbush decrease associated also with the geomagnetic storm. This low-latitude instrumental network in Mexico allowed estimating the regional response to space weather events. Coincidentally with the space weather events referred above, there were also two other types of natural hazards affecting the country at that moment, the hurricane Katia category 2 in the Gulf of Mexico, and two major earthquakes (7 and 19 September 2018). The conjunction of these natural phenomena were close to creating a worst-case scenario in terms of civil protection reaction. Gonzalez-Esparza, J.; Sergeeva, M.; Corona-Romero, P.; Mejia-Ambriz, J.; Gonzalez, L.; De la Luz, V.; Aguilar-Rodriguez, E.; Rodriguez, M.; andez, Romero-Hern\; Published by: Space Weather Published on: 12/2018 YEAR: 2018 DOI: 10.1029/2018SW001995 |
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Heliophysics Science enabled by Lunar Orbiting Platforms Spann, James; Giles, Barbara; Spence, Harlan; Savage, Sabrina; Paxton, Larry; Kasper, Justin; Horanyi, Mihaly; DeLuca, Edward; Collado-Vega, Yaireska; Clark, Pamela; Published by: 2018 Triennial Earth-Sun Summit (TESS Published on: |
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Planetary Magnetospheres 60 years after Explorer 1 Published by: Published on: |
| 2017 |
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Space Physics and Aeronomy Agency Night Paxton, Larry; Wiltberger, Michael; Luce, Peg; Published by: Published on: |
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Driving of Dramatic Geomagnetic Activity by Enhancement of Meso-Scale Polar-cap Flows Lyons, Larry; Gallardo-Lacourt, Bea; Zou, Ying; Nishimura, Yukitoshi; Anderson, Phillip; Angelopoulos, VASSILIS; Ruohoniemi, Michael; Mitchell, Elizabeth; Paxton, Larry; Nishitani, Nozomu; Published by: Published on: |
| 2016 |
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Ionospheric responses to geomagnetic storms during 2015-2016 at longitude 120° E in China Chen, Yanhong; Tianjiao, Yuan; Hua, Shen; Liu, Siqing; Wengeng, Huang; Gong, Jiancun; Published by: Published on: |
| 2015 |
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Electron precipitation models in global magnetosphere simulations General methods for improving the specification of electron precipitation in global simulations are described and implemented in the Lyon-Fedder-Mobarry (LFM) global simulation model, and the quality of its predictions for precipitation is assessed. LFM\textquoterights existing diffuse and monoenergetic electron precipitation models are improved, and new models are developed for lower energy, broadband, and direct-entry cusp precipitation. The LFM simulation results for combined diffuse plus monoenergetic electron precipitation exhibit a quadratic increase in the hemispheric precipitation power as the intensity of solar wind driving increases, in contrast with the prediction from the OVATION Prime (OP) 2010 empirical precipitation model which increases linearly with driving intensity. Broadband precipitation power increases approximately linearly with driving intensity in both models. Comparisons of LFM and OP predictions with estimates of precipitating power derived from inversions of Polar satellite UVI images during a double substorm event (28\textendash29 March 1998) show that the LFM peak precipitating power is \>4\texttimes larger when using the improved precipitation model and most closely tracks the larger of three different inversion estimates. The OP prediction most closely tracks the double peaks in the intermediate inversion estimate, but it overestimates the precipitating power between the two substorms by a factor \>2 relative to all other estimates. LFMs polar pattern of precipitating energy flux tracks that of OP for broadband precipitation exhibits good correlation with duskside region 1 currents for monoenergetic energy flux that OP misses and fails to produce sufficient diffuse precipitation power in the prenoon quadrant that is present in OP. The prenoon deficiency is most likely due to the absence of drift kinetic physics in the LFM simulation. Zhang, B.; Lotko, W.; Brambles, O.; Wiltberger, M.; Lyon, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2015 YEAR: 2015 DOI: 10.1002/2014JA020615 electron precipitation; global magnetosphere simulation; magnetosphere-ionosphere coupling |
| 2014 |
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Solar filament impact on 21 January 2005: Geospace consequences On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere\textemdashan unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks\textemdashhigh enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1\textendash2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material. Kozyra, J.; Liemohn, M.; Cattell, C.; De Zeeuw, D.; Escoubet, C.; Evans, D.; Fang, X.; Fok, M.-C.; Frey, H.; Gonzalez, W.; Hairston, M.; Heelis, R.; Lu, G.; Manchester, W.; Mende, S.; Paxton, L.; Rastaetter, L.; Ridley, A.; Sandanger, M.; Soraas, F.; Sotirelis, T.; Thomsen, M.; Tsurutani, B.; Verkhoglyadova, O.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2014 YEAR: 2014 DOI: 10.1002/2013JA019748 cold dense plasma sheet; Equatorial anomaly; magnetotail; precipitation; prompt penetration electric field; solar filament |
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Auroral all-sky camera calibration A two-step procedure to calibrate the spectral sensitivity to visible light of auroral all-sky cameras is outlined. Center pixel response is obtained by the use of a Lambertian surface and a Sigernes, Fred; Holmen, SE; Biles, D; Bj\orklund, H; Chen, X; Dyrland, M; Lorentzen, DA; Baddeley, L; Trondsen, T; Brändström, U; , others; Published by: Geoscientific Instrumentation, Methods and Data Systems Published on: YEAR: 2014 DOI: 10.5194/gi-3-241-2014 |
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Burns, Erick; Williams, Colin; Ingebritsen, Steve; Voss, Clifford; Spane, Frank; DeAngelo, Jake; Published by: Published on: |
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Burns, Erick; Williams, Colin; Ingebritsen, Steve; Voss, Clifford; Spane, Frank; DeAngelo, Jake; Published by: Published on: |
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Ionospheric Data Assimilation from a Data Provider's Perspective Schaefer, Robert; Paxton, Larry; Bust, G; Zhang, Yongliang; Romeo, Giuseppe; Comberiate, Joseph; Gelinas, Lynette; Published by: Published on: |
| 2013 |
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Ion-neutral coupling during deep solar minimum The equatorial ionosphere under conditions of deep solar minimum exhibits structuring due to tidal forces. Data from instruments carried by the Communication/Navigation Outage Forecasting System (C/NOFS) which was launched in April 2008 have been analyzed for the first 2 years following launch. The Planar Langmuir Probe (PLP), Ion Velocity Meter (IVM) and Vector Electric Field Investigation (VEFI) all detect periodic structures during the 2008\textendash2010 period which appear to be tides. However when the tidal features detected by these instruments are compared, there are distinctive and significant differences between the observations. Tides in neutral densities measured by the Gravity Recovery and Climate Experiment (GRACE) satellite were also observed during June 2008. In addition, Broad Plasma Decreases (BPDs) appear as a deep absolute minimum in the plasma and neutral density tidal pattern. These are co-located with regions of large downward-directed ion meridional velocities and minima in the zonal drifts, all on the nightside. The region in which BPDs occur coincides with a peak in occurrence rate of dawn depletions in plasma density observed on the Defense Meterological Satellite Program (DMSP) spacecraft, as well as a minimum in radiance detected by UV imagers on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) and IMAGE satellites. Huang, Cheryl; Roddy, Patrick; Sutton, Eric; Stoneback, Russell; Pfaff, Robert; Gentile, Louise; Delay, Susan; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 10/2013 YEAR: 2013 DOI: 10.1016/j.jastp.2012.11.009 Equatorial ionosphere; Nonmigrating tides; Plasma depletions; thermosphere |
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Determination of the Ionospheric Electron Density Profile from FUV Remote Sensing Measurements A limb viewing model is established in this paper based on GUVI measurements of OI 135.6 nm nightglow and a method with Chapman function describing the distribution of ionospheric electron density is presented to obtain the ionospheric electron density profile. We apply the regularization and Newton iteration method to calculate ionospheric peak electron density and peak height with GUVI measurements, eliminating the ill condition of the weighted matrix. The ionospheric electron density profile is obtained using the calculated peak electron density and peak height as inputs. To evaluate the fidelity of the proposed algorithm in this paper, the retrieved electron density profiles are compared with those from ground-based observations. The results show that the retrieved electron density profiles agree well with those from ISR. Afterwards, the effects of magnetic storms on EDP are studied with the retrieved EDPs of the period between Sep 29 and Oct 3, 2002. Jing, Wang; Yi, TANG; Zhi-Ge, ZHANG; Xu-Li, ZHENG; Guo-Qiang, NI; Published by: Chinese Journal of Geophysics Published on: 03/2013 YEAR: 2013 DOI: 10.1002/cjg2.20011 Electron density profile; Far ultraviolet spectrum remote sensing; GUVI; Ionosphere |
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We study solar wind\textendashionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) \textendash 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10\textendash22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008\textendash2009 were similar but ~60\% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed. Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Runge, T.; Published by: Annales Geophysicae Published on: 01/2013 YEAR: 2013 DOI: 10.5194/angeo-31-263-2013 |
| 2012 |
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Burns, A.G.; Solomon, S.C.; Qian, L.; Wang, W.; Emery, B.A.; Wiltberger, M.; Weimer, D.R.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-07-2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.02.006 |
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Park, Jaeheung; Lühra, Hermann; Jakowski, Norbert; Gerzen, Tatjana; Kil, Hyosub; Jee, Geonhwa; Xiong, Chao; Min, Kyoung; Noja, Max; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-05-2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.03.009 |
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Solomon, Stanley; Burns, Alan; Emery, Barbara; Mlynczak, Martin; Qian, Liying; Wang, Wenbin; Weimer, Daniel; Wiltberger, Michael; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017417 |
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The main objective of the present investigation has been to compare the ionospheric parameters (NmF2 and hmF2) observed by two ground-based ionospheric sounders (one at PALMAS- located near the magnetic equator and the other at Sao Jose dos Campos-located in the low-latitude region) in the Brazilian sector with that by the satellite FORMOSAT-3/COSMIC radio occultation (RO) measurements during two geomagnetic storms which occurred in December 2006 and July 2009. It should be pointed out that in spite of increasing the latitude (to 10\textdegree) and longitude (to 20\textdegree) around the stations; we had very few common observations. It has been observed that both the peak electron density (NmF2) and peak height (hmF2) observed by two different techniques (space-borne COSMIC and ground-based ionosondes) during both the geomagnetic storm events compares fairly well (with high correlation coefficients) at the two stations in the Brazilian sector. It should be pointed out that due to equatorial spread F (ESF) in the first storm (December 2006) and no-reflections from the ionosphere during nighttime in the second storm (July 2009), we had virtually daytime data from the two ionosondes. Sahai, Y.; de Jesus, R.; Fagundes, P.R.; Selhorst, C.L.; de Abreu, A.J.; Ram, Tulasi; Aragon-Angel, A.; Pillat, V.G.; Abalde, J.R.; Lima, W.L.C.; Bittencourt, J.A.; Published by: Advances in Space Research Published on: 11/2012 YEAR: 2012 DOI: 10.1016/j.asr.2012.07.006 COSMIC satellite; F-region; geomagnetic storm; Ionosphere; Low solar activity |
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The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth\textquoterights upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105\ nm with unprecedented spectral resolution (0.1\ nm), temporal cadence (ten seconds), and accuracy (20\%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37\ nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105\ nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39\ nm, and a MEGS-Photometer measures the Sun\textquoterights bright hydrogen emission at 121.6\ nm. The EVE data products include a near real-time space-weather product (Level\ 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15\ minutes. The EVE higher-level products are Level\ 2 with the solar EUV irradiance at higher time cadence (0.25\ seconds for photometers and ten seconds for spectrographs) and Level\ 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth\textquoterights ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team. Woods, T.; Eparvier, F.; Hock, R.; Jones, A.; Woodraska, D.; Judge, D.; Didkovsky, L.; Lean, J.; Mariska, J.; Warren, H.; McMullin, D.; Chamberlin, P.; Berthiaume, G.; Bailey, S.; Fuller-Rowell, T.; Sojka, J.; Tobiska, W.; Viereck, R.; Published by: Solar Physics Published on: 01/2012 YEAR: 2012 DOI: 10.1007/s11207-009-9487-6 |
| 2011 |
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Verkhoglyadova, O.; Tsurutani, B.; Mannucci, A.; Mlynczak, M.; Hunt, L.; Komjathy, A.; Runge, T.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011 DOI: 10.1029/2011JA016604 |
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Sahai, Y; De Abreu, AJ; Fagundes, PR; De Jesus, R; Crowley, G; Klimenko, MV; Klimenko, VV; Brunini, C; Gende, M; Pillat, VG; , others; Published by: Asian Journal of Physics Published on: |
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Two methods to forecast auroral displays Sigernes, Fred; Dyrland, Margit; Brekke, P\aal; Chernouss, Sergey; Lorentzen, Dag; Oksavik, Kjellmar; Deehr, Charles; Published by: Journal of Space Weather and Space Climate Published on: |
| 2010 |
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Ionospheric response to the initial phase of geomagnetic storms: Common features Wang, Wenbin; Lei, Jiuhou; Burns, Alan; Solomon, Stanley; Wiltberger, Michael; Xu, JiYao; Zhang, Yongliang; Paxton, L.; Coster, Anthea; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JA014461 |
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Gattinger, R.; McDade, I.; an, A.; Boone, C.; Walker, K.; Bernath, P.; Evans, W.; Degenstein, D.; Yee, J.-H.; Sheese, P.; Llewellyn, E.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JD013205 |
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Gattinger, R.; McDade, I.; an, A.; Boone, C.; Walker, K.; Bernath, P.; Evans, W.; Degenstein, D.; Yee, J.-H.; Sheese, P.; Llewellyn, E.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JD013205 |
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Gattinger, RL; McDade, IC; an, AL; Boone, CD; Walker, KA; Bernath, PF; Evans, WFJ; Degenstein, DA; Yee, J-H; Sheese, P; , others; Published by: Journal of Geophysical Research: Atmospheres Published on: |
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Gattinger, RL; McDade, IC; an, AL; Boone, CD; Walker, KA; Bernath, PF; Evans, WFJ; Degenstein, DA; Yee, J-H; Sheese, P; , others; Published by: Journal of Geophysical Research: Atmospheres Published on: |
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Canary: Ion spectroscopy for ionospheric sensing Feldmesser, HS; Darrin, MAG; Osiander, R; Paxton, LJ; Rogers, AQ; Marks, JA; McHarg, MG; Balthazor, RL; Krause, LH; FitzGerald, JG; Published by: Published on: |
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