Bibliography
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Found 178 entries in the Bibliography.
Showing entries from 51 through 100
| 2017 |
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Impact of the lower thermospheric winter-to-summer residual circulation on thermospheric composition Gravity wave forcing near the mesopause drives a summer-to-winter residual circulation in the mesosphere and a reversed, lower thermospheric winter-to-summer residual circulation. We conducted modeling studies to investigate how this lower thermospheric residual circulation impacts thermospheric composition (O/N2). We found that the upwelling associated with the residual circulation significantly decreases O/N2 in winter and the downwelling in summer slightly increases O/N2. Consequently, the residual circulation reduces the summer-to-winter latitudinal gradient of O/N2, which causes the simulated latitudinal gradient of O/N2 to be more consistent with observations. The smaller summer-to-winter latitudinal gradient of O/N2 would decrease the ionosphere winter anomaly in model simulations, which would bring the simulated winter anomaly into better agreement with ionospheric observations. The lower thermospheric residual circulation may be a process that has been largely ignored but is very important to the summer-to-winter latitudinal gradients, as well as annual/semiannual variations in the thermosphere and ionosphere. Published by: Geophysical Research Letters Published on: 05/2017 YEAR: 2017 DOI: 10.1002/2017GL073361 |
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MONITOR ionospheric network: two case studies on scintillation and electron content variability The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study eniguel, Yannick; Cherniak, Iurii; Garcia-Rigo, Alberto; Hamel, Pierrick; andez-Pajares, Manuel; Kameni, Roland; Kashcheyev, Anton; Krankowski, Andrzej; Monnerat, Michel; Nava, Bruno; , others; Published by: Published on: YEAR: 2017 DOI: 10.5194/angeo-35-377-2017 |
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MONITOR ionospheric network: two case studies on scintillation and electron content variability The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study eniguel, Yannick; Cherniak, Iurii; Garcia-Rigo, Alberto; Hamel, Pierrick; andez-Pajares, Manuel; Kameni, Roland; Kashcheyev, Anton; Krankowski, Andrzej; Monnerat, Michel; Nava, Bruno; , others; Published by: Published on: YEAR: 2017 DOI: 10.5194/angeo-35-377-2017 |
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Observations of the Weddell Sea Anomaly in the ground-based and space-borne TEC measurements The Weddell Sea Anomaly (WSA) is a summer ionospheric anomaly, which is characterized by a greater nighttime ionospheric density than that in daytime in the region near the Weddell Sea. We investigate the WSA signatures in the ground-based TEC (vertical total electron content) by using GPS and GLONASS measurements of the dense regional GNSS networks in South America. We constructed the high-resolution regional TEC maps for December 2014–January 2015. The WSA effects of the TEC exceed the noontime values are registered starting from 17 LT, it reaches its maximum at 01–05 LT and starts to disappear after 09 LT. Zakharenkova, Irina; Cherniak, Iurii; Shagimuratov, Irk; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2017 DOI: 10.1016/j.jastp.2017.06.014 |
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Good ionospheric modeling is important to understand anomalous effects, mainly during geomagnetic storm events. Ionospheric electric fields, thermospheric winds, and neutral composition are affected at different degrees, depending on the intensity of the magnetic disturbance which, in turns, affects the electron density distribution at all latitudes. The most important disturbed parameter for the equatorial ionosphere is the electric field, which is responsible for the equatorial ionization anomaly. Bravo, MA; Batista, IS; , Souza; Foppiano, AJ; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2017 DOI: 10.1002/2017JA024265 |
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QUASI-BIENNIAL VARIATIONS IN IONOSPHERIC TIDAL/SPW AMPLITUDES: OBSERVATIONS AND MODELING Loren, Cheewei; Yan-Yi, Sun; Jack, Chieh; Shih-Han, Chien; Rung, Tsai-Lin; Jia, Yue; Published by: Published on: |
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Burns, Alan; Wang, Wenbin; Zhang, Yongliang; Qian, Liying; Published by: Published on: |
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Analysis and design of the ultraviolet warning optical system based on interference imaging Ultraviolet warning technology is one of the important methods for missile warning. It provides a very effective way to detect the target for missile approaching alarm. With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important role. Compared to infrared warning, the ultraviolet warning has high efficiency and low false alarm rate. In the modern warfare, how to detect the threats earlier, prevent and reduce the attack of precision-guided missile has become a new challenge of missile warning technology. Because the ultraviolet warning technology has high environmental adaptability, the low false alarm rate, small volume and other advantages, in the military field applications it has been developed rapidly. For the ultraviolet warning system, the optimal working waveband is 250 nm ~280 nm (Solar Blind UV) due to the strong absorption of ozone layer. According to current application demands for solar blind ultraviolet detection and warning, this paper proposes ultraviolet warning optical system based on interference imaging, which covers solar blind ultraviolet (250nm-280nm) and dual field. This structure includes a primary optical system, an ultraviolet reflector array, an ultraviolet imaging system and an ultraviolet interference imaging system. It makes use of an ultraviolet beam-splitter to achieve the separation of two optical systems. According to the detector and the corresponding application needs of two visual field of the optical system, the calculation and optical system design were completed. After the design, the MTF of the two optical system is more than 0.8@39lp/mm.A single pixel energy concentration is greater than 80\%. Wencong, Wang; Jin, Dong-dong; Chu, Xin-bo; Shi, Yu-feng; Song, Juan; Liu, Jin-sheng; Shao, Si-pei; Hu, Hui-jun; Xiao, Ting; Published by: Published on: YEAR: 2017 DOI: 10.1117/12.2285832 |
| 2016 |
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This work estimates global-mean Kzz using Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics monthly global-mean CO2 profiles and a one-dimensional transport model. It is then specified as a lower boundary into the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). Results first show that global-mean CO2 in the mesosphere and lower thermosphere region has annual and semiannual oscillations (AO and SAO) with maxima during solstice seasons along with a primary maximum in boreal summer. Our calculated AO and SAO in global-mean CO2 are then modeled by AO and SAO in global-mean Kzz. It is then shown that our estimated global-mean Kzz is lower in magnitude than the suggested global-mean Kzz from Qian et al. (2009) that can model the observed AO and SAO in the ionosphere/thermosphere (IT) region. However, our estimated global-mean Kzz is similar in magnitude with recent suggestions of global-mean Kzz in models with explicit gravity wave parameterization. Our work therefore concludes that global-mean Kzz from global-mean CO2 profiles cannot model the observed AO and SAO in the IT region because our estimated global-mean Kzz may only be representing eddy diffusion due to gravity wave breaking. The difference between our estimated global-mean Kzz and the global-mean Kzz from Qian et al. (2009) thus represents diffusion and mixing from other nongravity wave sources not directly accounted for in the TIE-GCM lower boundary conditions. These other sources may well be the more dominant lower atmospheric forcing behind the AO and SAO in the IT region. Salinas, Cornelius; Chang, Loren; Liang, Mao-Chang; Yue, Jia; Russell, James; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2016 YEAR: 2016 DOI: 10.1002/2016JA023161 |
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We present an analysis of ionospheric irregularities at high latitudes during the 2015 St. Patrick\textquoterights Day storm. Our study used measurements from\ ~2700 ground-based GPS stations and GPS receivers onboard five low earth orbit (LEO) satellites\textemdashSwarm A, B and C, GRACE and TerraSAR-X\textemdashthat had close orbit altitudes of\ ~500\ km, and the Swarm in situ plasma densities. An analysis of the rate of TEC index (ROTI) derived from LEO\textendashGPS data, together with Swarm in situ plasma probe data, allowed us to examine the topside ionospheric irregularities and to compare them to the main ionospheric storm effects observed in ground-based GPS data. We observed strong ionospheric irregularities in the topside ionosphere during the storm\textquoterights main phase that were associated with storm-enhanced density (SED) formation at mid-latitudes and further evolution of the SED plume to the polar tongue of ionization (TOI). Daily ROTI maps derived from ground-based and LEO\textendashGPS measurements show the pattern of irregularities oriented in the local noon\textendashmidnight direction, which is a signature of SED/TOI development across the polar cap region. Analysis of the Swarm in situ plasma measurements revealed that, during the storm\textquoterights main phase, all events with extremely enhanced plasma densities (\>106\ el/cm3) in the polar cap were observed in the Southern Hemisphere. When Swarm satellites crossed these enhancements, degradation of GPS performance was observed, with a sudden decrease in the number of GPS satellites tracked. Our findings indicate that polar patches and TOI structures in the topside ionosphere were predominantly observed in the Southern Hemisphere, which had much higher plasma densities than the Northern Hemisphere, where SED/TOI structures have already been reported earlier. LEO\textendashGPS data (ROTI and topside TEC) were consistent with these results. Cherniak, Iurii; Zakharenkova, Irina; Published by: Earth, Planets and Space Published on: 07/2016 YEAR: 2016 DOI: 10.1186/s40623-016-0506-1 |
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Longitudinal variations of thermospheric composition at the solstices O/N2, measured by the Global Ultraviolet Imager on board the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, has large longitudinal variations at the solstices, which are simulated well in upper atmosphere general circulation models. These longitudinal variations are caused by the displacement of the Earth\textquoterights magnetic poles from the geographic ones. The location of a magnetic pole affects the latitude at which the winds, driven by heating in summer, converge in the subauroral region of the winter hemisphere. In the magnetic pole\textquoterights longitude sector, this convergence occurs at relatively low latitudes, which results in the maximum values of O/N2 also occurring at relatively low latitudes. These latitudes have a relatively small solar zenith angle, contributing to a strong winter anomaly. In the zonally opposite longitude sector, maximum values of O/N2 occur at relatively high latitudes because the summer-to-winter wind convergence also occurs at relatively high latitudes. These high latitudes have a relatively large solar zenith angle, so ionization is weak, contributing to a weak winter anomaly. Therefore, the displacement between the magnetic and geographic poles not only results in a strong longitudinal variation of O/N2 but also results in a strong longitudinal variation of the ionosphere winter anomaly. Qian, Liying; Burns, Alan; Wang, Wenbin; Solomon, Stanley; Zhang, Yongliang; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2016 YEAR: 2016 DOI: 10.1002/2016JA022898 |
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Solar cycle variations of thermospheric composition at the solstices We examine the solar cycle variability of thermospheric composition (O/N2) at the solstices. Our observational and modeling studies show that the summer-to-winter latitudinal gradient of O/N2 is small at solar minimum but large at solar maximum; O/N2 is larger at solar maximum than at solar minimum on a global-mean basis; there is a seasonal asymmetry in the solar cycle variability of O/N2, with large solar cycle variations in the winter hemisphere and small solar cycle variations in the summer hemisphere. Model analysis reveals that vertical winds decrease the temperature-driven solar cycle variability in the vertical gradient of O/N2 in the summer hemisphere but increase it in the winter hemisphere; consequently, the vertical gradient of O/N2 does not change much in the summer hemisphere over a solar cycle, but it increases greatly from solar minimum to solar maximum in the winter hemisphere; this seasonal asymmetry in the solar cycle variability in the vertical gradient of O/N2 causes a seasonal asymmetry in the vertical advection of O/N2, with small solar cycle variability in the summer hemisphere and large variability in the winter hemisphere, which in turn drives the observed seasonal asymmetry in the solar cycle variability of O/N2. Since the equatorial ionization anomaly suppresses upwelling in the summer hemisphere and strengthens downwelling in the winter hemisphere through plasma-neutral collisional heating and ion drag, locations and relative magnitudes of the equatorial ionization anomaly crests and their solar cycle variabilities can significantly impact the summer-to-winter gradients of O/N2 and their solar cycle variability. Qian, Liying; Burns, Alan; Solomon, Stanley; Wang, Wenbin; Zhang, Yongliang; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2016 YEAR: 2016 DOI: 10.1002/2016JA022390 |
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Thermospheric hydrogen response to increases in greenhouse gases We investigated thermospheric hydrogen response to increase in greenhouse gases and the dependence of this response to solar activity, using a global mean version of the National Center for Atmospheric Research Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model. We separately doubled carbon dioxide (CO2) and methane (CH4) to study the influence of temperature and changes to source species for hydrogen. Our results indicate that both CO2 cooling and CH4 changes to the source species for hydrogen lead to predicted increases in the upper thermospheric hydrogen density. At 400 km, hydrogen increases ~30\% under solar maximum and ~25\% under solar minimum responding to doubling of CH4, indicating that hydrogen response to the source variation due to CH4 increase is relatively independent of solar activity. On the other hand, hydrogen response to doubling of CO2 highly depends on solar activity. At 400 km, doubling of CO2 results in an ~7\% hydrogen increase at solar maximum, whereas it is ~25\% at solar minimum. Consequently, at solar maximum, the predicted ~40\% increase in atomic hydrogen in the upper thermosphere is primarily due to the source variation as a result of doubling of CH4, whereas at solar minimum, both cooling due to doubling of CO2 and the source variation due to doubling of CH4 have commensurate effects, resulting in an approximate 50\% increase in the modeled upper thermospheric hydrogen. Nossal, S.; Qian, L.; Solomon, S.; Burns, A.; Wang, W.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2016 YEAR: 2016 DOI: 10.1002/2015JA022008 |
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We investigate the interhemispheric circulation at the solstices, in order to understand why O/N2\ is larger in the northern hemisphere winter than in the southern hemisphere winter. Our studies reveal that the equatorial ionosphere anomaly (EIA) significantly impacts the summer-to-winter wind through plasma-neutral collisional heating, which changes the summer-to-winter pressure gradient, and ion drag. Consequently, the wind is suppressed in the summer hemisphere as it encounters the EIA but accelerates after it passes the EIA in the winter hemisphere. The wind then converges due to an opposing pressure gradient driven by Joule heating in auroral regions and produces large O/N2\ at subauroral latitudes. This EIA effect is stronger near the December solstice than near the June solstice because the ionospheric annual asymmetry creates greater meridional wind convergence near the December solstice, which in turn produces larger O/N2\ in the northern hemisphere winter than in the southern hemisphere winter. Qian, Liying; Burns, Alan; Wang, Wenbin; Solomon, Stanley; Zhang, Yongliang; Hsu, V.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2016 YEAR: 2016 DOI: 10.1002/2015JA022169 Equatorial ionization anomaly; interhemispheric circulation; ionosphere winter anomaly; plasma-neutral collisional heating; thermosphere composition; vertical advection |
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This work estimates global‐mean K zz using Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics Salinas, Cornelius; Chang, Loren; Liang, Mao-Chang; Yue, Jia; , Russell; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2016 DOI: 10.1002/2016JA023161 |
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We present an analysis of ionospheric irregularities at high latitudes during the 2015 St. Patrick’s Day storm. Our study used measurements from ~2700 ground-based GPS stations and Cherniak, Iurii; Zakharenkova, Irina; Published by: Earth, Planets and Space Published on: YEAR: 2016 DOI: 10.1186/s40623-016-0506-1 |
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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: |
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Burns, Alan; Qian, Liying; Wang, Wenbin; Goncharenko, Larisa; Solomon, Stanley; Published by: Published on: |
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Effects of the equatorial ionosphere anomaly on the interhemispheric circulation in the thermosphere Qian, Liying; Burns, Alan; Wang, Wenbin; Solomon, Stanley; Zhang, Yongliang; , Hsu; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2015 |
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The magnetosphere substorm plays a crucial role in the solar wind energy dissipation into the ionosphere. We report on the intensity of the high-latitude ionospheric irregularities during one of the largest storms of the current solar cycle\textemdashthe St. Patrick\textquoterights Day storm of 17 March 2015. The database of more than 2500 ground-based Global Positioning System (GPS) receivers was used to estimate the irregularities occurrence and dynamics over the auroral region of the Northern Hemisphere. We analyze the dependence of the GPS-detected ionospheric irregularities on the auroral activity. The development and intensity of the high-latitude irregularities during this geomagnetic storm reveal a high correlation with the auroral hemispheric power and auroral electrojet indices (0.84 and 0.79, respectively). Besides the ionospheric irregularities caused by particle precipitation inside the polar cap region, evidences of other irregularities related to the storm enhanced density (SED), formed at mid-latitudes and its further transportation in the form of tongue of ionization (TOI) towards and across the polar cap, are presented. We highlight the importance accounting contribution of ionospheric irregularities not directly related with particle precipitation in overall irregularities distribution and intensity. Cherniak, Iurii; Zakharenkova, Irina; Published by: Earth, Planets and Space Published on: 12/2015 YEAR: 2015 DOI: 10.1186/s40623-015-0316-x Auroral hemispheric power index Auroral precipitation; geomagnetic storm; GPS; Ionosphere irregularities; ROTI |
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Towards estimation of atmospheric tidal effects on the ionosphere via data assimilation The impact of atmospheric tides on the night time ionosphere is now being a subject of the extensive research within the scientific community. The plausible effect has been observed using the multiple space-borne instruments (e.g. COSMIC/FORMOSAT-3 constellation, TIMED GUVI and NASA IMAGE). Along with the observations, several modelling attempts has been undertaken to prove or refute the interrelation between the atmospheric tides and the wave-four longitudinal night time ionosphere structure. The scope of the current article is to assess the data assimilation ionosphere model capabilities in representing the longitudinal effect in the night time ionosphere induced by the DE3 atmospheric tide. Along with this, the core physics-based model capabilities in estimating the same effect are presented and discussed. For the current research, two periods were taken into consideration: the autumn equinox of the years 2006 and 2012. In the current article the data assimilation and physics-based models calculation results are presented and discussed along with the models\textquoteright error estimation and analysis. Solomentsev, Dmitry; Cherniak, Yakov; Titov, Anton; Khattatov, Boris; Khattatov, Vyacheslav; Published by: Advances in Space Research Published on: 11/2015 YEAR: 2015 DOI: 10.1016/j.asr.2015.07.014 Atmosphere tides; data assimilation; Ionosphere longitudinal structure |
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We report first results on the study of the high-latitude ionospheric irregularities observed in worldwide GPS data during the St. Patrick\textquoterights Day geomagnetic storm (17 March 2015). Multisite GPS observations from more than 2500 ground-based GPS stations were used to analyze the dynamics of the ionospheric irregularities in the Northern and Southern Hemispheres. The most intense ionospheric irregularities lasted for more than 24 h starting at 07 UT of 17 March. This period correlates well with an increase of the auroral Hemispheric Power index. We find hemispheric asymmetries in the intensity and spatial structure of the ionospheric irregularities. Over North America, the ionospheric irregularities zone expanded equatorward below ~45\textdegreeN geographic latitude. Additionally, the strong midlatitude and high-latitude GPS phase irregularities in the auroral oval were found to be related to the formation of storm enhanced density and deepening of the main ionospheric trough through upper atmosphere ionization by energetic particle precipitation. Significant increases in the intensity of the irregularities within the polar cap region of both hemispheres were associated with the formation and evolution of the storm enhanced density/tongue of ionization structures and polar patches. Cherniak, Iurii; Zakharenkova, Irina; Redmon, Robert; Published by: Space Weather Published on: 09/2015 YEAR: 2015 DOI: 10.1002/swe.v13.910.1002/2015SW001237 auroral precipitation; geomagnetic storm; Ionosphere; irregularities; rate of TEC |
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Explaining solar cycle effects on composition as it relates to the winter anomaly The solar cycle variation of\ F2\ region winter anomaly is related to solar cycle changes in the latitudinal winter-to-summer difference of O/N2. Here we use the National Center for Atmospheric Research\textendashGlobal Mean Model to develop a concept of why the latitudinal winter-to-summer difference of O/N2\ varies with solar cycle. The main driver for these seasonal changes in composition is vertical advection, which is expressed most simply in pressure coordinates. Meridional winds do not change over the solar cycle, so the vertical winds should also not change. The other component of vertical advection is the vertical gradient of composition. Is there any reason that this should change? At solar maximum vertical temperature gradients between 100 and 200 km altitude are strong, whereas they are weak at solar minimum. To maintain the same pressure, the weak vertical temperature gradients at solar minimum must be balanced by weak density gradients and the strong temperature gradients at solar maximum must be balanced by strong density gradients to obtain the same pressure profile. Changes in the vertical density gradients are species dependent: heavy species change more and light species change less than the average density change. Hence, vertical winds act on stronger O/N2\ gradients at solar maximum than they do at solar minimum, and a stronger winter-to-summer difference of O/N2\ occurs at solar maximum compared with solar minimum. Burns, A.; Solomon, S.; Wang, W.; Qian, L.; Zhang, Y.; Paxton, L.; Yue, X.; Thayer, J.; Liu, H.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2015 YEAR: 2015 DOI: 10.1002/2015JA021220 |
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We studied the contribution of the global plasmaspheric and ionospheric electron content (PEC and IEC) into total electron content (TEC). The experimental PEC was estimated by comparison of GPS TECobservations and FORMOSAT-3/COSMIC radio occultation IEC measurements. Results are retrieved for the winter solstice (January and December 2009) conditions. Global maps of COSMIC-derived IEC, PECand GPS TEC were compared with Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) results. In addition, we used GSM TIP model results in order to estimate the contribution of plasmaspheric electron content into TEC value at the different altitudinal regions. The advantages and problems of the outer ionospheric/plasmaspheric parameters (O+/H+ transition height,TEC and electron density at height above F2 layer peak) representation by the IRI (International Reference Ionosphere) model are discussed. Klimenko, M.V.; Klimenko, V.V.; Zakharenkova, I.E.; Cherniak, Iu.V.; Published by: Advances in Space Research Published on: 06/2014 YEAR: 2015 DOI: 10.1016/j.asr.2014.06.027 FORMOSAT-3/COSMIC; GPS; Numerical modeling; Plasmasphere; total electron content |
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Characteristics and mechanisms of the annual asymmetry of thermospheric mass density In this paper, globally-averaged, thermospheric total mass density, derived from the orbits of \~5000 objects at 250, 400, and 550 km that were tracked from 1967 to 2006, has been used to quantitatively study the annual asymmetry of thermospheric mass density and its mechanism(s). The results show that thermospheric mass density had a significant annual asymmetry, which changed from year to year. The annual asymmetry at the three altitudes varied synchronously and its absolute value increased with altitudes. The results suggest that there is an annual asymmetry in solar EUV radiation that is caused by the difference in the Sun-Earth distance between the two solstices and the random variation of solar activity within a year. This change in radiation results in an annual change in the thermospheric temperature and thus the scale height of the neutral gas, and is the main cause of the annual asymmetry of thermospheric mass density. The annual asymmetry of mass density increases with altitude because of the accumulating effect of the changes in neutral temperature and scale height in the vertical direction. Ma, RuiPing; Xu, JiYao; Wang, Wenbin; Chen, GuangMing; Yuan, Wei; Lei, Jiuhou; Burns, Alan; Jiang, Guoying; Published by: Science China Earth Sciences Published on: 04/2015 YEAR: 2015 DOI: 10.1007/s11430-014-5020-3 annual asymmetry of thermospheric mass density; solar EUV radiation; Sun-Earth distance |
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This paper presents an epoch analysis of global ionosphere responses to recurrent geomagnetic activity during 79 corotating interaction region (CIR) events from 2004 to 2009. The data used were GPS total electron content (TEC) data from the Madrigal Database at the Massachusetts Institute of Technology Haystack Observatory and the electron density (Ne) data obtained from CHAllenging Minisatellite Payload (CHAMP) observations. The results show that global ionosphere responses to CIR events have some common features. In high and middle latitudes, the total electron content (TEC) showed a significant positive response (increased electron densities) in the first epoch day. A negative TEC response occurred at high latitudes of the American sector following the positive response. The CHAMP Ne showed a daytime positive response in all latitudes and a nighttime negative response in the subauroral region. These negative TEC and Ne responses were found to be related to thermospheric composition (O/N2) changes during the storms. At all latitudes, the maximum of the TEC positive effect always occurred at 2\textendash6 h after the CIR starting during local daytime and 10\textendash18 h later for the CIR onset during local nighttime. Case studies indicate that the TEC and Ne positive response had a strong dependence on the southward component (Bz) of the interplanetary magnetic field and solar wind speed. This suggests that penetration electric fields that were associated with changes in solar winds might play a significant role in the positive ionospheric response to storms. During the recovery time of the CIR-produced geomagnetic activity, the TEC positive disturbance at low latitudes sometimes could last for 2\textendash4 days, whereas at middle to high latitudes the disturbance lasted only for 1 day in most cases. A comparison of the ionospheric responses between the American, European and Asian sectors shows that the ionosphere response in the North American sector was stronger than that in the other two regions. The response of foF2 to the CIR events in middle to high latitudes showed a negative response for 2\textendash3 days after the first epoch day. This is different from the response of TEC, which was mostly positive during the same period of time. Chen, Yanhong; Wang, Wenbin; Burns, Alan; Liu, Siqing; Gong, Jiancun; Yue, Xinan; Jiang, Guoying; Coster, Anthea; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2015 YEAR: 2015 DOI: 10.1002/2014JA020657 CIR events; epoch study; Ionospheric response; recurrent geomagnetic activity |
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Far ultraviolet nighttime ionospheric photometer Far Ultraviolet Nighttime Ionopsheric Photometer (FNIP) is a newly-designed instrument for low earth orbit missions, observing the earth night airglow nadir at OI 135.6\ nm emission produced by ionospheric O++e recombination and receiving the horizontal information on nighttime ionosphere with a spatial resolution of about 1.6o\texttimes3.8o. This simple, highly robust instrument excludes OI 130.4 nm emission and Herzberg oxygen bands with lower power and approximately achieves a sensitivity of about 400\ counts/s/Rayleigh at 135.6\ nm with stray light less than\ 2\ \%. Some tests of the instrument have been conducted and the results will be discussed in the end. Fu, Liping; Peng, Ruyi; Shi, Entao; Peng, Jilong; Wang, Tianfang; Jiang, Fang; Jia, Nan; Li, Xiaoyin; Wang, YongMei; Published by: Astrophysics and Space Science Published on: 01/2015 YEAR: 2015 DOI: 10.1007/s10509-014-2139-9 F2 electron density distribution; FUV optical sensing remote; High sensitivity; Ionosphere; Payload |
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Far ultraviolet nighttime ionospheric photometer Far Ultraviolet Nighttime Ionopsheric Photometer (FNIP) is a newly-designed instrument for low earth orbit missions, observing the earth night airglow nadir at OI 135.6\ nm emission produced by ionospheric O++e recombination and receiving the horizontal information on nighttime ionosphere with a spatial resolution of about 1.6o\texttimes3.8o. This simple, highly robust instrument excludes OI 130.4 nm emission and Herzberg oxygen bands with lower power and approximately achieves a sensitivity of about 400\ counts/s/Rayleigh at 135.6\ nm with stray light less than\ 2\ \%. Some tests of the instrument have been conducted and the results will be discussed in the end. Fu, Liping; Peng, Ruyi; Shi, Entao; Peng, Jilong; Wang, Tianfang; Jiang, Fang; Jia, Nan; Li, Xiaoyin; Wang, YongMei; Published by: Astrophysics and Space Science Published on: 01/2015 YEAR: 2015 DOI: 10.1007/s10509-014-2139-9 F2 electron density distribution; FUV optical sensing remote; High sensitivity; Ionosphere; Payload |
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Latitudinal and Solar Cycle Variability of Thermosphere Composition at the Solstices Qian, Liying; Burns, Alan; Wang, Wenbin; Solomon, Stanley; Zhang, Yongliang; Published by: Published on: |
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The Earth’s ionosphere is a magnetoionic medium imbedded in a background neutral atmosphere, exhibiting very interesting refractive properties, including anisotropy, dispersion, and Belehaki, Anna; Tsagouri, Ioanna; Kutiev, Ivan; Marinov, Pencho; Zolesi, Bruno; Pietrella, Marco; Themelis, Kostas; Elias, Panagiotis; Tziotziou, Kostas; Published by: Published on: YEAR: 2015 DOI: "10.1051/swsc/2015026" |
| 2014 |
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A study of GPS ionospheric scintillations observed at Shenzhen Ionospheric scintillation variations are studied using GPS measurements at the low latitude station of Shenzhen (22.59\textdegreeN,\ 113.97\textdegreeE), situated under the northern crest of the equatorial anomaly region, from the Chinese Meridian Project. The results are presented for data collected during the current phase of rising solar activity (low to high solar activity) from December 2010 to April 2014. The results show that GPS scintillation events were largely a nighttime phenomenon during the whole observation period. Scintillation events mainly occurred along the inner edge of the northern crest of the equatorial anomaly in China. The occurrence of scintillations in different sectors of the sky was also investigated, and the results revealed that it is more likely for the scintillations to be observed in the west sector of the sky above Shenzhen. During the present period of study, a total number of 512 total electron content (TEC) depletions and 460 lock loss events were observed. In addition, both of these events are likely to increase during periods of high solar activity, especially because the strong scintillations are often simultaneously accompanied by TEC depletions and lock losses by GPS receivers. Huang, Linfeng; Wang, Jinsong; Jiang, Yong; Chen, Zhou; Zhao, Kai; Published by: Advances in Space Research Published on: 12/2014 YEAR: 2014 DOI: 10.1016/j.asr.2014.08.023 |
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Limb Viewing Hyper Spectral Imager (LiVHySI) for airglow measurements onboard YOUTHSAT-1 Bisht, R.S.; Hait, A.K.; Babu, P.N.; Sarkar, S.S.; Benerji, A.; Biswas, A.; Saji, A.K.; Samudraiah, D.R.M.; Kirankumar, A.S.; Pant, T.K.; Parimalarangan, T.; Published by: Advances in Space Research Published on: 08/2014 YEAR: 2014 DOI: 10.1016/j.asr.2014.01.016 airglow; Electron density; Ionosphere; Rayleigh; thermosphere; Volume emission |
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Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity and solar EUV radiation have been investigated using neutral temperature data observed by the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) instrument and numerical experiments by the NCAR-TIME-GCM (National Center for Atmospheric Research\textendashthermosphere-ionosphere-mesosphere electrodynamics\textendashgeneral circulation model). The TIMED/SABER data analyzed were for the period from 2002 to 2007 during the declining phase of solar cycle 23. The observations show that the zonal mean temperature in the lower thermosphere oscillated with periods of near 9 and 13.5 days in the height range of 100\textendash120 km. These oscillations were more strongly correlated with the recurrent geomagnetic activity than with the solar EUV variability of the same periods. The 9 day and 13.5 day oscillations of lower thermospheric temperature had greater amplitudes at high latitudes than at low latitudes; they also had larger amplitudes at higher altitudes, and the oscillations could penetrate down to ~105 km, depending on the strength of the recurrent geomagnetic activity for a particular time period. The data further show that the periodic responses of the lower thermospheric temperature to recurrent geomagnetic activity were different in the two hemispheres. In addition, numerical experiments have been carried out using the NCAR-TIME-GCM to investigate the causal relationship between the temperature oscillations and the geomagnetic activity and solar EUV variations of the same periods. Model simulations showed the same periodic oscillations as those seen in the observations when the real geomagnetic activity index, Kp, was used to drive the model. These numerical results show that recurrent geomagnetic activity is the main cause of the 9 day and 13.5 day variations in the lower thermosphere temperature, and the contribution from solar EUV variations is minor. Furthermore, we also found that consecutive coronal mass ejection events could cause long-duration enhancements in the lower thermospheric temperature that strengthen the 9 day and 13.5 day signals, and this kind of phenomenon mostly occurred between 2002 and 2005 during the declining phase of solar cycle 23. Jiang, Guoying; Wang, Wenbin; Xu, JiYao; Yue, Jia; Burns, Alan; Lei, Jiuhou; Mlynczak, Martin; Rusell, James; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.610.1002/2013JA019406 13.5 day variation; 9 day variation; Joule heating; lower thermospheric temperature; recurrent geomagnetic activity; solar EUV radiation |
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On the solar cycle variation of the winter anomaly Constellation Observing System for Meteorology, Ionosphere and Climate, Ionosonde, and Global Ultraviolet Imager data have been used to investigate the solar cycle changes in the winter anomaly (the winter anomaly is defined as the enhancement of the F2 peak electron density in the winter hemisphere over that in the summer hemisphere) in the last solar cycle. There is no winter anomaly in solar minimum, and an enhancement of about 50\% in winter over summer ones on the same day of the year at solar maximum. This solar cycle variation in the winter anomaly is primarily due to greater winter to summer differences of [O]/[N2] in solar maximum than in solar minimum, with a secondary contribution from the effects of temperature on the recombination coefficient between O+ and the molecular neutral gas. The greater winter increases in electron density in the Northern Hemisphere than in the Southern Hemisphere appear to be related to the greater annual variation of [O]/[N2] in the north than in the south. Burns, A.; Wang, W.; Qian, L.; Solomon, S.; Zhang, Y.; Paxton, L.; Yue, X.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.610.1002/2013JA019552 |
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Burns, Erick; Williams, Colin; Ingebritsen, Steve; Voss, Clifford; Spane, Frank; DeAngelo, Jake; Published by: Published on: |
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Composition and the Winter Anomaly Burns, Alan; Wang, Wenbin; Qian, Liying; Solomon, Stanley; Zhang, Yongliang; Paxton, Larry; Thayer, Jeffrey; Published by: Published on: |
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Hunton, Don; Pilinski, Marcin; Crowley, Geoff; Azeem, I; Fuller-Rowell, Timothy; Matsuo, Tomoko; Fedrizzi, Mariangel; Solomon, Stanley; Qian, Liying; Thayer, Jeffrey; , others; Published by: Published on: |
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Energetics and Composition in the Thermosphere Burns, AG; Wang, W; Solomon, SC; Qian, L; Published by: Modeling the Ionosphere-Thermosphere System Published on: |
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Ionospheric imaging using merged ultraviolet airglow and radio occultation data The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) and GPS Radio Occultation and Ultraviolet Photometry-Colocated (GROUP-C) experiments are being considered for flight aboard the Space Test Program Houston 5 (STP-H5) experiment pallet to the International Space Station (ISS). LITES is a compact imaging spectrograph that makes one-dimensional images of atmospheric and ionospheric ultraviolet (60-140 nm) airglow above the limb of the Earth. The LITES optical design is advantageous in that it uses a toroidal grating as its lone optical surface to create these high-sensitivity images without the need for any moving parts. GROUP-C consists of two instruments: a nadir-viewing ultraviolet photometer that measures nighttime ionospheric airglow at 135.6 nm with unprecedented sensitivity, and a GPS receiver that measures ionospheric electron content and scintillation with the assistance of a novel antenna array designed for multipath mitigation. By flying together, these two experiments form an ionospheric observatory aboard the ISS that will provide new capability to study low- and mid-latitude ionospheric structures on a global scale. This paper presents the design and implementation of the LITES and GROUP-C experiments on the STP-H5 payload that will combine for the first time high-sensitivity in-track photometry with vertical spectrographic imagery of ionospheric airglow to create high-fidelity images of ionospheric structures. The addition of the GPS radio occultation measurement provides the unique opportunity to constrain, as well as cross-validate, the merged airglow measurements. \textcopyright (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only. Stephan, Andrew; Budzien, Scott; Finn, Susanna; Cook, Timothy; Chakrabarti, Supriya; Powell, Steven; Psiaki, Mark; Published by: Published on: YEAR: 2014 DOI: 10.1117/12.2061420 |
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Configuration of the local interstellar magnetic field Frisch, Priscilla; Andersson, B; Berdhyugin, A; Funsten, HO; DeMajistre, R; Magalhaes, A; McComas, D; , Piirola; Schwadron, N; Seriacopi, D; , others; Published by: Published on: |
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FUSION++: A New Data Assimilative Model for Electron Density Forecasting Bust, Gary; Comberiate, Joseph; Paxton, Larry; Kelly, Mike; Datta-Barua, Seebany; 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: |
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Solomentsev, Dmitry; Cherniak, Yakov; Vyacheslav, Khattatov; Titov, Anton; Khattatov, Boris; Published by: 40th COSPAR Scientific Assembly Published on: |
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The NCAR TIE-GCM: A community model of the coupled thermosphere/ionosphere system Qian, Liying; Burns, Alan; Emery, Barbara; Foster, Benjamin; Lu, Gang; Maute, Astrid; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Wang, Wenbin; Published by: Modeling the Ionosphere-Thermosphere System Published on: |
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Operational Space Weather Needs-Perspectives from SEASONS 2014 Comberiate, Joseph; Kelly, MA; Paxton, Larry; Schaefer, Robert; Bust, Gary; Sotirelis, Thomas; Fox, Nicola; Published by: Published on: |
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A Method to Calculate the Ionospheric LBH Dayglow Emissions for Large Field of View Yong-Chao, ZHANG; Fei, HE; Xiao-Xin, ZHANG; Bo, CHEN; Published by: Chinese Journal of Geophysics Published on: |
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Progress toward forecasting of space weather effects on UHF SATCOM after Operation Anaconda Kelly, Michael; Comberiate, Joseph; Miller, Ethan; Paxton, Larry; Published by: Space Weather Published on: |
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Schaefer, Robert; Paxton, Larry; Romeo, Giuseppe; Wolven, Brian; Zhang, Yongliang; Comberiate, Joseph; Published by: Published on: |
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System and method for tomographic retrieval of parameter profile from traveling path Paxton, Larry; Comberiate, Joseph; Kelly, Michael; Published by: Published on: 11 |
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The anomalous ionosphere between solar cycles 23 and 24 The solar minimum period during 2008\textendash2009 was characterized by lower thermospheric density than the previous solar minimum and lower than any previously measured. Recent work used the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model to show that the primary cause of density changes from 1996 to 2008 was a small reduction in solar extreme ultraviolet (EUV) irradiance, causing a decrease in thermospheric temperature and hence a contracted thermosphere. There are similar effects in the ionosphere, with most measurements showing an F region ionosphere that is unusually low in density, and in peak altitude. This paper addresses the question of whether model simulations previously conducted, and their solar, geomagnetic, and anthropogenic inputs, produce ionospheric changes commensurate with observations. We conducted a 15 year model run and obtained good agreement with observations of the global mean thermospheric density at 400 km throughout the solar cycle, with a reduction of ~30\% from the 1996 solar minimum to 2008\textendash2009. We then compared ionosonde measurements of the midday peak density of the ionospheric F region (NmF2) to the model simulations at various locations. Reasonable agreement was obtained between measurements and the model, supporting the validity of the neutral density comparisons. The global average NmF2 was estimated to have declined between the two solar minima by ~15\%. In these simulations, a 10\% reduction of solar EUV plays the largest role in causing the ionospheric change, with a minor contribution from lower geomagnetic activity and a very small additional effect from anthropogenic increase in CO2. Solomon, Stanley; Qian, Liying; Burns, Alan; Published by: Journal of Geophysical Research: Space Physics Published on: 10/2013 YEAR: 2013 DOI: 10.1002/jgra.v118.1010.1002/jgra.50561 climate; Ionosphere; irradiance; solar; thermosphere; ultraviolet |