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Found 137 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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An extensive intercomparison of ionospheric foF2 observations and NCAR Thermosphere-Ionosphere ElectrodynamicsGeneral Circulation Model(TIE-GCM)simulations has been carried out for the dip equatorial location of Thiruvananthapuram. Ionosonde measurements for geomagnetically quiet days of 2002, 2006 and 2008, representing solar maximum, solar minimum and deep solar minimum conditions have been used for the analysis. In general TIE-GCM simulations reproduced the temporal and seasonal characteristics of foF2 over Thiruvananthapuram reasonably well for all the three solar activity conditions. Seasonally the difference between the measured and the simulated foF2 tended to be higher during winter (maximum of 25\%). Additionally, it is found that TIE-GCM is not reproducing the reduction in the foF2 values in the noon hours i.e. the bite out, which is very prominent in the foF2 observations predominantly during 2002. A detailed analysis revealed that, there is good agreement between the modeled and measured values for the whole observation period, with an R value of 0.81. From the comparison it is clear that the model underestimates the observations in general but for the periods when bite out is prominent, the model gives an over estimation. The comprehensive comparisons during different solar activity conditions have shown that the difference between modeled and measured ionospheric peak densities lies in the range of. 10 to −25\%. This study brings out the efficacy of the model in simulating the temporal seasonal and solar cycle variability of ionospheric foF2 over the equatorial Indian region. Mridula, N.; Manju, G.; Sijikumar, S.; Pant, Tarun; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.018 |
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Far-ultraviolet airglow remote sensing measurements on Feng Yun 3-D meteorological satellite \textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater The Ionospheric Photometer (IPM) is carried on the Feng Yun 3-D (FY3D) meteorological satellite, which allows for the measurement of far-ultraviolet (FUV) airglow radiation in the thermosphere. IPM is a compact and high-sensitivity nadir-viewing FUV remote sensing instrument. It monitors 135.6 nm emission in the nightside thermosphere and 135.6 nm and N\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater Lyman–Birge–Hopfield (LBH) emissions in the dayside thermosphere that can be used to invert the peak electron density of the F\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater layer (NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$)\textless/span\textgreater at night and the \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="73a3f14187048fa14eee70dd1027ad23"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00001.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00001.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater ratio in the daytime, respectively. Preliminary observations show that the IPM could monitor the global structure of the equatorial ionization anomaly (EIA) structure around 02:00 LT using atomic oxygen (OI) 135.6 nm nightglow. It could also identify the reduction of \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="http://www.w3.org/2000/svg" width="25pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7662cd64e23809d534f2b5721e55261b"\textgreater\textlesssvg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-1577-2022-ie00002.svg" width="25pt" height="14pt" src="amt-15-1577-2022-ie00002.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater in the high-latitude region during the geomagnetic storm of 26 August 2018. The IPM-derived NmF\textlessspan class="inline-formula"\textgreater$_\textrm2$\textless/span\textgreater agrees well with that observed by four ionosonde stations along 120\textlessspan class="inline-formula"\textgreater$^\textrm∘$\textless/span\textgreater E with a standard deviation of 26.67 \%. Initial results demonstrate that the performance of IPM meets the design requirements and therefore can be used to study the thermosphere and ionosphere in the future.\textless/p\textgreater Wang, Yungang; Fu, Liping; Jiang, Fang; Hu, Xiuqing; Liu, Chengbao; Zhang, Xiaoxin; Li, JiaWei; Ren, Zhipeng; He, Fei; Sun, Lingfeng; Sun, Ling; Yang, Zhongdong; Zhang, Peng; Wang, Jingsong; Mao, Tian; Published by: Atmospheric Measurement Techniques Published on: mar YEAR: 2022 DOI: 10.5194/amt-15-1577-2022 |
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The ionosphere around the Equatorial Ionization Anomaly (EIA) region exhibits complex dynamics and responds markedly to the solar-magnetospheric energy and momentum. In this paper, the hourly total electron content (TEC) variations in response to the EIA structure in Africa to the 2013 and 2015 St. Patrick’s Day storms is investigated using data obtained from a chain of GPS receivers located in the Africa region. The TEC variations are characterized based on the convective magnetospheric dynamo fields, neutral wind circulation, and zonal electric fields. Generally, the result indicates that the TEC variations are consistent with the different directions of the interplanetary fields during the different phases of the storms. We observed reverse EIA structures in the main phase of the March 2015 storm, likely to be related to the intense PPEF and strong equatorward wind, which imposed a westward zonal electric field at the equator. A similar equatorial peak observed during the recovery phase is associated with DDEF, poleward wind and plasma convergence. Furthermore, the TEC variations also indicate hemispheric asymmetries during the storms. During the main phase of the storm, the TEC variation is more enhanced in the Northern Hemisphere in March 2013 and reverses during March 2015. We observed an equatorial peak during the SSC period in March 2013, while EIA structures are generally weak in March 2015 event. This posit that ionospheric pre-storm behaviour in the EIA region can be better understood when the IMF-Bz and E-field are not significant. The observed distinctive response avowed the peculiarity of the electrodynamics intricacy in the Africa sector. Bolaji, Olawale; Adekoya, Bolarinwa; Adebiyi, Shola; Adebesin, Babatunde; Ikubanni, Stephen; Published by: Astrophysics and Space Science Published on: jan YEAR: 2022 DOI: 10.1007/s10509-021-04022-5 |
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During the sudden stratospheric warming (SSW) event in 2013, we investigated the American low latitude around 75°W. We used 12 Global Positioning System (GPS) receivers, a pair of magnetometers, and the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite airglow instrument to unveil the total electron content (TEC), inferred vertical drift, and the changes in the neutral composition, respectively. A major SSW characterized the 2013 SSW event with the main phase (7–27 January 2013) overlapped by a minor geomagnetic storm (17 January 2013). The late morning inferred downward-directed E X B drift did not support the varying equatorial ionization anomaly (EIA) signature during the SSW onset (7 January 2013). The mid-January (15–16 January 2013) witnessed enhancement in the varying inferred upward-directed E X B drift at both hemispheres. On 17 January 2013, there were reductions in the varying inferred upward-directed E X B drift at both hemispheres. Generally, the SSW effect on TEC around 15–16 January 2013 is more pronounced than the SSW onset. During the mid-January (15–16 January 2013), the higher northern EIA crests are facilitated majorly by the SSW compared to the photo-ionization that primarily enabled the southern crests. On 17 January 2013, the combined effect of photo-ionization and SSW contribution was majorly responsible for the slight reduction in the northern crest. In the southern hemisphere, photo-ionization played the lead role as the SSW, and the minor geomagnetic storm roles are secondary in enhancing the southern crest. Fashae, J.; Bolaji, O.; Rabiu, A.; Published by: Space Weather Published on: YEAR: 2022 DOI: 10.1029/2021SW002999 equatorial ionization anomaly (EIA); geomagnetic storm; low-latitude ionosphere; sudden stratospheric wind (SSW) |
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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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\textlessp\textgreaterTopside ionospheric background distribution and its seasonal variations over China and its adjacent areas, e.g. 0°-54°N and 70°-140°E, are studied using the in situ electron density (Ne) measurements obtained by the LAP payload on board the ZH-1 (CSES) satellite. Results are as followings:(1) Regularities consistent with results from previous studies are shown on the latitudinal extension, longitudinal distribution, and seasonal variations of the EIA (Equatorial Ionization Anomaly) phenomenon in the study area. (2) In the mid-latitude regions, there is a relative low-value zone for the daytime Ne, which shows relative high-value data during nighttime. Nighttime Ne enhancement is shown in all the mid-latitudes for all the seasons when comparing the nighttime and daytime Ne together. The equatorward extension of this phenomenon is in contrast to the poleward extension of the EIA phenomenon; when this phenomenon extends, the EIA shrinks, and vice versa. (3) For the daytime Ne, semiannual anomaly demonstrates a regular pattern, in which the two peaks start in spring and autumn equinoxes at the Equator, then evolve toward the summer solstice with increasing latitude, and finally combine into one summer time peak in mid-latitudes; seasonal anomaly only appears within latitude 4° of the Equator. While for the nighttime Ne, semiannual anomaly appears between latitude 22° and 50°, and seasonal anomaly appears below latitude 22°. (4) The monthly average background of the ionosphere generally shows that the nighttime Ne varies more dramatically than the daytime Ne. For the daytime Ne, observations in both equinoxes and summer solstice vary more violently than that in winter solstice, and observations in EIA regions vary more violently than that in mid-latitude regions. And for the nighttime Ne, observation variations are roughly similar in all seasons and latitudes. (5) Features of the ionospheric background, which fluctuates with time and space in the study area, are relatively complicated, therefore it is necessary to pay attention to the ionosphere background and its fluctuations when conducting studies on ionosphere related scientific problems. Based on the above results and comparisons with other simultaneous observations, we believe that the relative variations of the in situ Ne measurements from the ZH-1 satellite are in consistent with that from other datasets. Besides the well-known ionosphere features, some features which were not found in previous studies are found from the ionosphere background in the study area. The in situ Ne measurements from the ZH-1 satellite are a good data source for systematic studies on ionosphere-related scientific problems due to the similar local times and locations of the observations.\textless/p\textgreater XiuYing, Wang; DeHe, Yang; ZiHan, Zhou; Jing, C.; Na, Zhou; XuHui, Shen; Published by: Chinese Journal of Geophysics Published on: feb YEAR: 2021 DOI: 10.6038/cjg2021O0152 |
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The low-density cell structure in the high-latitude thermosphere is referred to as the density depletion with respect to the adjacent area. Based on Gravity Recovery and Climate Experiment (GRACE) accelerometer data during the September 2017 geomagnetic storms, the thermospheric mass density at about 350 km are estimated and further investigated especially in the high-latitude regions. At least two kinds of low-density cells over the Southern Hemisphere (SH) are observed along the GRACE orbit. To understand the low-density cell structures over the SH observed by GRACE, we investigate the underlying physical mechanism based on thermosphere-ionosphere numerical simulations using Thermosphere-Ionosphere Electrodynamic General Circulation Model and Global Ionosphere Thermosphere Model. According to the simulation results, the formation mechanism of the low-density cell is attributed to the storm-time vertical advection and horizontal velocity divergence driven by the auroral ion convection. The critical height of observable low-density cells is shown to be not less than 350 km. The meridional spatial scale of observed low-density cells over the SH are approximately or slightly larger than 1,500 km. Three low-density cells, including two in the dawn sector and one in the night sector were observed about 1 hour after the direction of interplanetary magnetic field BY component reversed. The occurrence of thermospheric low-density structure is essential to be included in the empirical model during geomagnetic storm time. Yuan, Liangliang; Jin, Shuanggen; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028915 |
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On the dayside of August 25–26, 2018 (main phase, MP of the storm), we unveiled the storm time effects on the latitudinal distribution of ionospheric total electron content (TEC). We used 17 and 19 Global Positioning System receivers in American and Asian-Australian sectors, respectively. Also, we employed a pair of magnetometers in each sector to unveil storm time effects on vertical E × B upward directed inferred drift velocity in the F region ionosphere. Also used is NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite airglow instrument to investigate storm time changes in neutral composition, O/N2 ratio. In this investigation, we corrected the latitudinal offset found in the works of Younas et al. (2020, https://doi.org/10.1029/2020JA027981). Interestingly, we observed that a double-humped increase (DHI) seen at a middle latitude station (MGUE, ∼22°S) after the MP on the dayside in American sector (Younas et al., 2020, https://doi.org/10.1029/2020JA027981) did straddle ∼23.58°N and ∼22°S. On August 25, 2018, storm commencement was evident in Sym-H (∼−8 nT) around 18:00 UT. It later became intensified (∼−174 nT) on August 26 around 08:00 UT. During storm s MP (after the MP), fountain effect operation was significantly enhanced (inhibited) in Asian-Australian (American) sector. Middle latitude TEC during MP got reduced in American sector (13:00 LT–15:40 LT) compared to those seen in Asian-Australian sector (13:00 LT–15:40 LT). The northern equatorial peak (∼25 TECU) seen at IHYO (14:00 LT) after MP in the American sector is higher when compared with that (∼21 TECU) seen at PPPC (11:40 LT) during MP in Asian-Australian sector. Bolaji, O.; Fashae, J.; Adebiyi, S.; Owolabi, Charles; Adebesin, B.; Kaka, R.; Ibanga, Jewel; Abass, M.; Akinola, O.; Adekoya, B.; Younas, W.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA029068 double-humped increase (DHI); equatorial ionization anomaly (EIA); prompt penetrating electric field (PPEF); storm time equatorward wind |
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Inhibition of F3 Layer at Low Latitude Station Sanya During Recovery Phase of Geomagnetic Storms A special F2 layer stratification structure named F3 layer occurs frequently in equatorial and low latitude ionosphere during summer daytime. In this study, a new phenomenon of decreasing occurrence of the F3 layer, and narrowing differences of virtual heights between the F3 and F2 layers in the recovery phase of geomagnetic storms is reported. We named this phenomenon as the inhibition of F3 layer event (IFLE). Using the ionosonde observations during summer of 2012–2015 at Sanya (18.3°N, 109.6°E, dip latitude 12.6°N), we found that IFLE occurred during 14 geomagnetic storms (−127 nT ≤ Dstmin ≤ −22 nT), which was accompanied by the thinning and lowering bottom ionosphere, and decreasing the crest-to-trough ratio of total electron content (TEC). Together with the ion drift data measured by Defense Meteorological Satellite Program F18, we suggest that the IFLE is mainly caused by the westward disturbance dynamo electric field (DDEF; downward drift velocity), taking disadvantage of the formation of the F3 layer. The observed decrease in the crest-to-trough ratio of TEC also indicates that the westward DDEF should prompt IFLE by providing less plasma from the equatorial region to the low latitude. Hence, IFLE then can be a good indicator to show how the magnetosphere-ionospheric coupling process affects the low and equatorial ionosphere. Notably, the results also indicate that even a very weak geomagnetic storm can generate significant changes in ionospheric state at low latitude. Jin, Yuyan; Zhao, Biqiang; Li, Guozhu; Li, Zishen; Zhou, Xu; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029850 F3 layer; Geomagnetic storms; westward disturbance dynamo electric field |
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We present new measurements of the vertical density profile of the Earth s atmosphere at altitudes between 70 and 200 km, based on Earth occultations of the Crab Nebula observed with the X-ray Imaging Spectrometer onboard Suzaku and the hard X-ray Imager onboard Hitomi. X-ray spectral variation due to the atmospheric absorption is used to derive tangential column densities of the absorbing species, that is, N and O including atoms and molecules, along the line of sight. The tangential column densities are then inverted to obtain the atmospheric number density. The data from 219 occultation scans at low latitudes in both hemispheres from September 15, 2005 to March 26, 2016 are analyzed to generate a single, highly averaged (in both space and time) vertical density profile. The density profile is in good agreement with the Naval-Research-Laboratory s-Mass-Spectrometer-Incoherent-Scatter-Radar-Extended (NRLMSISE-00) model, except for the altitude range of 70–110 km, where the measured density is ∼50\% smaller than the model. Such a deviation is consistent with the recent measurement with the SABER aboard the TIMED satellite (Cheng et al., 2020, https://doi.org/10.3390/atmos11040341). Given that the NRLMSISE-00 model was constructed some time ago, the density decline could be due to the radiative cooling/contracting of the upper atmosphere as a result of greenhouse warming in the troposphere. However, we cannot rule out a possibility that the NRL model is simply imperfect in this region. We also present future prospects for the upcoming Japan-US X-ray astronomy satellite, X-Ray Imaging and Spectroscopy Mission (XRISM), which will allow us to measure atmospheric composition with unprecedented spectral resolution of ΔE ∼ 5 eV in 0.3–12 keV. Katsuda, Satoru; Fujiwara, Hitoshi; Ishisaki, Yoshitaka; Yoshitomo, Maeda; Mori, Koji; Motizuki, Yuko; Sato, Kosuke; Tashiro, Makoto; Terada, Yukikatsu; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028886 Crab Nebula; Hitomi; occultation; Suzaku; upper atmosphere; X-rays |
| 2020 |
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The day-glow data application of FY-3D IPM in monitoring O/N2 The Ionosphere Photometer (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite FY-3D, which was Jiang, Fang; Mao, Tian; Zhang, Xiaoxin; Wang, Yungang; Fu, Liping; Hu, Xiuqing; Wang, DaXin; Jia, Nan; Wang, Tianfang; Sun, YueQiang; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2020 DOI: 10.1016/j.jastp.2020.105309 |
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The day-glow data application of FY-3D IPM in monitoring O/N2 The Ionosphere Photometer (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite FY-3D, which was Jiang, Fang; Mao, Tian; Zhang, Xiaoxin; Wang, Yungang; Fu, Liping; Hu, Xiuqing; Wang, DaXin; Jia, Nan; Wang, Tianfang; Sun, YueQiang; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2020 DOI: 10.1016/j.jastp.2020.105309 |
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Global navigation satellite system (GNSS) precise positioning performance will be strongly affected under severe ionospheric anomaly conditions. The combination of multi-GNSS can increase the available observations and improve the geometry of continuously tracked satellites. This paper focuses on assessing the positioning performance with the combination of Global Positioning System (GPS), Global naya Navigatsionnaya Sputnikova Sistema (GLONASS), and BeiDou System (BDS) around the St. Patrick s Day geomagnetic storm (9–18 March) in 2015 in Hong Kong. The rate of total electron content (TEC) index (ROTI) indicates severe ionospheric anomalies before the superstorm, while it was absent during the main phase of the storm in Hong Kong. Furthermore, strong scintillation events on signal-to-noise ratio (SNR) and multipath (MP) observables are observed during ionospheric anomalies period. Then the performance of single-point positioning (SPP) and precise point positioning (PPP) with multi-GNSS is shown. The ionospheric scintillation events may reduce pseudorange accuracy but affect SPP performance a little in this study, while the PPP accuracy is vastly decreased due to the subsequent reconvergence caused by frequent cycle slip (CS). Compared to PPP solutions with GPS only, the accuracy is improved significantly with the combination of multi-GNSS. Lu, Yangwei; Wang, Zhenjie; Ji, Shengyue; Chen, Wu; Published by: Radio Science Published on: YEAR: 2020 DOI: 10.1029/2019RS007004 |
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The Ionosphere PhotoMeter (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite Feng-Yun 3D (FY-3D), which was launched on November 25th, 2017. Jiang, Fang; Mao, Tian; Zhang, Xiaoxin; Wang, Yun-Gang; Hu, Xiuqing; Wang, DaXin; Jia, Nan; Wang, Tianfang; Sun, YueQiang; Fu, Li-Ping; Published by: Advances in Space Research Published on: YEAR: 2020 DOI: 10.1016/j.asr.2020.07.027 |
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The Ionosphere PhotoMeter (IPM) is a far ultraviolet nadir-viewing photometer that flew aboard the second-generation, polar-orbiting Chinese meteorological satellite Feng-Yun 3D (FY-3D), which was launched on November 25th, 2017. Jiang, Fang; Mao, Tian; Zhang, Xiaoxin; Wang, Yun-Gang; Hu, Xiuqing; Wang, DaXin; Jia, Nan; Wang, Tianfang; Sun, YueQiang; Fu, Li-Ping; Published by: Advances in Space Research Published on: YEAR: 2020 DOI: 10.1016/j.asr.2020.07.027 |
| 2019 |
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Annual and Semiannual Oscillations of Thermospheric Composition in TIMED/GUVI Limb Measurements The Global UltraViolet Imager (GUVI) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite provides a data set of vertical thermospheric composition (O, N2, and O2 densities) and temperature profiles from 2002\textendash2007. Even though GUVI sampling is limited by orbital constraint, we demonstrated that the GUVI data set can be used to derive the altitude profiles of the amplitudes and phases of annual oscillation (AO) and semiannual oscillation (SAO), thereby providing important constraints on models seeking to explain these features. We performed a seasonal and interannual analysis of GUVI limb O, O2, and N2 densities and volume number density ratio O/N2 at constant pressure levels. These daytime observations of O and O/N2 in the lower thermosphere show a strong AO at midlatitudes and a clear SAO at lower latitudes. The global mean GUVI O/N2 number density ratio shows the AO, with slightly larger values in January than in July and a SAO with O/N2 greater during equinoxes than at the solstices. O and N2 densities on fixed pressure levels in the upper thermosphere are anticorrelated with solar extreme ultraviolet flux. On the other hand, O/N2 is smaller during solar minimum and larger during solar maximum. The thermospheric AO and SAO in composition have a constant phase with altitude throughout the thermosphere. Yue, Jia; Jian, Yongxiao; Wang, Wenbin; Meier, R.R.; Burns, Alan; Qian, Liying; Jones, M.; Wu, Dong; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2019 YEAR: 2019 DOI: 10.1029/2019JA026544 |
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Topside ionospheric conditions during the 7—8 September 2017 geomagnetic storm The uplooking total electron contents (TECs) from the GRACE, SWARM-A, TerraSAR-X, and MetOp-A satellites and in situ electron density (Ne) from SWARM-A were utilized to investigate the topside ionospheric conditions during the 7–8 September 2017 geomagnetic storm. The rate of TEC index (ROTI) and rate of density index (RODI), which are derivative indices of TEC and Ne, respectively, were also used to characterize the topside ionospheric irregularities. The main results of this study are as follows: (1) There were significant enhancements seen in the uplooking TEC during the first main phase of the storm. (2) The uplooking TEC did not show unusual enhancement at the morning and evening local times in the Asian-Australian sector during the recovery phase of the storm. (3) Prominent TEC hemispheric asymmetry at the middle and high latitudes was observed at both day and night sectors. (4) Long-duration recovery of topside TEC with respect to the prestorm condition was also detected in this event. (5) Nighttime ROTI enhancements were presented in a wide latitudinal range from the equator to the poles during the main phases of the storm. (6) The ionospheric electric field disturbances associated with IMF-Bz fluctuations probably played a very important role in triggering ionospheric irregularities during the relatively weak geomagnetic activity on 7 September, which implies that ionospheric irregularities do not necessarily occur under the severe geomagnetic conditions only. Jimoh, Oluwaseyi; Lei, Jiuhou; Zhong, Jiahao; Owolabi, Charles; Luan, Xiaoli; Dou, Xiankang; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2019 DOI: 10.1029/2019JA026590 |
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Planetary wave-like oscillations in thermospheric composition Yue, Jia; Lieberman, Ruth; Wang, Wenbin; Jian, Yongxiao; Published by: 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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In this study, multiple data sets from Beidou geostationary orbit satellites total electron contents (TECs), ionosonde, meteor radar, magnetometer, and model simulations have been used to investigate the ionospheric responses in the Asian-Australian sector during the September 2017 geomagnetic storm. It was found that long-duration daytime TEC enhancements that lasted from 7 to 12 September 2017 were observed by the Beidou geostationary orbit satellite constellation. This is a unique event as the prominent TEC enhancements persisted during the storm recovery phase when geomagnetic activity became quiet. The Thermosphere-Ionosphere Electrodynamics Global Circulation Model predicted that the TEC enhancements on 7\textendash9 September were associated with the geomagnetic activity, but it showed significant electron density depletions on 10 and 11 September in contrast to the observed TEC enhancements. Our results suggested that the observed long-duration TEC enhancements from 7 to 12 September are mainly associated with the interplay of ionospheric dynamics and electrodynamics. Nevertheless, the root causes for the observed TEC enhancements seen in the storm recovery phase are unknown and require further observations and model studies. Lei, Jiuhou; Huang, Fuqing; Chen, Xuetao; Zhong, Jiahao; Ren, Dexin; Wang, Wenbin; Yue, Xinan; Luan, Xiaoli; Jia, Mingjiao; Dou, Xiankang; Hu, Lianhuan; Ning, Baiqi; Owolabi, Charles; Chen, Jinsong; Li, Guozhu; Xue, Xianghui; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2018 YEAR: 2018 DOI: 10.1029/2017JA025166 |
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Initial Observations with the Ionospheric Photometer on the Chinese Feng Yun 3D Satellite Mao, Tian; Fu, Liping; Wang, Yungang; Jiang, Fang; Hu, Xiuqing; Zhang, Xiaoxin; Sun, Lingfeng; Published by: Published on: |
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Seasonal Variation Analysis of Thermospheric Composition in TIMED/GUVI Limb Measurements Knowledge of thermospheric variability is essential to the understanding and forecasting of ionospheric behavior and space weather. As well, thermospheric density variability is a vital ingredient for prediction of space objects orbital changes and the lifetime of spacecraft. The Global UltraViolet Imager (GUVI) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite provides the first global dataset of thermosphere composition (O, N2 and O2 densities) and temperature vertical profiles from 2002-2007. Yue, Jia; Meier, Robert; Jian, Yongxiao; Yee, Jeng-Hwa; Wu, Dong; Russell, James; Wang, Wenbin; Burns, Alan; Published by: 2018 Triennial Earth-Sun Summit (TESS Published on: |
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Response of GPS-TEC in the African equatorial region to the two recent St. Patrick s day storms The 2015 St. Patrick’s Day storm is one of the most intense geomagnetic storm in this present solar cycle (SYM-H=-213nT). In this paper, we investigate the response of the African low Ikubanni, SO; Adebiyi, SJ; Adebesin, BO; Dopamu, KO; Joshua, BW; Bolaji, OS; Adekoya, BJ; Published by: International Journal of Civil Engineering and Technology Published on: |
| 2017 |
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The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI [O]/[N2] ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm. Jin, Shuanggen; Jin, Rui; Kutoglu, H.; Published by: Journal of Geodesy Published on: 01/2017 YEAR: 2017 DOI: 10.1007/s00190-016-0988-4 |
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The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI [O]/[N2] ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm. Jin, Shuanggen; Jin, Rui; Kutoglu, H.; Published by: Journal of Geodesy Published on: 01/2017 YEAR: 2017 DOI: 10.1007/s00190-016-0988-4 |
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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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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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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. In the modern warfare, how to detect the threats earlier, prevent and reduce the attack of precision-guided missile has become a new challenge. 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. According to current application demands for solar blind ultraviolet detection and warning, this paper proposes a reconnaissance and early-warning optical system, which covers solar blind ultraviolet (250nm-280nm) and dual field. This structure takes advantage of a narrow field of view and long focal length optical system to achieve the target object detection, uses wide-field and short focal length optical system to achieve early warning of the target object. 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\%. Wang, Wen-cong; Jin, Dong-dong; Shao, Fei; Hu, Hui-jun; Shi, Yu-feng; Song, Juan; Zhang, Yu-tu; Yong, Liu; Published by: Published on: YEAR: 2016 DOI: 10.1117/12.2236440 |
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With the development of modern technology, especially the development of information technology at high speed, the ultraviolet early warning system plays an increasingly important Wang, Wen-cong; Jin, Dong-dong; Shao, Fei; Hu, Hui-jun; Shi, Yu-feng; Song, Juan; Zhang, Yu-tu; Yong, Liu; Published by: Published on: YEAR: 2016 DOI: 10.1117/12.2236440 |
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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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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 |
| 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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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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A new solid-state sodium lidar installed at Ramfjordmoen, Troms\o (69.6\textdegreeN, 19.2\textdegreeE), started observations of neutral temperature together with sodium density in the mesosphere-lower thermosphere (MLT) region on 1 October 2010. The new lidar provided temperature data with a time resolution of 10 min and with good quality between \~80 and \~105 km from October 2010 to March 2011. This paper aims at introducing the new lidar with its observational results obtained over the first 6 months of observations. We succeeded in obtaining neutral temperature and sodium density data of \~255.5 h in total. In order to evaluate our observations, we compared (1) the sodium density with that published in the literature, (2) average temperature and column sodium density data with those obtained with Arctic Lidar Observatory for Middle Atmosphere Research Weber sodium lidar, and (3) the neutral temperature data with those obtained by Sounding of the Atmosphere with Broadband Emission Radiometry/Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. For the night of 5 October 2010, we succeeded in conducting simultaneous observations of the new lidar and the European Incoherent Scatter UHF radar with the tristatic Common Program 1 (CP-1) mode. Comparisons of neutral and ion temperatures showed a good agreement at 104 km between 0050 and 0230 UT on 6 October 2010 when the electric field strength was smaller, while significant deviations (up to \~25 K) are found at 107 km. We evaluated contributions of Joule heating and electron-ion heat exchange, but derived values seem to be underestimated. Nozawa, S.; Kawahara, T.; Saito, N.; Hall, C.; Tsuda, T.; Kawabata, T.; Wada, S.; Brekke, A.; Takahashi, T.; Fujiwara, H.; Ogawa, Y.; Fujii, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013JA019520 |
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A new solid-state sodium lidar installed at Ramfjordmoen, Troms\o (69.6\textdegreeN, 19.2\textdegreeE), started observations of neutral temperature together with sodium density in the mesosphere-lower thermosphere (MLT) region on 1 October 2010. The new lidar provided temperature data with a time resolution of 10 min and with good quality between \~80 and \~105 km from October 2010 to March 2011. This paper aims at introducing the new lidar with its observational results obtained over the first 6 months of observations. We succeeded in obtaining neutral temperature and sodium density data of \~255.5 h in total. In order to evaluate our observations, we compared (1) the sodium density with that published in the literature, (2) average temperature and column sodium density data with those obtained with Arctic Lidar Observatory for Middle Atmosphere Research Weber sodium lidar, and (3) the neutral temperature data with those obtained by Sounding of the Atmosphere with Broadband Emission Radiometry/Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. For the night of 5 October 2010, we succeeded in conducting simultaneous observations of the new lidar and the European Incoherent Scatter UHF radar with the tristatic Common Program 1 (CP-1) mode. Comparisons of neutral and ion temperatures showed a good agreement at 104 km between 0050 and 0230 UT on 6 October 2010 when the electric field strength was smaller, while significant deviations (up to \~25 K) are found at 107 km. We evaluated contributions of Joule heating and electron-ion heat exchange, but derived values seem to be underestimated. Nozawa, S.; Kawahara, T.; Saito, N.; Hall, C.; Tsuda, T.; Kawabata, T.; Wada, S.; Brekke, A.; Takahashi, T.; Fujiwara, H.; Ogawa, Y.; Fujii, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2014 YEAR: 2014 DOI: 10.1002/2013JA019520 |
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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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Ground GNSS Ionosphere Sounding Ionospheric delay will bring errors for GNSS navigation and positioning when the electromagnetic wave signal goes through the earth\textquoterights ionosphere from satellites to receivers. The amount of ionospheric delay of GNSS varies from a few meters to decades of meters, but could reach more than decades of meters during severe ionosphere storms. In contrast, the GNSS ionospheric delay may provide some useful information on the ionosphere, e.g. the total electron content (TEC). In this chapter, the theory and methods of ground-based GNSS ionospheric sounding are introduced, including vertical TEC, differential code biases, 2-D and 3-D ionospheric mapping. In addition, some applications are presented and discussed, e.g., GNSS TEC climatology, solar flare and storms response and co-seismic ionospheric behaviors. Jin, Shuanggen; Cardellach, Estel; Xie, Feiqin; Jin, Shuanggen; Cardellach, Estel; Xie, Feiqin; Published by: Published on: YEAR: 2014 DOI: 10.1007/978-94-007-7482-7_4 |
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Ground GNSS Ionosphere Sounding Ionospheric delay will bring errors for GNSS navigation and positioning when the electromagnetic wave signal goes through the earth\textquoterights ionosphere from satellites to receivers. The amount of ionospheric delay of GNSS varies from a few meters to decades of meters, but could reach more than decades of meters during severe ionosphere storms. In contrast, the GNSS ionospheric delay may provide some useful information on the ionosphere, e.g. the total electron content (TEC). In this chapter, the theory and methods of ground-based GNSS ionospheric sounding are introduced, including vertical TEC, differential code biases, 2-D and 3-D ionospheric mapping. In addition, some applications are presented and discussed, e.g., GNSS TEC climatology, solar flare and storms response and co-seismic ionospheric behaviors. Jin, Shuanggen; Cardellach, Estel; Xie, Feiqin; Jin, Shuanggen; Cardellach, Estel; Xie, Feiqin; Published by: Published on: YEAR: 2014 DOI: 10.1007/978-94-007-7482-7_4 |
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Vervack, Ronald; Yee, Jeng-Hwa; Swartz, William; DeMajistre, Robert; Paxton, Larry; Published by: JOHNS HOPKINS APL TECHNICAL DIGEST Published on: |
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High sensitivity trace gas sensor for planetary atmospheres: miniaturized Mars methane monitor Englert, Christoph; Stevens, Michael; Brown, Charles; Harlander, John; DeMajistre, Robert; Marr, Kenneth; Published by: Journal of Applied Remote Sensing Published on: |
| 2013 |
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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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The quiet nighttime low-latitude ionosphere as observed by TIMED/GUVI In this paper, we examine the nighttime ionosphere climatology structure in the low latitude region and discrepancies between Global Ultraviolet Imager (GUVI) observations and the IRI model predictions using (1) the magnetic zonal mean of electron number density as a function of altitude and magnetic latitude, (2) vertical electron density profiles at various levels of F10.7 index, (3) nighttime descent and magnitude decrease of the ionosphere, (4) point-to-point comparisons of F-peak height (hmF2) and density (NmF2), and (5) the magnetic longitudinal variations of hmF2 and NmF2. The data collected from the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) mission since its launch in December 2001 have provided great opportunities for many scientific investigations of the ionosphere. In this analysis, we investigate the climatology of the nighttime low-latitude ionosphere under low geomagnetic activity (kp\ ⩽\ 4) using the electron density profiles inferred from the airglow measurements obtained by the GUVI aboard the TIMED spacecraft and compared with the results obtained from IRI (International Reference Ionosphere) model-2001. The observed climatology is an essential tool for further understanding the electrodynamics in the low-latitude region and improving the model\textquoterights prediction capability. The time range of the GUVI data used in this study is from 2002 (day 053) to 2006 (day 304), and the IRI model predictions were produced at every GUVI location. The ionosphere observed is generally of greater density than what IRI predicts throughout the night for all four seasons for low and moderate solar activity while the model over-predicts the electron density near the F-region peak at high solar activity before midnight. Observations show that the height of the F-region peak has a steep descent from dusk to midnight and near midnight the height of layer is insensitive to solar conditions, significantly different than what is predicted by IRI. Longitudinal features shown in GUVI data are present in the low-latitude ionosphere after sunset and continue through to midnight after which the low-latitude ionosphere is largely zonally symmetric. Talaat, E.R.; Yee, J.-H.; Hsieh, S.-Y.; Paxton, L.J.; DeMajistre, R.; Christensen, A.B.; Bilitza, D.; Published by: Advances in Space Research Published on: 02/2013 YEAR: 2013 DOI: 10.1016/j.asr.2012.11.012 |
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Zimmerman, MI; Hsieh, SW; Brandt, PC; Vandegriff, JD; Stephens, GK; Toigo, AD; Keika, K; Kusterer, MB; DeMajistre, R; Published by: Published on: |
| 2012 |
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GNSS atmospheric and ionospheric sounding—methods and results However, the O/N2 ratio obtained by the GUVI instrument on board the TIMED satellite doesn’t show significant changes in South Korea where the increased NmF2 was observed Published by: Published on: |
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Romeo, G; Paxton, LJ; Schaefer, RK; DeMajistre, R; Comberiate, J; Hsieh, SW; Miller, ES; Weiss, M; Wolven, BC; Zhang, Y; Published by: Published on: |