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Found 171 entries in the Bibliography.
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| 2022 |
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We propose a new method for retrieving the atmospheric number density profile in the lower thermosphere, based on the X-ray Earth occultation of the Crab Nebula with the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite. The absorption and scattering of X-rays by the atmosphere result in changes in the X-ray energy, and the Earth’s neutral atmospheric number density can be directly retrieved by fitting the observed spectrum and spectrum model at different altitude ranges during the occultation process. The pointing observations from LE/Insight-HXMT on 16 November 2017 are analyzed to obtain high-level data products such as lightcurve, energy spectrum and detector response matrix. The results show that the retrieved results based on the spectrum fitting in the altitude range of 90–200 km are significantly lower than the atmospheric density obtained by the NRLMSISE-00 model, especially in the altitude range of 110–120 km, where the retrieved results are 34.4\% lower than the model values. The atmospheric density retrieved by the new method is qualitatively consistent with previous independent X-ray occultation results (Determan et al., 2007; Katsuda et al., 2021), which are also lower than empirical model predictions. In addition, the accuracy of atmospheric density retrieved results decreases with the increase of altitude in the altitude range of 150–200 km, and the accurate quantitative description will be further analyzed after analyzing a large number of X-ray occultation data in the future. Yu, Daochun; Li, Haitao; Li, Baoquan; Ge, Mingyu; Tuo, Youli; Li, Xiaobo; Xue, Wangchen; Liu, Yaning; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.02.030 Atmospheric density vertical profile; Energy spectrum fitting; X-ray occultation |
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\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater X-ray Earth occultation sounding (XEOS) is an emerging method for measuring the neutral density in the lower thermosphere. In this paper, the X-ray Earth occultation (XEO) of the Crab Nebula is investigated using the Hard X-ray Modulation Telescope (Insight-HXMT). The pointing observation data on the 30 September 2018 recorded by the low-energy X-ray telescope (LE) of Insight-HXMT are selected and analysed. The extinction light curves and spectra during the X-ray Earth occultation process are extracted. A forward model for the XEO light curve is established, and the theoretical observational signal for light curve is predicted. The atmospheric density model is built with a scale factor to the commonly used Mass Spectrometer Incoherent Scatter Radar Extended model (MSIS) density profile within a certain altitude range. A Bayesian data analysis method is developed for the XEO light curve modelling and the atmospheric density retrieval. The posterior probability distribution of the model parameters is derived through the Markov chain–Monte Carlo (MCMC) algorithm with the NRLMSISE-00 model and the NRLMSIS 2.0 model as basis functions, and the respective best-fit density profiles are retrieved. It is found that in the altitude range of 105–200 km, the retrieved density profile is 88.8 \% of the density of NRLMSISE-00 and 109.7 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 1.0–2.5 keV based on the XEOS method. In the altitude range of 95–125 km, the retrieved density profile is 81.0 \% of the density of NRLMSISE-00 and 92.3 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 2.5–6.0 keV based on the XEOS method. In the altitude range of 85–110 km, the retrieved density profile is 87.7 \% of the density of NRLMSISE-00 and 101.4 \% of the density of NRLMSIS 2.0 by fitting the light curve in the energy range of 6.0–10.0 keV based on the XEOS method. Goodness-of-fit testing is carried out for the validation of the results. The measurements of density profiles are compared to the NRLMSISE-00 and NRLMSIS 2.0 model simulations and the previous retrieval results with NASA s Rossi X-ray Timing Explorer (RXTE) satellite. For further confirmation, we also compare the measured density profile to the ones by a standard spectrum retrieval method with an iterative inversion technique. Finally, we find that the retrieved density profile from Insight-HXMT based on the NRLMSISE-00 and NRLMSIS 2.0 models is qualitatively consistent with the previous retrieved results from RXTE. The results of light curve fitting and standard energy spectrum fitting are in good agreement. This research provides a method for the evaluation of the density profiles from MSIS model predictions. This study demonstrates that the XEOS from the X-ray astronomical satellite Insight-HXMT can provide an approach for the study of the upper atmosphere. The Insight-HXMT satellite can join the family of the XEOS. The Insight-HXMT satellite with other X-ray astronomical satellites in orbit can form a space observation network for XEOS in the future.\textless/p\textgreater Yu, Daochun; Li, Haitao; Li, Baoquan; Ge, Mingyu; Tuo, Youli; Li, Xiaobo; Xue, Wangchen; Liu, Yaning; Wang, Aoying; Zhu, Yajun; Luo, Bingxian; Published by: Atmospheric Measurement Techniques Published on: may YEAR: 2022 DOI: 10.5194/amt-15-3141-2022 |
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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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In the White Paper, submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we present the importance of advancing our knowledge of plasma-neutral gas interactions, and of deepening our understanding of the partially ionized environments that are ubiquitous in the upper atmospheres of planets and moons, and elsewhere in space. In future space missions, the above task requires addressing the following fundamental questions: (A) How and by how much do plasma-neutral gas interactions influence the re-distribution of externally provided energy to the composing species? (B) How and by how much do plasma-neutral gas interactions contribute toward the growth of heavy complex molecules and biomolecules? Answering these questions is an absolute prerequisite for addressing the long-standing questions of atmospheric escape, the origin of biomolecules, and their role in the evolution of planets, moons, or comets, under the influence of energy sources in the form of electromagnetic and corpuscular radiation, because low-energy ion-neutral cross-sections in space cannot be reproduced quantitatively in laboratories for conditions of satisfying, particularly, (1) low-temperatures, (2) tenuous or strong gradients or layered media, and (3) in low-gravity plasma. Measurements with a minimum core instrument package (\textless 15 kg) can be used to perform such investigations in many different conditions and should be included in all deep-space missions. These investigations, if specific ranges of background parameters are considered, can also be pursued for Earth, Mars, and Venus. Yamauchi, Masatoshi; De Keyser, Johan; Parks, George; Oyama, Shin-ichiro; Wurz, Peter; Abe, Takumi; Beth, Arnaud; Daglis, Ioannis; Dandouras, Iannis; Dunlop, Malcolm; Henri, Pierre; Ivchenko, Nickolay; Kallio, Esa; Kucharek, Harald; Liu, Yong; Mann, Ingrid; Marghitu, Octav; Nicolaou, Georgios; Rong, Zhaojin; Sakanoi, Takeshi; Saur, Joachim; Shimoyama, Manabu; Taguchi, Satoshi; Tian, Feng; Tsuda, Takuo; Tsurutani, Bruce; Turner, Drew; Ulich, Thomas; Yau, Andrew; Yoshikawa, Ichiro; Published by: Experimental Astronomy Published on: mar YEAR: 2022 DOI: 10.1007/s10686-022-09846-9 Collision cross-section; Future missions; Low-energy; Neutral gas; Plasma; Voyage 2050 |
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Contribution of the lower atmosphere to the day-to-day variation of thermospheric density In this paper we carried out a numerical experiment using the Specified Dynamics mode of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (SD-WACCM-X). One SD-WACCM-X run was with realistic Kp and F10.7 and the other with constant Kp and F10.7. By comparing the day-to-day variability of thermosphere mass density at 300 km (low earth orbit, LEO) and 120 km (reentry level) in these two runs, we find that the density variation at 300 km is mainly driven by geomagnetic and solar forcing while at 120 km it is exclusively controlled by the lower atmosphere. At LEO altitudes, during solar minimum and geomagnetic quiet days, the impact from the lower atmosphere is much smaller than the effect of solar and geomagnetic variations but is not negligible (5–10\% vs 20\%). Yue, Jia; Yu, Wandi; Pedatella, Nick; Bruinsma, Sean; Wang, Ningchao; Liu, Huixin; Published by: Advances in Space Research Published on: jun YEAR: 2022 DOI: 10.1016/j.asr.2022.06.011 |
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Optomechanical design of a wide-field auroral imager on Fengyun-3D We present the optomechanical design and development of a wide-field auroral imager (WAI) on board the satellite Fengyun-3D. The optomechanical system of the WAI features a combination of a large field of view and a single-axis scanning mechanism. The combination makes the WAI perform better than its counterparts in temporal resolution in a low Earth orbit. In-orbit tests have verified the survival of WAI in the launching vibration and space environment. It has functioned on-orbit since 2018, with a spatial resolution of ∼10km at the nadir point, at a reference height of 110 km above the ionosphere. Guo, Quanfeng; Chen, Bo; Liu, ShiJie; Song, KeFei; He, LingPing; He, Fei; Zhao, Weiguo; Wang, Zhongsu; Chen, Liheng; Shi, Guangwei; Published by: Applied Optics Published on: apr YEAR: 2022 DOI: 10.1364/AO.453949 |
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Ionospheric storm enhanced density (SED) has been extensively investigated using total electron content deduced from GPS ground and satellite-borne receivers. However, dayside in situ electron density measurements have not been analyzed in detail for SEDs yet. We report in situ electron density measurements of a SED event in the Northern Hemisphere (NH) at the noon meridian plane measured by the Challenging Minisatellite Payload (CHAMP) polar-orbiting satellite at about 390 km altitude during the 20 November 2003 magnetic storm. The CHAMP satellite measurements render rare documentation about the dayside SED s life cycle at a fixed magnetic local time (MLT) through multiple passes. Solar wind drivers triggered the SED onset and controlled its lifecycle through its growth and retreat phases. The SED electron density enhancement extended from the equatorial ionization anomaly to the noon cusp. The midlatitude electron density increased to a maximum at the end of the growth phase. Afterward, the dayside SED region retreated gradually to lower magnetic latitudes. The observations showed a hemisphere asymmetry, with the NH electron density exhibiting a more significant enhancement. The simulations using the Thermosphere Ionosphere Electrodynamic General Circulation model show a good agreement with the CHAMP observations. The simulations indicate that the dayside midlatitude electron density enhancement has a complicated dependence on vertical ion drift, neutral wind, magnetic latitude, MLT, and the height of the F2 layer. Finally, we discuss the notion of using the mean cross-polar cap electric field as a proxy for assessing the effects of solar wind drivers on producing midlatitude electron density enhancement. Lin, Chin; Sutton, Eric; Wang, Wenbin; Cai, Xuguang; Liu, Guiping; Henney, Carl; Cooke, David; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029831 in situ plasma density; ionospheric electron density; prompt penetration electric field; Storm enhanced density; tongue of ionization |
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We use the in-situ observations of DMSP and SWARM satellites to report the changes of the topside ionospheric electron temperature during the October 2016 storm. Electron temperature in the afternoon sector dramatically increases in low latitudes in the recovery phase of the storm. Furthermore, the temperature enhancements have an obvious dependence on longitude and are mainly centralized around 100°–150°E in different satellite observations. The temperature enhancements attain more than 2,000 K at 840 km and 1,500 K at 450 km around the magnetic equator. The decrease in the electron-ion collision cooling rate, resulting from the lessened topside electron density, could not fully explain the temperature enhancement. At the same time, the electron densities in crests of the equatorial ionization anomaly are suppressed drastically at 100°–150°E, which cause a less heat conduction effect from the equatorial topside ionosphere to low altitudes via magnetic field lines and heat the topside ionospheric electron temperature. Further analysis indicates that dayside westward disturbance dynamo electric field presents a significant longitude structure and is a primary driver for the topside ionospheric temperature enhancement during the storm. Zhang, Ruilong; Liu, Libo; Ma, Han; Chen, Yiding; Le, Huijun; Yoshikawa, Akimasa; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2022JA030278 electron temperature; equatorial topisde; Ionospheric storm; vertical drift |
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By using Wuhan VHF radar, we show the morphological features of E-region field-aligned irregularity (FAI) occurrence at Wuhan during 2015–2020. Statistical results present that E-region FAI occurrence reaches a maximum after sunset in summer season. According to Doppler spectrum features, type-2 irregularity is predominantly observed at Wuhan. In addition, we observed a remarkable correlation between E-region FAI occurrence and geomagnetic activity, which includes periods of positive correlation and negative correlation depending on different geomagnetic conditions. The strong negative correlation also exists between E-region FAI occurrence and solar activity. In our observed results, we find that E-region FAI occurrence shows a strong linkage with local sporadic E (ES) layer. A quantitative analysis of linear theory of plasma instability in the E-region at midlatitudes is also presented in our study. The calculated results of linear growth rate indicate the importance of plasma density gradient of local ES layer and field-line-integrated Pedersen conductivity on the generation of E-region FAI. The geomagnetic and solar variations of E-region FAI occurrence are also discussed in this study, which show a dependence on the geomagnetic and solar variations of both meteor rate and medium-scale traveling ionospheric disturbance occurrence. Liu, Yi; Zhou, Chen; Xu, Tong; Deng, Zhongxin; Du, Zhitao; Lan, Ting; Tang, Qiong; Zhu, Yunzhou; Wang, Zhuangkai; Zhao, Zhengyu; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029597 |
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This paper presents the longitudinal dependence of ionospheric responses from Global Navigation Satellite System (GNSS) derived Total Electron Content (TEC) during two intense geomagnetic storms of May and September 2017. The GNSS-TEC is retrieved from four stations installed at the verge of low to mid-latitude Asian regions of Pakistan and China. Two ionospheric enhancements were observed during the storm of May 2017. The first one at local noon–afternoon during the storm main phase on 28 May was due to the southward turning of Interplanetary Magnetic Field (IMF-Bz) and eastward Prompt Penetration Electric Field (PPEF), with the maximum TEC enhancement at Wuhan. The second one at nighttime during the recovery phase of the storm on 29 May triggered ionospheric variations, mainly due to the later southward turning of the IMF-Bz as the Asian regions, were on the nightside with the westward PPEF. Negative storm time ionospheric responses were observed on 30 May, related to the change of the thermospheric composition as O/N2 depletion. Moreover, a significant increase in TEC was recorded during the main phase of the storm on 8 September 2017. This enhancement corresponded with the eastward PPEF and an increase in the O/N2. The TEC increment was also observed during the recovery phase on 9 September in the Pakistani stations. A minor storm on 7 September also gave rise to TEC enhancements, especially in western regions. However, the negative phase was registered from 9 to 10 September at each station because of the changes in the thermospheric composition as O/N2 depletion. Tariq, Arslan; Yuyan, Yang; Shah, Munawar; Shah, Ali; Iqbal, Talat; Liu, Libo; Published by: Advances in Space Research Published on: YEAR: 2022 DOI: 10.1016/j.asr.2022.08.050 |
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The GUVI measurements indicated that the atomic oxygen (O) to molecular nitrogen (N2) (2021a) used the TIMED/GUVI limb measurements and TIEGCM simulations to investigate Lin, Chin; Sutton, Eric; Wang, Wenbin; Cai, Xuguang; Liu, Guiping; Henney, Carl; Cooke, David; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029831 |
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Retrospect and prospect of ionospheric weather observed by FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2 FORMOSAT-3/COSMIC (F3/C) constellation of six micro-satellites was launched into the circular low-earth orbit at 800 km altitude with a 72-degree inclination angle on 15 April 2006 Liu, Tiger; Lin, Charles; Lin, Chi-Yen; Lee, I-Te; Sun, Yang-Yi; Chen, Shih-Ping; Chang, Fu-Yuan; Rajesh, Panthalingal; Hsu, Chih-Ting; Matsuo, Tomoko; , others; Published by: Terrestrial, Atmospheric and Oceanic Sciences Published on: YEAR: 2022 DOI: 10.1007/s44195-022-00019-x |
| 2021 |
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Recent studies revealed that the long-lasting daytime ionospheric enhancements of Total Electron Content (TEC) were sometimes observed in the Asian sector during the recovery phase of geomagnetic storms (e.g., Lei (J Geophys Res Space Phys 123: 3217–3232, 2018), Li (J Geophys Res Space Phys 125: e2020JA028238, 2020). However, they focused only on the dayside ionosphere, and no dedicated studies have been performed to investigate the nighttime ionospheric behavior during such kinds of storm recovery phases. In this study, we focused on two geomagnetic storms that happened on 7–8 September 2017 and 25–26 August 2018, which showed the prominent daytime TEC enhancements in the Asian sector during their recovery phases, to explore the nighttime large-scale ionospheric responses as well as the small-scale Equatorial Plasma Irregularities (EPIs). It is found that during the September 2017 storm recovery phase, the nighttime ionosphere in the American sector is largely depressed, which is similar to the daytime ionospheric response in the same longitude sector; while in the Asian sector, only a small TEC increase is observed at nighttime, which is much weaker than the prominent daytime TEC enhancement in this longitude sector. During the recovery phase of the August 2018 storm, a slight TEC increase is observed on the night side at all longitudes, which is also weaker than the prominent daytime TEC enhancement. For the small-scale EPIs, they are enhanced and extended to higher latitudes during the main phase of both storms. However, during the recovery phases of the first storm, the EPIs are largely enhanced and suppressed in the Asian and American sectors, respectively, while no prominent nighttime EPIs are observed during the second storm recovery phase. The clear north–south asymmetry of equatorial ionization anomaly crests during the second storm should be responsible for the suppression of EPIs during this storm. In addition, our results also suggest that the dusk side ionospheric response could be affected by the daytime ionospheric plasma density/TEC variations during the recovery phase of geomagnetic storms, which further modulates the vertical plasma drift and plasma gradient. As a result, the growth rate of post-sunset EPIs will be enhanced or inhibited. Wan, Xin; Xiong, Chao; Gao, Shunzu; Huang, Fuqing; Liu, Yiwen; Aa, Ercha; Yin, Fan; Cai, Hongtao; Published by: Satellite Navigation Published on: nov YEAR: 2021 DOI: 10.1186/s43020-021-00055-x Equatorial plasma irregularity; Geomagneitc storm; Ionospheric response; longitudinal variations; Storm recovery phase |
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The Global Positioning System (GPS) cycle slip has a marked impact on the application of communication and navigation systems and therefore is one of the main concerns of the user and designer of terminal systems. In this study, we analyzed the temporal and spatial characteristics of cycle slip events using the GPS data detected from 260 observations in the China sector during the period of the year 2015–2018. The results show that the temporal variations of cycle slips are dependent on the local time, seasons, and solar activity. It occurs from 20:00 LT to midnight and more frequently in the equinox months, especially in solar maximum years. The spatial distribution occurs mainly at southern sector below 25°N, which should be associated with the solar condition and ionospheric irregularities in the equatorial region, and the case analyses reveal that the variation of cycle slips has a similar tendency with the ionospheric scintillation monitored at low-latitude station Guangzhou explaining this relationship. Our results reflect the performance of the GPS signals monitored in the China area during the declining period of solar activity to some degree. Geng, Wei; Huang, Wengeng; Liu, Guoqi; Liu, Siqing; Luo, Binxian; Chen, Yanhong; Published by: Radio Science Published on: may YEAR: 2021 DOI: 10.1029/2020RS007196 Monitoring; Delays; Global positioning system; Indexes; Receivers; Satellite broadcasting; Signal to noise ratio |
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The Global Positioning System (GPS) cycle slip has a marked impact on the application of communication and navigation systems and therefore is one of the main concerns of the user and designer of terminal systems. In this study, we analyzed the temporal and spatial characteristics of cycle slip events using the GPS data detected from 260 observations in the China sector during the period of the year 2015–2018. The results show that the temporal variations of cycle slips are dependent on the local time, seasons, and solar activity. It occurs from 20:00 LT to midnight and more frequently in the equinox months, especially in solar maximum years. The spatial distribution occurs mainly at southern sector below 25°N, which should be associated with the solar condition and ionospheric irregularities in the equatorial region, and the case analyses reveal that the variation of cycle slips has a similar tendency with the ionospheric scintillation monitored at low-latitude station Guangzhou explaining this relationship. Our results reflect the performance of the GPS signals monitored in the China area during the declining period of solar activity to some degree. Geng, Wei; Huang, Wengeng; Liu, Guoqi; Liu, Siqing; Luo, Binxian; Chen, Yanhong; Published by: Radio Science Published on: may YEAR: 2021 DOI: 10.1029/2020RS007196 Monitoring; Delays; Global positioning system; Indexes; Receivers; Satellite broadcasting; Signal to noise ratio |
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By using the data of GNSS (Global Navigation Satellite System) observation from Crustal Movement Observation Network of China (CMONOC), ionospheric electron density (IED) distributions reconstructed by using computerized ionospheric tomography (CIT) technique are used to investigate the ionospheric storm effects over Wuhan region during 17 March and 22 June 2015 geomagnetic storm periods. F-region critical frequency (foF2) at Wuhan ionosonde station shows an obvious decrease during recovery phase of the St. Patrick’s Day geomagnetic storm. Moreover, tomographic results present that the decrease in electron density begins at 12:00 UT on 17 March during the storm main phase. Also, foF2 shows a long-lasting negative storm effect during the recovery phase of the 22 June 2015 geomagnetic storm. Electron density chromatography presents the evident decrease during the storm day in accordance with the ionosonde observation. These ionospheric negative storm effects are probably associated with changes of chemical composition, PPEF and DDEF from high latitudes. Feng, Jian; Zhou, Yufeng; Zhou, Yan; Gao, Shuaihe; Zhou, Chen; Tang, Qiong; Liu, Yi; Published by: Advances in Space Research Published on: jan YEAR: 2021 DOI: 10.1016/j.asr.2020.10.008 Ionospheric electron density distributions; ionospheric storm effects; Multiplication algebraic reconstruction technique |
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Improved model of ionosphere variability and study for long-term statistical characteristics Ionospheric variability is influenced by many factors, such as solar radiation, neutral atmosphere composition, and geomagnetic disturbances. Mainly characterized by the total electron content (TEC) and electron density, the climatology of the ionosphere features temporal and spatial changes. Establishing a multivariant regression model helps substantially in better understanding the ionosphere characteristics and their long-term variability. In this paper, an improvement of the existing ionosphere multivariate linear fitting regression model is proposed and investigated using data from both the ionosonde and the global ionosphere map (GIM) derived from ground-based Global Navigation Satellite System (GNSS) observations. The proposed method gives more consideration to the impact of the solar activity and adds modeling of the annual periodic fluctuations and half-year periodic fluctuations for the F10.7 index. The improved model is verified to have a better correlation with the real observations and can help reduce the calculation uncertainty. Moreover, the proposed model is used to evaluate the fitting accuracy of the GIMs produced by five authorized data analysis centers from the International GNSS Service (IGS). The results show that there is a fixing hole in the North America region for the GIM model where the correlation between the GIM and the proposed model always returns lower values compared to other places. Published by: Chinese Journal of Aeronautics Published on: feb YEAR: 2021 DOI: 10.1016/j.cja.2020.03.018 total electron content; Analysis of anomalies; Long-term statistics; Regression model |
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Hemispheric asymmetries of the Vertical Total Electron Content (VTEC) were observed during the first recovery phase of the geomagnetic storm on September 7–8, 2017. These asymmetries occurred at the mid latitudes at two different local times simultaneously: In the European-African sector (early morning), the storm time VTEC in the southern/northern hemisphere was higher/lower than the quiet time value, suggesting the southern/northern hemisphere entered the positive/negative phase (N−S+). In the East Asian-Australian sector (afternoon), the storm time VTEC change was positive in the northern hemisphere, but negative in the southern hemisphere (N+S−). The electron density profiles from digisondes demonstrated that the asymmetries appeared in the F region density as well. The plasma drifts data from digisondes, the column-integrated [O]/[N2] ratio from GUVI onboard the TIMED satellite, and the detrended VTEC were utilized to study the drivers of the asymmetries. Traveling Ionospheric Disturbance (TID) signatures were identified in the digisonde drift and detrended VTEC data before the appearance of the asymmetry. The magnitude of TIDs was larger in the hemisphere where the negative phase occurred later. The storm time [O]/[N2] ratio change was positive in Africa (S+) and negative in Europe (N−). However, the [O]/[N2] measurements were not available in the East Asian-Australian sector during the focused period. The hemispheric differences in the vertical drifts were also observed in both sectors. Therefore, the observed hemispheric asymmetries in both sectors are suggested to be due to the hemispheric asymmetries in the thermospheric composition change, vertical drift, and TID activity. Wang, Zihan; Zou, Shasha; Liu, Lei; Ren, Jiaen; Aa, Ercha; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028829 |
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Wide-field aurora imager onboard Fengyun satellite: Data products and validation New observations of auroras based on the wide-field aurora imager (WAI) onboard Fengyun-3D (FY-3D) satellite are exhibited in this paper. Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F18). Dynamic variations of the aurora with the solar wind, interplanetary magnetic field (IMF) parameters, and the SYM-H index are also investigated. The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics. Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth s space weather. Since the configuration of aurora is a good indicator of the solar wind-magnetosphere-ionosphere (SW-M-I) coupling system, and can reflect the disturbance of the space environment, the WAI will provide important data to help us to study the physical processes in space. Ding, GuangXing; Li, JiaWei; Zhang, Xiaoxin; He, Fei; He, LingPing; Song, KeFei; Sun, Liang; Dai, Shuang; Liu, ShiJie; Chen, Bo; Yu, Chao; Hu, Xiuqing; Gu, SongYan; Yang, Zhongdong; Zhang, Peng; Published by: Earth and Planetary Physics Published on: YEAR: 2021 DOI: 10.26464/epp2021003 |
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Near Real-Time Global Plasma Irregularity Monitoring by FORMOSAT-7/COSMIC-2 This study presents initial results of the ionospheric scintillation in the F layer using the S4 index derived from the radio occultation experiment (RO-S4) on FORMOSAT-7/COSMIC-2 (F7/C2). With the sufficiently dense RO-S4 observations at low latitudes, it is possible to construct hourly, global scintillation maps to monitor equatorial plasma bubbles (EPBs). The preliminary F7/C2 RO-S4 during August 2019 to April 2020 show clear scintillation distributions around American and the Atlantic Ocean longitudes. The RO-S4 near Jicamarca are compared with range-time-intensity (RTI) maps of the 50 MHz radar, and the results show that the occurrence of intense RO-S4 in the range 0.125–0.5 are co-located with the bottomside of the spread-F patterns. Increases in RO-S4 at the upward phase of bottom-side oscillations is theoretically consistent with large-scale wave seeding of the EPBs. The locations and occurrences of the RO-S4 greater than 0.5 are consistent with airglows depletions from the NASA GOLD mission. Climatology analyses show that monthly occurrences of RO-S4 \textgreater 0.5 agree well with the monthly EPB occurrences in GOLD 135.6 nm image, and show a similar longitudinal distribution to that of DMSP and C/NOFS in-situ measurements. The results suggest that the RO-S4 intensities can be utilized to identify EPBs of specific scales. Chen, Shih-Ping; Lin, Charles; Rajesh, Panthalingal; Liu, Jann-Yenq; Eastes, Richard; Chou, Min-Yang; Choi, Jong-Min; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028339 equatorial plasma bubbles; FORMOSAT-7/COSMIC-2; global observation of limb and disk; GNSS scintillation; radio occultation; S4 index |
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The Ionosphere at Middle and Low Latitudes Under Geomagnetic Quiet Time of December 2019 The ionospheric electron density shows remarkable day-to-day variability due to solar radiance, geomagnetic activity and lower atmosphere forcing. In this report, we investigated the ionospheric variations at middle and low latitudes during a period under geomagnetic quiet time (Kpmax = 1.7) from November 30 to December 8, 2019. During the quiescent period, the ionosphere is not undisturbed as expected in the Asian-Australian and the American sectors. Total electron content (TEC) has multiple prominent enhancements at middle and low latitudes in the two sectors, and TEC depletions also occur repeatedly in the Asian-Australian sector. The low-latitude electric fields vary significantly, which is likely to be modulated by the notably changing tides in the mesosphere and lower thermosphere region. It is worth noting that the variations of TEC and the electric fields are not consistent in the two sectors, particularly on December 4–6. Further investigation reveals that the increase in TEC depends on altitude. The TEC enhancements are mainly contributed by the altitude below 500 km in both two sectors, which indirectly reflects that the driving sources may come from the lower atmosphere. Especially, a mid-latitude band structure continuously appears at all local times in the North American sector on December 6–8, which is also mainly contributed by the altitude below 500 km. Kuai, Jiawei; Li, Qiaoling; Zhong, Jiahao; Zhou, Xu; Liu, Libo; Yoshikawa, Akimasa; Hu, Lianhuan; Xie, Haiyong; Huang, Chaoyan; Yu, Xumin; Wan, Xin; Cui, Jun; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028964 low-latitude electric fields; the ionosphere variations in solar minimum; the ionospheric day-to-day variations; the ionospheric disturbance; the ionospheric variations; topside ionosphere |
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Santa Maria Digisonde data are used for the first time to investigate the F region behavior during a geomagnetic storm. The August 25, 2018 storm is considered complex due to the incidence of two Interplanetary Coronal Mass Ejections and a High-Speed Solar Wind Stream (HSS). The F 2 layer critical frequency (f o F 2) and its peak height (h m F 2) collected over Santa Maria, near the center of the South American Magnetic Anomaly (SAMA), are compared with data collected from Digisondes installed in the Northern (NH) and Southern (SH) Hemispheres in the American sector. The deviation of f o F 2 (Df o F 2) and h m F 2 (Dh m F 2) are used to quantify the ionospheric storm effects. Different F region responses were observed during the main phase (August 25–26), which is attributed to the traveling ionospheric disturbances and disturbed eastward electric field during nighttime. The F region responses became highly asymmetric between the NH and SH at the early recovery phase (RP, August 26) due to a combination of physical mechanisms. The observed asymmetries are interpreted as caused by modifications in the thermospheric composition and a rapid electrodynamic mechanism. The persistent enhanced thermospheric [O]/[N2] ratio observed from August 27 to 29 combined with the increased solar wind speed induced by the HSS and IMF B z fluctuations seem to be effective in causing the positive ionospheric storm effects and the shift of the Equatorial Ionization Anomaly crest to higher than typical latitudes. Consequently, the most dramatic positive ionospheric storm during the RP occurred over Santa Maria (∼120\%). Moro, J.; Xu, J.; Denardini, C.; Resende, L.; Neto, P.; Da Silva, L.; Silva, R.; Chen, S.; Picanço, G.; Carmo, C.; Liu, Z.; Yan, C.; Wang, C.; Schuch, N.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028663 Digisonde; Equatorial ionization anomaly; F-region; Ionospheric storm; SAMA; space weather |
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This study examines an unexpected and extreme positive ionospheric response to a minor magnetic storm on August 5, 2019 by using global ionosphere specification (GIS) 3D electron density profiles obtained by assimilating radio occultation total electron content (TEC) measurements of the recently launched FORMOSAT-7/COSMIC-2 satellites, and ground-based global navigation satellite system (GNSS) TEC. The results reveal ∼300\% enhancement of equatorial ionization anomaly (EIA) crests, appearing over 200–300 km altitudes, and a much intense localized density enhancement over the European sector. These are the most intense ionospheric response that has ever been detected for a small magnetic storm with Dst ∼ −53 nT (SYM-H ∼ −64 nT). The enhancements are validated by using global ionosphere map (GIM) TEC and ground-based GNSS TEC. The GIS vertical electron density structures during the storm are examined to understand the physical processes giving rise to such an intense ionosphere response during deep solar minimum conditions when the background electron density is very low. Altitude variations and poleward shifts of the locations of the EIA crests indicate that prompt penetration electric fields (PPEF) play an important role in producing the observed positive storm responses, with the storm-induced equatorward circulation supporting the plasma accumulation against recombination losses. Additional physical mechanisms are required to fully explain the unexpected electron density enhancements for this minor storm event. Rajesh, P.; Lin, C.; . Y. Lin, C; Chen, C.; . Y. Liu, J; Matsuo, T.; Chen, S.; Yeh, W.; . Y. Huang, C; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028261 FORMOSAT-7/COSMIC-2; Global Ionospheric Specification; ionospheric data assimilation; ionospheric response to magnetic storm; magnetosphere-ionosphere coupling; minor magnetic storm |
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The spatial distribution of aurora intensity is an important manifestation of solar wind-magnetosphere-ionosphere energy coupling process, and it oscillates with the change of space environment parameters and geomagnetic index. It is of great significance to establish an appropriate aurora intensity model for the prediction of space weather and the study of magnetosphere dynamics. Based on Ultraviolet Imager (UVI) data of Polar satellite, we constructed two auroral models by using two different neural networks, that is, the generalized regression neural network (GRNN), and the conditional generation adversarial network (CGAN). Input parameters of the models include interplanetary magnetic field, solar wind velocity and density, and the geomagnetic AE index. Output result is the spatial distribution of auroral intensity in altitude adjusted corrected geomagnetic (AACGM) coordinates. The structural similarity index (SSIM) of image quality is used as an evaluation standard of detail similarity between the prediction results of auroral intensity model and corresponding UVI images (complete similarity is 1, dissimilarity is 0, SSIM is generally considered to have good similarity if it is greater than 0.5). Based on the respective training datasets of GRNN and CGAN models, the evaluating results showed that the mean values (standard deviation) of SSIM were 0.5409 (0.0912) and 0.5876 (0.0712), respectively, so the prediction results from both models can restore the auroral intensity distribution of the original images of UVI. In addition, the value of SSIM can increase with the increase of the number of training data. Therefore, more training data will help improve the effectiveness of these models. Hu, Ze-Jun; Han, Bing; Zhang, Yisheng; Lian, Huifang; Wang, Ping; Li, Guojun; Li, Bin; Chen, Xiang-Cai; Liu, Jian-Jun; Published by: Space Weather Published on: YEAR: 2021 DOI: 10.1029/2021SW002751 conditional generation adversarial network; generalized regression neural network; interplanetary and geomagnetic parameters; neural networks; ultraviolet auroral intensity model |
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MLT science enabled by atmospheric lidars With the pioneering development and deployment of different types of narrowband sodium fluorescence lidars in Europe (1985) and North America (1990) along with subsequent potassium and iron lidars, temperature and wind profilers have been observed to investigate atmospheric dynamics in the mesosphere and lower thermosphere (MLT) in midlatitude, polar and equatorial regions. Their achieved resolution allows investigation ranging from small-scale gravity waves to long-term global change. This chapter highlights MLT science enabled by resonance fluorescence lidars in the past 30 years, divided into sections on climatology and long-term change of the atmospheric (background) state; MLT responses to external forcings that lead to atmospheric tides, the global-scale impacts of sudden stratospheric warming as well as geomagnetic storms; gravity wave dynamics and their fluxes; synergistic campaigns with lidars serving as a central instrument, and lidar observation of metal layers in the thermosphere at ever-higher altitudes. Recent advances in maintenance-free resonance lidars will increase the time and duration of lidar observation as well as their ease of operation. These should lead to more coherent multiple-day continuous observations of the MLT. Continued efforts to increase lidar signal/noise and to extend measurements from the main metal layers (80–110 km) into the lower thermosphere (up to 150 km) are ongoing. Further technology developments will also enable more lidar deployment on airplanes and in space to study the MLT over the oceans and other remote areas. She, Chiao-Yao; Liu, Alan; Yuan, Tao; Yue, Jia; Li, Tao; Ban, Chao; Friedman, Jonathan; Published by: Published on: YEAR: 2021 DOI: 10.1002/9781119815631.ch20 Geomagnetic storms; atmospheric stabilities; atmospheric state; climatology; clustered instrumentation; gravity wave dynamics; MLT science; resonance fluorescence lidars; sporadic metal layers; thermospheric metal layers |
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Ionospheric day-to-day variability is essential for understanding the space environment, while it is still challenging to properly quantify and forecast. In the present work, the day-to-day variability of F2 layer peak electron densities (NmF2) is examined from both observational and modeling perspectives. Ionosonde data over Wuhan station (30.5°N, 114.5°E; 19.3°N magnetic latitude) are compared with simulations from the specific dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (SD-WACCM-X) and the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) in 2009 and 2012. Both SD-WACCM-X and TIEGCM are driven by the realistic 3 h geomagnetic index and daily solar input, and the former includes self-consistently solved physics and chemistry in the lower atmosphere. The correlation coefficient between observations and SD-WACCM-X simulations is much larger than that of the TIEGCM simulations, especially during dusk in 2009 and nighttime in 2012. Both the observed and SD-WACCM-X simulated day-to-day variability of NmF2 reveal a similar day-night dependence in 2012 that increases large during the nighttime and decreases during the daytime, and shows favorable consistency of daytime variability in 2009. Both the observations and SD-WACCM-X simulations also display semiannual variations in nighttime NmF2 variability, although the month with maximum variability is slightly different. However, TIEGCM does not reproduce the day-night dependence or the semiannual variations well. The results emphasize the necessity for realistic lower atmospheric perturbations to characterize ionospheric day-to-day variability. This work also provides a validation of the SD-WACCM-X in terms of ionospheric day-to-day variability. Zhou, Xu; Yue, Xinan; Liu, Han-Li; Lu, Xian; Wu, Haonan; Zhao, Xiukuan; He, Jianhui; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028589 Ionosphere; day-to-day variability; ionosonde; NmF2; TIEGCM; WACCM-X |
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Implication of Tidal Forcing Effects on the Zonal Variation of Solstice Equatorial Plasma Bubbles Equatorial plasma bubbles (EPBs) are plasma depletions that can occur in the nighttime ionospheric F region, causing scintillation in satellite navigation and communications signals. Past research has shown that EPB occurrence rates are higher during the equinoxes in most longitude zones. An exception is over the central Pacific and African sectors, where EPB activity has been found to maximize during solstice. Tsunoda et al. (2015) hypothesized that the solstice maxima in these two sectors could be driven by a zonal wavenumber 2 atmospheric tide in the lower thermosphere. In this study, we utilize satellite observations to examine evidence of such a wave-2 feature preconditioning the nighttime ionosphere to favor higher EPB growth rates over these two regions. We find the postsunset total electron content (TEC) observed by FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) during boreal summer from 2007 to 2012 exhibits a wave-2 zonal distribution, consistent with elevated vertical plasma gradients favorable for EPB formation. Numerical experiments are also carried out to determine whether such an ionospheric wave-2 can be produced as a result of vertical coupling from atmospheric tides with zonal wavenumber 2 in the local time frame. We find that forcing from these tidal components produced increases in the Rayleigh-Taylor growth rate over both sectors during solar maximum and minimum, as well as wave-2 modulations on vertical ion drift, ion flux convergence, and nighttime TEC. Our results are consistent with the aforementioned hypothesis over both regions with vertical coupling effects from atmospheric tides preconditioning the nighttime ionosphere to favor higher EPB growth rates. Chang, Loren; Salinas, Cornelius; Chiu, Yi-Chung; , Jones; Rajesh, P.; Chao, Chi-Kuang; Liu, Jann-Yenq; Lin, Charles; Hsiao, Tung-Yuan; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028295 Ionosphere; Atmospheric tides; equatorial plasma bubble; scintillation; vertical coupling; wind dynamo |
| 2020 |
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Multi-scale ionosphere responses to the May 2017 magnetic storm over the Asian sector We investigate multi-scale ionospheric responses to the May 27, 2017, geomagnetic storm over the Asian sector by using multi-instrumental observations, including ground-based global navigation satellite systems (GNSS) network, constellation observing system for meteorology, ionosphere and climate radio occultation, the FengYun-3C (FY-3C) GNSS occultation sounder electron density profiles and in situ plasma density observations provided by both Swarm and defense meteorological satellite program missions. This geomagnetic storm was an intense storm with the minimum symmetric horizontal component reaching - 150\ nT and was caused by a coronal mass ejection released on May 23. The main observations are summarized below: (1) two ionospheric positive storm periods were observed. The first one was observed in the noon\textendashafternoon sector during the main phase of the storm on May 28, with nearly 120\% TEC enhancement. The second one was of a smaller scale and occurred on the nightside during the recovery phase of the storm on May 29. The first dayside positive storm was initiated by the interplanetary magnetic field (IMF) Bz southward turning and eastward penetration electric field, while the second nightside one was terminated by a later southward turning of the IMF Bz since the Asian sector was on the nightside and the penetration electric field changed westward. (2) A negative storm occurred from 00:00 to 12:00 UT on May 30 over the Asian sector, nearly 2\ days after the main phase, which was due to the thermospheric composition change, i.e., decrease in the O/N2 ratio, as shown in the TIMED/GUVI measurements. (3) A band-like TEC enhancement was observed aligning in the northwest\textendashsoutheast direction and propagated slowly southwestward from 15:00 to 20:00 UT (23:00\textendash04:00 LT, near midnight) on May 28 during the recovery phase of the storm. In situ density observations from the Swarm B and DMSP F15\&16 satellites confirmed the density enhancement at 510\ km and 850\ km, respectively, and revealed that this band-like TEC enhancement structure resembles the so-called plasma blob. The similarities of the observed plasma blob characteristics in terms of spatial structure, propagation trend and temporal evolution with the nighttime traveling ionospheric disturbance (TID) are consistent with the TID-blob theory. Liu, Lei; Zou, Shasha; Yao, Yibin; Aa, Ercha; Published by: GPS Solutions Published on: 12/2019 YEAR: 2020 DOI: 10.1007/s10291-019-0940-1 Blob structure; Positive and negative ionosphere responses; TID; Geomagnetic storms |
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Modeled IMF B y Effects on the Polar Ionosphere and Thermosphere Coupling There is still an inadequate understanding of how the interplanetary magnetic field (IMF) east-west component (By) affects thermospheric composition, and other ionospheric and thermospheric fields in a systematic way. Utilizing the state-of-art first-principles Coupled Magnetosphere Ionosphere Thermosphere (CMIT) modeling and TIMED/Global Ultraviolet Imager (GUVI)-observed ΣO/N2 covering an entire solar cycle (year 2002\textendash2016), as well as a neutral parcel trajectory tracing technique, we emphasize that not only the direction of By, but also its strength relative to the IMF north-south component (Bz) that has important effects on high latitude convection, Joule heating, electron density, neutral winds, and neutral composition patterns in the upper thermosphere. The Northern Hemisphere convection pattern becomes more twisted for positive By cases than negative cases: the dusk cell becomes more rounded compared with the dawn cell. Consequently, equatorward neutral winds are stronger during postmidnight hours in negative By cases than in positive By cases, creating a favorable condition for neutral composition disturbances (characterized by low ΣO/N2) to expand to lower latitudes. This may lead to a more elongated ΣO/N2 depletion area along the morning-premidnight direction for negative By conditions compared with the positive By conditions. Backward neutral parcel trajectories indicate that a lower ΣO/N2 parcel in negative By cases comes from lower altitudes, as compared with that for positive By cases, leading to larger enhancements of N2 in the former case. Liu, Jing; Burns, Alan; Wang, Wenbin; Zhang, Yongliang; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2020 YEAR: 2020 DOI: 10.1029/2019JA026949 |
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Understanding the Behavior of the Ionosphere—Thermosphere—Mesosphere at Solar Minimum I Paxton, Larry; Deng, Yue; Liu, Huixin; Fang, Tzu-Wei; Published by: Published on: |
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Plasma depletion bays in the equatorial ionosphere observed by FORMOSAT-3/COSMIC during 2007--2014 A new feature of plasma depletion bay (PDB) on the longitudinal structure over the equatorial and low latitudes is observed by the FORMOSAT-3/COSMIC (F3/C) electron density profiles. The existence of the PDB feature is confirmed by the OI 135.6 nm radiance from TIMED/GUVI, which together with F3/C electron density shows that one North PDB extending to the Southern Hemisphere prominently appears over Southwest America while three South PDBs extending to the Northern Hemisphere occur over North Atlantic, India Ocean, and Southeast Asia. Three-dimensional F3/C ionospheric electron densities are further used to examine PDB structures at various local times, seasons, solar activities, and altitudes during 2007−2014. Chang, FY; Liu, JY; Fang, TW; Rajesh, PK; Lin, CH; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2019JA027501 |
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Li, Qiaoling; Huang, Fuqing; Zhong, Jiahao; Zhang, Ruilong; Kuai, Jiawei; Lei, Jiuhou; Liu, Libo; Ren, Dexin; Ma, Han; Yoshikawa, Akimasa; , others; Published by: Journal of geophysical research: space physics Published on: |
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Wang, Zihan; Zou, Shasha; Ren, Jiaen; Aa, Ercha; Liu, Lei; Published by: Published on: |
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Paxton, Larry; Provornikova, Elena; Roelof, Edmond; emerais, Eric; Izmodenov, Vladislav; Katushkina, Olga; Mierkiewicz, Edwin; Baliukin, Igor; Gruntman, Mike; Taguchi, Makoto; , others; Published by: Published on: |
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Modeled IMF By effects on the polar ionosphere and thermosphere coupling Liu, Jing; Burns, Alan; Wang, Wenbin; Zhang, Yongliang; Published by: Journal of Geophysical Research: Space Physics Published on: |
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O 2 aurora is one kind of important molecular aurorae that is not fully understood yet. It is hard to be investigated due to the contamination by nightglow. In this work, we studied O 2 Gao, Hong; Xu, JiYao; Chen, Guang-Ming; Zhu, Yajun; Liu, Weijun; Wang, Chi; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2020JA028302 |
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In this paper we provide a comprehensive comparison of in situ electron density (Ne) and temperature (Te) measured by Langmuir probe (LAP) on board the China Seismo‐ Yan, Rui; Zhima, Zeren; Xiong, Chao; Shen, Xuhui; Huang, Jianping; Guan, Yibing; Zhu, Xinghong; Liu, Chao; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2019JA027747 |
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Prominent daytime TEC enhancements under the quiescent condition of January 2017 UltraViolet Imager (GUVI) for the longitude and latitude bins of 30 and 10, respectively. However, as shown in Figure 3c, the O/N 2 ratio from Global UltraViolet Imager (GUVI) had no Huang, Fuqing; Lei, Jiuhou; Zhang, Ruilong; Li, Na; Gu, Shengyang; Yu, You; Liu, Libo; Owolabi, Charles; Ning, Baiqi; Li, Guozhu; , others; Published by: Geophysical Research Letters Published on: YEAR: 2020 DOI: 10.1029/2020GL088398 |
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Comparison of GOLD nighttime measurements with total electron content: Preliminary results The National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb and Disk (GOLD) has been imaging the thermosphere and ionosphere since Cai, Xuguang; Burns, Alan; Wang, Wenbin; Coster, Anthea; Qian, Liying; Liu, Jing; Solomon, Stanley; Eastes, Richard; Daniell, Robert; McClintock, William; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2019JA027767 |
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Recent ionospheric investigations in China (2018—2019) (a) and (c) TIMED/GUVI data superimposed on the 557.7 nm ASI data at 19:55 UT and 21:33 UT, and the overpass of DMSP F13 crossing the PCA superimposed on the image, shown Published by: Earth and Planetary Physics Published on: YEAR: 2020 DOI: 10.26464/epp2020028 |
| 2019 |
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The geomagnetic storm-driven ionospheric changes and the involved processes are interesting and challenging topics in understanding and predicting the ionosphere. In this study we investigate the response of the ionosphere to geomagnetic disturbances during the 30-day incoherent scatter radar measurements conducted at Millstone Hill (42.6\textdegreeN, 71.5\textdegreeW) from 4 October to 4 November 2002. During geomagnetically disturbed periods, while the peak electron density of the F2 layer (NmF2) and total electron content deviate remarkably from the quiet time ones in a similar way, the incoherent scatter radar measurements reveal that the changes in electron density are frequently different between low and high altitudes. The electron density is significantly depleted at low altitudes; however, at topside it either changes slightly or sometime is enhanced. The enhanced vertical scale height around 600 km under geomagnetically active conditions implies that the topside electron density profiles become much steeper. The increase in the peak height of F2 layer (hmF2) indicates the upward motions under the action of the storm-driven dynamic processes. Further, sometimes strong differences are shown in total electron content between Millstone Hill and longitude 100\textdegreeW. The competing contributions from dynamic processes and disturbance composition to the storm-time ionospheric changes over Millstone Hill are indicated in the different responses in electron density at the bottomside and topside of the ionosphere. Liu, Libo; Le, Huijun; Chen, Yiding; Zhang, Ruilong; Wan, Weixing; Zhang, Shun-Rong; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2019 YEAR: 2019 DOI: 10.1029/2019JA026806 |
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Wide-field auroral imager onboard the Fengyun satellite The newly launched Fengyun-3D (FY-3D) satellite carried a wide-field auroral imager (WAI) that was developed by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), which will provide a large field of view (FOV), high spatial resolution, and broadband ultraviolet images of the aurora and the ionosphere by imaging the N2 LBH bands of emissions. The WAI consists of two identical cameras, each with an FOV of 68\textdegree in the along-track direction and 10\textdegree in the cross-track direction. The two cameras are tilted relative to each other to cover a fan-shaped field of size 130\textdegree \texttimes 10\textdegree. Each camera consists of an unobstructed four-mirror anastigmatic optical system, a BaF2 filter, and a photon-counting imaging detector. The spatial resolution of WAI is ~10 km at the nadir point at a reference height of 110 km above the Earth\textquoterights surface. The sensitivity is \>0.01 counts s-1 Rayleigh-1 pixel-1 (140\textendash180 nm) for both cameras, which is sufficient for mapping the boundaries and the fine structures of the auroral oval during storms/substorms. Based on the tests and calibrations that were conducted prior to launch, the data processing algorithm includes photon signal decoding, geometric distortion correction, photometric correction, flat-field correction, line-of-sight projection and correction, and normalization between the two cameras. Preliminarily processed images are compared with DMSP SSUSI images. The agreement between the images that were captured by two instruments demonstrates that the WAI and the data processing algorithm operate normally and can provide high-quality scientific data for future studies on auroral dynamics. Zhang, Xiao-Xin; Chen, Bo; He, Fei; Song, Ke-Fei; He, Ling-Ping; Liu, Shi-Jie; Guo, Quan-Feng; Li, Jia-Wei; Wang, Xiao-Dong; Zhang, Hong-Ji; Wang, Hai-Feng; Han, Zhen-Wei; Sun, Liang; Zhang, Pei-Jie; Dai, Shuang; Ding, Guang-Xing; Chen, Li-Heng; Wang, Zhong-Su; Shi, Guang-Wei; Zhang, Xin; Yu, Chao; Yang, Zhong-Dong; Zhang, Peng; Wang, Jin-Song; Published by: Light: Science \& Applications Published on: 05/2019 YEAR: 2019 DOI: 10.1038/s41377-019-0157-7 |
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Anomaly distribution of ionospheric total electron content responses to some solar flares Le, Huijun; Liu, Libo; Chen, Yiding; Zhang, Hui; Published by: Earth and Planetary Physics Published on: |
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We use the observations from the incoherent scatter radar and the magnetometers over Jicamarca (11.95 S, 76.87 W) sector to investigate the equatorial ionospheric electrodynamics Zhang, Ruilong; Liu, Libo; Le, Huijun; Chen, Yiding; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2019 DOI: 10.1029/2018JA026295 |
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IMF B y Effects on the high-latitude Ionosphere and Thermosphere Liu, Jing; Wang, Wenbin; Burns, Alan; Zhang, Yongliang; Published by: Published on: |
| 2018 |
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Transition of Interhemispheric Asymmetry of Equatorial Ionization Anomaly During Solstices The magnitudes of the two crests of equatorial ionization anomaly (EIA) vary with local time. During the solstices, EIA crest in the winter hemisphere is larger than that in the summer hemisphere before noon/early afternoon. Whereafter, the crest in the summer hemisphere becomes intensified, and the stronger EIA crest transits to the summer hemisphere. Using Constellation Observing System for Meteorology, Ionosphere, and Climate ionospheric radio occultation data, we examine the longitudinal and altitudinal variations of this interhemispheric transition in four longitudinal sectors and at seven heights under low/high solar activity conditions. The results show that during the June solstice the transition of the stronger EIA peak from the winter to the summer hemisphere is earlier in the sectors where the geomagnetic equator is further away from the subsolar point and the geomagnetic field declination is larger, while during the December solstice the longitudinal variations generally show the opposite compared with that in the June solstice. The distance between the geomagnetic equator and subsolar point and the geomagnetic field configuration control the upward/downward plasma movements in the summer/winter hemisphere, leading to the different transition times in different longitudinal sectors. For both solstices, transition times emerge earlier as height increases, which is mainly caused by the larger effective scale height in the summer hemisphere than in the winter hemisphere, resulting in a smaller electron density difference at higher altitudes with a fast transition. Solar activity alters the transition time below 320\ km, whereas it has no evident effect at higher altitudes. Huang, He; Lu, Xian; Liu, Libo; Wang, Wenbin; Li, Qiaoling; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2018 YEAR: 2018 DOI: 10.1029/2018JA026055 |
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Observations from lidars and satellites have shown that large neutral temperature increases and decreases occur in the middle and low latitudes of the mesosphere and lower thermosphere region during geomagnetic storms. Here we undertake first-principles simulations of mesosphere and lower thermosphere temperature responses to storms using the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model to elucidate the nature and causes of these changes. Temperature variations were not uniform; instead, nighttime temperatures changed earlier than daytime temperatures, and temperatures changed earlier at high latitudes than at low ones. Furthermore, temperatures increased in some places/times and decreased in others. As the simulation behaves similar to observations, it provides an opportunity to understand physical processes that drive the observed changes. Our analysis has shown that they were produced mainly by adiabatic heating/cooling that was associated with vertical winds resulting from general circulation changes, with additional contributions from vertical heat advection. Li, Jingyuan; Wang, Wenbin; Lu, Jianyong; Yuan, Tao; Yue, Jia; Liu, Xiao; Zhang, Kedeng; Burns, Alan; Zhang, Yongliang; Li, Zheng; Published by: Geophysical Research Letters Published on: 08/2019 YEAR: 2018 DOI: 10.1029/2018GL078968 |
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Key developments have been made to the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Among them, the most important are the self-consistent solution of global electrodynamics, and transport of O+ in the F-region. Other ionosphere developments include time-dependent solution of electron/ion temperatures, metastable O+ chemistry, and high-cadence solar EUV capability. Additional developments of the thermospheric components are improvements to the momentum and energy equation solvers to account for variable mean molecular mass and specific heat, a new divergence damping scheme, and cooling by O(3P) fine structure. Simulations using this new version of WACCM-X (2.0) have been carried out for solar maximum and minimum conditions. Thermospheric composition, density, and temperatures are in general agreement with measurements and empirical models, including the equatorial mass density anomaly and the midnight density maximum. The amplitudes and seasonal variations of atmospheric tides in the mesosphere and lower thermosphere are in good agreement with observations. Although global mean thermospheric densities are comparable with observations of the annual variation, they lack a clear semiannual variation. In the ionosphere, the low-latitude E \texttimes B drifts agree well with observations in their magnitudes, local time dependence, seasonal, and solar activity variations. The prereversal enhancement in the equatorial region, which is associated with ionospheric irregularities, displays patterns of longitudinal and seasonal variation that are similar to observations. Ionospheric density from the model simulations reproduces the equatorial ionosphere anomaly structures and is in general agreement with observations. The model simulations also capture important ionospheric features during storms. Liu, Han-Li; Bardeen, Charles; Foster, Benjamin; Lauritzen, Peter; Liu, Jing; Lu, Gang; Marsh, Daniel; Maute, Astrid; McInerney, Joseph; Pedatella, Nicholas; Qian, Liying; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Vitt, Francis; Wang, Wenbin; Published by: Journal of Advances in Modeling Earth Systems Published on: 01/2018 YEAR: 2018 DOI: 10.1002/jame.v10.210.1002/2017MS001232 |
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Key developments have been made to the NCAR Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Among them, the most important are the self-consistent solution of global electrodynamics, and transport of O+ in the F-region. Other ionosphere developments include time-dependent solution of electron/ion temperatures, metastable O+ chemistry, and high-cadence solar EUV capability. Additional developments of the thermospheric components are improvements to the momentum and energy equation solvers to account for variable mean molecular mass and specific heat, a new divergence damping scheme, and cooling by O(3P) fine structure. Simulations using this new version of WACCM-X (2.0) have been carried out for solar maximum and minimum conditions. Thermospheric composition, density, and temperatures are in general agreement with measurements and empirical models, including the equatorial mass density anomaly and the midnight density maximum. The amplitudes and seasonal variations of atmospheric tides in the mesosphere and lower thermosphere are in good agreement with observations. Although global mean thermospheric densities are comparable with observations of the annual variation, they lack a clear semiannual variation. In the ionosphere, the low-latitude E \texttimes B drifts agree well with observations in their magnitudes, local time dependence, seasonal, and solar activity variations. The prereversal enhancement in the equatorial region, which is associated with ionospheric irregularities, displays patterns of longitudinal and seasonal variation that are similar to observations. Ionospheric density from the model simulations reproduces the equatorial ionosphere anomaly structures and is in general agreement with observations. The model simulations also capture important ionospheric features during storms. Liu, Han-Li; Bardeen, Charles; Foster, Benjamin; Lauritzen, Peter; Liu, Jing; Lu, Gang; Marsh, Daniel; Maute, Astrid; McInerney, Joseph; Pedatella, Nicholas; Qian, Liying; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Vitt, Francis; Wang, Wenbin; Published by: Journal of Advances in Modeling Earth Systems Published on: 01/2018 YEAR: 2018 DOI: 10.1002/jame.v10.210.1002/2017MS001232 |
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Temporal Variability of Atomic Hydrogen From the Mesopause to the Upper Thermosphere We investigate atomic hydrogen (H) variability from the mesopause to the upper thermosphere, on time scales of solar cycle, seasonal, and diurnal, using measurements made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics Dynamics satellite, and simulations by the National Center for Atmospheric Research Whole Atmosphere Community Climate Model-eXtended (WACCM-X). In the mesopause region (85 to 95\ km), the seasonal and solar cycle variations of H simulated by WACCM-X are consistent with those from SABER observations: H density is higher in summer than in winter, and slightly higher at solar minimum than at solar maximum. However, mesopause region H density from the Mass-Spectrometer-Incoherent-Scatter (National Research Laboratory Mass-Spectrometer-Incoherent-Scatter 00 (NRLMSISE-00)) empirical model has reversed seasonal variation compared to WACCM-X and SABER. From the mesopause to the upper thermosphere, H density simulated by WACCM-X switches its solar cycle variation twice, and seasonal dependence once, and these changes of solar cycle and seasonal variability occur in the lower thermosphere (~95 to 130\ km), whereas H from NRLMSISE-00 does not change solar cycle and seasonal dependence from the mesopause through the thermosphere. In the upper thermosphere (above 150\ km), H density simulated by WACCM-X is higher at solar minimum than at solar maximum, higher in winter than in summer, and also higher during nighttime than daytime. The amplitudes of these variations are on the order of factors of ~10, ~2, and ~2, respectively. This is consistent with NRLMSISE-00. Qian, Liying; Burns, Alan; Solomon, Stan; Smith, Anne; McInerney, Joseph; Hunt, Linda; Marsh, Daniel; Liu, Hanli; Mlynczak, Martin; Vitt, Francis; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2018 YEAR: 2018 DOI: 10.1002/2017JA024998 |