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Found 18 entries in the Bibliography.
Showing entries from 1 through 18
| 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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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 |
| 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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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 |
| 2014 |
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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 |
| 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 |
| 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: |
| 2011 |
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GPS Ionospheric Mapping and Tomography: A case of study in a geomagnetic storm Published by: Published on: |
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GPS Ionospheric Mapping and Tomography: A case of study in a geomagnetic storm Published by: Published on: |
| 2010 |
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Program of transient UV event research at Tatiana-2 satellite Garipov, G.; Khrenov, B.; Klimov, P.; Morozenko, V.; Panasyuk, M.; Petrova, S.; Tulupov, V.; Shahparonov, V.; Svertilov, S.; Vedenkin, N.; Yashin, I.; Jeon, J.; Jeong, S.; Jung, A.; Kim, J.; Lee, J.; Lee, H; Na, G.; Nam, J.; Nam, S.; Park, I.; Suh, J.; Jin, J; Kim, M.; Kim, Y.; Yoo, B.; Park, Y.-S.; Yu, H.; Lee, C.-H.; Park, J.; Salazar, H.; Martinez, O.; Ponce, E.; Cotsomi, J.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JA014765 |
| 2009 |
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Retrieval of ionospheric O/N Solar storms in the ionosphere have a great impact on human\textquoterights life. It\textquoterights of great significance to find an effective way for an accurate prediction of solar storms. In this paper, we present a method based on GUVI FUV day-glow imaging data to derive O/N2, an environmental parameter used to forecast Space Weather. In the retrieval, we selected two channels of the FUV wavelengths, OI135.6nm and LBH2. In accordance with the linear relationship between O/N2 and 135.6/LBH, we proposed 135.6/LBH to describe O/N2. With the method described in this paper, the data of a 4-day solar storm, October 1 to 4, 2002, have been processed. Subsequently, the obtained O/N2 maps were in good agreement with previous results. It demonstrated the retrieval process we put up is efficient. Jing, Wang; Tang, Yi; Tang, Li-jun; Ni, Guo-qiang; Published by: Published on: YEAR: 2009 DOI: 10.1117/12.833985 |
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Retrieval of ionospheric O/N2 based on FUV imaging data Jing, Wang; Tang, Yi; Tang, Li-jun; Ni, Guo-qiang; Published by: Published on: |
| 2008 |
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The ionospheric F2-layer peak density (NmF2) and its height (hmF2) are of great influence on the shape of the ionospheric electron density profile Ne (h) and may be indicative of other physical processes within the ionosphere, especially those due to geomagnetic storms. Such parameters are often estimated using models such as the semiempirical international reference ionosphere (IRI) models or are measured using moderately priced to expensive instrumentation, such as ionosondes or incoherent scatter radars. Global positioning system (GPS) observations have become a powerful tool for mapping high-resolution ionospheric structures, which can be used to study the ionospheric response to geomagnetic storms. In this paper, we describe how 3-D ionospheric electron density profiles were produced from data of the dense permanent Korean GPS network using the tomography reconstruction technique. These profiles are verified by independent ionosonde data. The responses of GPS-derived parameters at the ionospheric F2-layer to the 20th November 2003 geomagnetic storm over South Korea are investigated. A fairly large increase in the electron density at the F2-layer peak (the NmF2) (positive storm) has been observed during this storm, which is accompanied by a significant uplift in the height of the F2 layer peak (the hmF2). This is confirmed by independent ionosonde observations. We suggest that the F2-layer peak height uplift and NmF2 increase are mainly associated with a strong eastward electric field, and are not associated with the increase of the O/N2 ratio obtained from the GUVI instruments aboard the TIMED satellite. It is also inferred that the increase in NmF2 is not caused by the changes in neutral composition, but is related to other nonchemical effects, such as dynamical changes of vertical ion motions induced by winds and E\ \texttimes\ B drifts, tides and waves in the mesosphere/lower thermosphere region, which can be dynamically coupled upward to generate ionospheric perturbations and oscillations. Jin, Shuanggen; Luo, O.; Park, P.; Published by: Journal of Geodesy Published on: 03/2008 YEAR: 2008 DOI: 10.1007/s00190-008-0217-x |
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