Bibliography
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Found 51 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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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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Seasonal Variation of Thermospheric Composition Observed by NASA GOLD We examine characteristics of the seasonal variation of thermospheric composition using column number density ratio ∑O/N2 observed by the NASA Global Observations of Limb and Disk (GOLD) mission from low-mid to mid-high latitudes. We also use ∑O/N2 derived from the Global Ultraviolet Imager (GUVI) limb measurements onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and estimated by the NRLMSISE-00 empirical model to aid our investigation. We found that the ∑O/N2 seasonal variation is hemispherically asymmetric: in the southern hemisphere, it exhibits the well-known annual and semiannual pattern, with highs near the equinoxes, and primary and secondary lows near the solstices. In the northern hemisphere, it is dominated by an annual variation, with a minor semiannual component with the highs shifting toward the wintertime. We also found that the durations of the December and June solstice seasons in terms of ∑O/N2 are highly variable with longitude. Our hypothesis is that ion-neutral collisional heating in the equatorial ionization anomaly region, ion drag, and auroral Joule heating play substantial roles in this longitudinal dependency. Finally, the rate of change in ∑O/N2 from one solstice season to the other is dependent on latitude, with more dramatic changes at higher latitudes. Qian, Liying; Gan, Quan; Wang, Wenbin; Cai, Xuguang; Eastes, Richard; Yue, Jia; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2022JA030496 annual variation; GOLD observation; MSIS; seasonal variation; semiannual variation; thermosphere composition |
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In the mesosphere and lower thermosphere (MLT) region, residual circulations driven by gravity wave breaking and dissipation significantly impact constituent distribution and the height and temperature of the mesopause. The distribution of CO2 can be used as a proxy for the residual circulations. Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) CO2 volume mixing ratio (VMR) and temperature measurements from 2003 to 2020 are used to study the monthly climatology of MLT residual circulations and the mesopause height. Our analyses show that (a) mesopause height strongly correlates with the CO2 VMR vertical gradient during solstices; (b) mesopause height has a discontinuity at midlatitude in the summer hemisphere, with a lower mesopause height at mid-to-high latitudes as a result of adiabatic cooling driven by strong adiabatic upwelling; (c) the residual circulations have strong seasonal variations at mid-to-high latitudes, but they are more uniform at low latitudes; and (d) the interannual variability of the residual circulations and mesopause height is larger in the Southern Hemisphere (SH; 4–5 km) than in the Northern Hemisphere (NH; 0.5–1 km). Wang, Ningchao; Qian, Liying; Yue, Jia; Wang, Wenbin; Mlynczak, Martin; Russell, James; Published by: Journal of Geophysical Research: Atmospheres Published on: YEAR: 2022 DOI: 10.1029/2021JD035666 climatology; interannual variation; MLT region; residual circulation; seasonal variation |
| 2021 |
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Accurate specification of the thermosphere states is crucial to the low Earth orbit satellite operation. In this work, the impact of different ionosphere and thermosphere observing systems on the improvement of neutral temperature of the data assimilation model has been investigated by a series of observing system simulation experiments. The selected observations include the Global Navigation Satellite System total electron content (e.g., MIT vertical total electron content [VTEC]) and the daytime Global-scale Observations of the Limb and Disk (GOLD) level-2 disk temperature (Tdisk). Such observations are ingested into the coupled ionosphere and thermosphere model based on our developed ensemble Kalman Filter data assimilation systems on the basis of the ensemble Kalman filter algorithm and the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model. The main findings are as follows: (a) A considerable improvement of the neutral temperature estimation of the physical-based model can be obtained in the global region by assimilating either the MIT VTEC or the GOLD Tdisk observations; (b) the assimilation of the GOLD can further contribute to temperature improvement in the lower thermosphere (\textless200 km), relative to the MIT VTEC assimilation; and (c) simultaneously assimilating both observation types can better improve the quality of neutral temperature estimation over the global area during the whole data assimilation process. The current results demonstrate that assimilating GOLD observations is important to improve the forecast capability of the physical-based model for the lower thermosphere states and can provide a possible reference for the joint assimilation of the ionosphere and thermosphere observations to better thermosphere specification. He, Jianhui; Yue, Xinan; Ren, Zhipeng; Published by: Space Weather Published on: YEAR: 2021 DOI: 10.1029/2021SW002844 |
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Yu, Tingting; Wang, Wenbin; Ren, Zhipeng; Cai, Xuguang; Yue, Xinan; He, Maosheng; Published by: Journal of Geophysical Research: Space Physics Published on: |
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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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Planetary Waves and Their Impact on the Mesosphere, Thermosphere, and Ionosphere Large-scale planetary waves (also known as Rossby waves), such as the Quasi-two day wave, 5 day wave and Kelvin wave, play crucial roles in coupling the lower and middle atmosphere to the mesosphere, thermosphere and ionosphere. Upward propagation and global structure of planetary waves in the stratosphere and mesosphere are affected by the zonal mean winds. Baroclinic or barotropic instability of the background mesospheric winds can amplify the waves en route to the upper atmosphere. Fast traveling planetary waves with deep vertical wavelengths, such as Kelvin waves, are able to reach the upper thermosphere and modulate air density and winds. More commonly, planetary waves influence the thermosphere-ionosphere system by modulating the E-region and F-region dynamo electric fields. Dissipation of planetary waves in the lower thermosphere modifies the background winds, and induces extra meridional circulation, consequently altering thermospheric constituents, such as O/N2, and ionospheric electron densities. Interactions between planetary waves and tides not only provide an additional source of traveling planetary waves in the mesosphere, but are key sources of variability in E-region dynamo electric fields and plasma drift. Yue, Jia; Lieberman, Ruth; Chang, Loren; Published by: Published on: YEAR: 2021 DOI: 10.1002/9781119815631.ch10 barotropic instability; E-region dynamo electric fields; F-region dynamo electric fields; Kelvin waves; mesosphere; planetary waves; plasma drift; thermosphere-ionosphere system |
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TIMED/Global Ultraviolet Imager (GUVI) limb measurements of far-ultraviolet airglow emission have been used to investigate middle-low latitude thermospheric composition and neutral temperature responses to the 20 and 21 November 2003 (day of year [DOY] 324 and 325) superstorm. Altitude profiles of O, N2 number densities and temperature, as well as O/N2 column density ratio (∑O/N2), on the storm days along the GUVI limb tracks are compared with those on DOY 323 (quiet time). The storm-time composition and temperature responses were global and evolved continuously as the storm progressed. Specially, N2 and temperature increased almost globally at all altitudes during the storm and their perturbation structures were similar. The magnitudes of their enhancements both increased with altitude and latitude. The storm-induced O perturbations decreased in the lower thermosphere but increased in the upper thermosphere. Transition heights of O perturbations from decrease to increase changed with latitude and time. During the storm main and recovery phases, the storm-induced ∑O/N2 decreases were mostly related to the O depletion in the low-middle thermosphere, whereas ∑O/N2 increases during the storm were primarily caused by N2 depletion. There was a remarkable hemispheric asymmetry in composition responses as they have different morphologies and lifetime, especially during the storm recovery phase. Yu, Tingting; Wang, Wenbin; Ren, Zhipeng; Yue, Jia; Yue, Xinan; He, Maosheng; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028427 neutral composition; altitude profile; hemispheric asymmetry in composition responses; neutral temperature; superstorm; transition heights of O responses |
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TIMED/Global Ultraviolet Imager (GUVI) limb measurements of far-ultraviolet airglow emission have been used to investigate middle-low latitude thermospheric composition and neutral temperature responses to the 20 and 21 November 2003 (day of year [DOY] 324 and 325) superstorm. Altitude profiles of O, N2 number densities and temperature, as well as O/N2 column density ratio (∑O/N2), on the storm days along the GUVI limb tracks are compared with those on DOY 323 (quiet time). The storm-time composition and temperature responses were global and evolved continuously as the storm progressed. Specially, N2 and temperature increased almost globally at all altitudes during the storm and their perturbation structures were similar. The magnitudes of their enhancements both increased with altitude and latitude. The storm-induced O perturbations decreased in the lower thermosphere but increased in the upper thermosphere. Transition heights of O perturbations from decrease to increase changed with latitude and time. During the storm main and recovery phases, the storm-induced ∑O/N2 decreases were mostly related to the O depletion in the low-middle thermosphere, whereas ∑O/N2 increases during the storm were primarily caused by N2 depletion. There was a remarkable hemispheric asymmetry in composition responses as they have different morphologies and lifetime, especially during the storm recovery phase. Yu, Tingting; Wang, Wenbin; Ren, Zhipeng; Yue, Jia; Yue, Xinan; He, Maosheng; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2020JA028427 neutral composition; altitude profile; hemispheric asymmetry in composition responses; neutral temperature; superstorm; transition heights of O responses |
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The Response of Middle Thermosphere (∼160 km) Composition to the November 20 and 21, 2003 Superstorm TIMED/GUVI limb measurements and first-principles simulations from the Thermosphere Ionosphere Electrodynamics Global Circulation Model (TIEGCM) are used to investigate thermospheric atomic oxygen (O) and molecular nitrogen (N2) responses in the middle thermosphere on a constant pressure surface (∼160 km) to the November 20 and 21, 2003 superstorm. The consistency between GUVI observations and TIEGCM simulated composition changes allows us to utilize TIEGCM outputs to investigate the storm-time behaviors of O and N2 systematically. Diagnostic analysis shows that horizontal and vertical advection are the two main processes that determine the storm-induced perturbations in the middle thermosphere. Molecular diffusion has a relatively smaller magnitude than the two advection processes, acting to compensate for the changes caused by the transport partly. Contributions from chemistry and eddy diffusion are negligible. During the storm initial and main phases, composition variations at high latitudes are determined by both horizontal and vertical advection. At middle-low latitudes, horizontal advection is the main driver for the composition changes where O mass mixing ratio decreases (N2 mass mixing ratio increases); whereas horizontal and vertical advection combined to dominate the changes in the regions where increases ( decreases). Over the entire storm period, horizontal advection plays a significant role in transporting high-latitude composition perturbations globally. Our results also demonstrate that storm-time temperature changes are not the direct cause of the composition perturbations on constant pressure surfaces. Yu, Tingting; Wang, Wenbin; Ren, Zhipeng; Cai, Xuguang; Yue, Xinan; He, Maosheng; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029449 atomic oxygen; GUVI limb observations; middle thermosphere; molecular nitrogen; storm-time perturbations; TIEGCM |
| 2020 |
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In this work, we evaluated the quasi-realistic ionosphere forecasting capability by an ensemble Kalman filter (EnKF) ionosphere and thermosphere data assimilation algorithm. The National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model is used as the background model in the system. The slant total electron contents (TECs) from global International Global Navigation Satellite Systems Service ground-based receivers and from the Constellation Observing System for Meteorology, Ionosphere and Climate are assimilated into the system, and the ionosphere is then predicted in advance during the quiet interval of 23 to 27 March 2010. The predicted ionosphere vertical TEC (VTEC) and the critical frequency foF2 are validated by the Massachusetts Institute of Technology VTEC and global ionosondes network, respectively. We found that the ionosphere forecast quality could be enhanced by optimizing the thermospheric neutral components via the EnKF method. The ionosphere electron density forecast accuracy can be improved by at least 10\% for 24 hr. Furthermore, the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI) [O/N2] observations are used to validate the predicted thermosphere [O/N2]. The validation shows that the [O/N2] optimized by EnKF has better agreement with the TIMED/GUVI observation. This study further demonstrates the validity of EnKF in enhancing the ionospheric forecast capability in addition to our previous observing system simulation experiments by He et al. (2019, https://doi.org/10.1029/2019JA026554). He, Jianhui; Yue, Xinan; Le, Huijun; Ren, Zhipeng; Wan, Weixing; Published by: Space Weather Published on: 02/2020 YEAR: 2020 DOI: 10.1029/2019SW002410 |
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Comparison of Reference Heights of O/N 2 and ∑O/N 2 Based on GUVI Dayside Limb Measurement We define a new thermospheric concept, the reference heights of O/N2, referring to a series of thermospheric heights corresponding to the fixed ratios of O to N2 number density. Here, based on Global Ultraviolet Imager (GUVI) limb measurement, we compare O/N2 column density ratio (∑O/N2) and the reference heights of O/N2. We choose the transition height of O and N2 (transition height hereafter), a special reference height at which O number density is equal to N2 number density, to verify the connection with ∑O/N2 during geomagnetically quiet periods. It is found that transition height and ∑O/N2 have noticeable negative correlation with correlation coefficient of -0.887. An empirical model of transition height (O/N2 model hereafter) is established based on nonlinear least-squares-fitting method. The considerable correlation (greater than 0.96), insignificant errors (less than 4\%) and the great influencing weight of ∑O/N2 to reference heights indicate the validity of O/N2 model and the existence of quantitative relation between ∑O/N2 and transition height. Besides, it is verified that the similar quantitative relation also exists between ∑O/N2 and reference heights of other O/N2 values. Namely, using the O/N2 model coefficients, we can roughly get the whole altitude profiles of O/N2 within 6\% precision for any given ∑O/N2. Yu, Tingting; Ren, Zhipeng; Yu, You; Yue, Xinan; Zhou, Xu; Wan, Weixing; Published by: Space Weather Published on: 01/2020 YEAR: 2020 DOI: 10.1029/2019SW002391 |
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Comparison of reference heights of O/N2 and∑ O/N2 based on GUVI dayside limb measurement Yu, Tingting; Ren, Zhipeng; Yu, You; Yue, Xinan; Zhou, Xu; Wan, Weixing; Published by: Space weather Published on: |
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Published by: Chinese Journal of Geophysics Published on: |
| 2019 |
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Annual and Semiannual Oscillations of Thermospheric Composition in TIMED/GUVI Limb Measurements The Global UltraViolet Imager (GUVI) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite provides a data set of vertical thermospheric composition (O, N2, and O2 densities) and temperature profiles from 2002\textendash2007. Even though GUVI sampling is limited by orbital constraint, we demonstrated that the GUVI data set can be used to derive the altitude profiles of the amplitudes and phases of annual oscillation (AO) and semiannual oscillation (SAO), thereby providing important constraints on models seeking to explain these features. We performed a seasonal and interannual analysis of GUVI limb O, O2, and N2 densities and volume number density ratio O/N2 at constant pressure levels. These daytime observations of O and O/N2 in the lower thermosphere show a strong AO at midlatitudes and a clear SAO at lower latitudes. The global mean GUVI O/N2 number density ratio shows the AO, with slightly larger values in January than in July and a SAO with O/N2 greater during equinoxes than at the solstices. O and N2 densities on fixed pressure levels in the upper thermosphere are anticorrelated with solar extreme ultraviolet flux. On the other hand, O/N2 is smaller during solar minimum and larger during solar maximum. The thermospheric AO and SAO in composition have a constant phase with altitude throughout the thermosphere. Yue, Jia; Jian, Yongxiao; Wang, Wenbin; Meier, R.R.; Burns, Alan; Qian, Liying; Jones, M.; Wu, Dong; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2019 YEAR: 2019 DOI: 10.1029/2019JA026544 |
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The Global Ultraviolet Imager (GUVI) aboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite senses far ultraviolet airglow emissions in the thermosphere. The retrieved altitude profiles of thermospheric neutral density from GUVI daytime limb scans are significant for ionosphere-thermosphere study. Here, we use the profiles of the main neutral density to derive the total mass density during the period 2002\textendash2007 under geomagnetic quiet conditions (ap\ \<\ =12). We attempt to compare the obtained total mass density with the Challenging Minisatellite Payload (CHAMP) observations, making use of an empirical model (GUVI model hereafter). This GUVI model is aimed to solve the difficulty of the direct comparison of GUVI and CHAMP observations due to their different local times at a given location in a given day. The GUVI model is in good agreement with CHAMP observations with the small standard deviations of their ratios (less than 10\%) except at low solar flux levels. The correlation coefficients are greater than 0.9, and the relative standard errors are less than 20\%. Comparison between the GUVI model and CHAMP observations during solar minimum shows a large bias (~30\%). The large bias at low solar flux levels might be due to the limitation of F10.7 as an extreme ultraviolet radiation flux proxy and the fitting method. Our results demonstrate the validity and accuracy of our model based on GUVI data against the density data from the CHAMP satellite. Yu, Tingting; Ren, Zhipeng; Yue, Xinan; Yu, You; Wan, Weixing; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2019 YEAR: 2019 DOI: 10.1029/2018JA026229 |
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Planetary wave-like oscillations in thermospheric composition Yue, Jia; Lieberman, Ruth; Wang, Wenbin; Jian, Yongxiao; Published by: Published on: |
| 2018 |
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Ionospheric and Thermospheric Responses to the Recent Strong Solar Flares on 6 September 2017 Two solar flares X2.2 and X9.3 erupted over the active region 2673 on 6 September 2017, and the second flare is the strongest since 2005. In order to investigate the ionospheric and thermospheric responses to the two solar flares, the global total electron content and the critical frequency of F2 layer obtained from GPS stations and ionosondes are used. The results indicate that the ionosphere in the sunlit hemisphere increased significantly with magnitudes of 0.1 and 0.5 total electron content units for the X2.2 and X9.3 solar flares, respectively. The electron density, thermospheric neutral density, and neutral temperature simulated by the Thermosphere-Ionosphere Electrodynamics Global Circulation Model show that the behavior of ionospheric and thermospheric responses is different. The ionospheric disturbances occurred at the altitude ranges of 150-300\ km, and the thermospheric responses occurred at the altitudes of 250-400\ km are caused by solar extreme ultraviolet and ultraviolet photons, respectively. Both ionospheric and thermospheric responses are proportional to the height within their corresponding altitude ranges. Observations and simulations reveal that the ionospheric and thermospheric responses are nonlinearly dependent on the solar zenith angle. The disturbances caused by the X2.2 solar flare are symmetric, but the X9.3 solar flare are not. The O/N2 density ratio simulated by Thermosphere-Ionosphere Electrodynamics Global Circulation Model increases from lev0 to lev5.0 pressure surface with a magnitude of 0.1\textendash1.8, while the ratio decreases in the American sector with a magnitude of -0.6 to -0.3. The longitudinal asymmetry of O/N2 density ratio is a major contributor to the longitudinal asymmetry of ionospheric and thermospheric responses. Li, Wang; Yue, Jianping; Yang, Yang; He, Changyong; Hu, Andong; Zhang, Kefei; Published by: Journal of Geophysical Research: Space Physics Published on: 10/2018 YEAR: 2018 DOI: 10.1029/2018JA025700 |
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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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Wang, Jack; Tsai-Lin, Rong; Chang, Loren; Wu, Qian; Lin, Charles; Yue, Jia; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 06/2018 YEAR: 2018 DOI: 10.1016/j.jastp.2017.07.024 |
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In this study, multiple data sets from Beidou geostationary orbit satellites total electron contents (TECs), ionosonde, meteor radar, magnetometer, and model simulations have been used to investigate the ionospheric responses in the Asian-Australian sector during the September 2017 geomagnetic storm. It was found that long-duration daytime TEC enhancements that lasted from 7 to 12 September 2017 were observed by the Beidou geostationary orbit satellite constellation. This is a unique event as the prominent TEC enhancements persisted during the storm recovery phase when geomagnetic activity became quiet. The Thermosphere-Ionosphere Electrodynamics Global Circulation Model predicted that the TEC enhancements on 7\textendash9 September were associated with the geomagnetic activity, but it showed significant electron density depletions on 10 and 11 September in contrast to the observed TEC enhancements. Our results suggested that the observed long-duration TEC enhancements from 7 to 12 September are mainly associated with the interplay of ionospheric dynamics and electrodynamics. Nevertheless, the root causes for the observed TEC enhancements seen in the storm recovery phase are unknown and require further observations and model studies. Lei, Jiuhou; Huang, Fuqing; Chen, Xuetao; Zhong, Jiahao; Ren, Dexin; Wang, Wenbin; Yue, Xinan; Luan, Xiaoli; Jia, Mingjiao; Dou, Xiankang; Hu, Lianhuan; Ning, Baiqi; Owolabi, Charles; Chen, Jinsong; Li, Guozhu; Xue, Xianghui; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2018 YEAR: 2018 DOI: 10.1029/2017JA025166 |
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Seasonal Variation Analysis of Thermospheric Composition in TIMED/GUVI Limb Measurements Knowledge of thermospheric variability is essential to the understanding and forecasting of ionospheric behavior and space weather. As well, thermospheric density variability is a vital ingredient for prediction of space objects orbital changes and the lifetime of spacecraft. The Global UltraViolet Imager (GUVI) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite provides the first global dataset of thermosphere composition (O, N2 and O2 densities) and temperature vertical profiles from 2002-2007. Yue, Jia; Meier, Robert; Jian, Yongxiao; Yee, Jeng-Hwa; Wu, Dong; Russell, James; Wang, Wenbin; Burns, Alan; Published by: 2018 Triennial Earth-Sun Summit (TESS Published on: |
| 2017 |
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Impact of the lower thermospheric winter-to-summer residual circulation on thermospheric composition Gravity wave forcing near the mesopause drives a summer-to-winter residual circulation in the mesosphere and a reversed, lower thermospheric winter-to-summer residual circulation. We conducted modeling studies to investigate how this lower thermospheric residual circulation impacts thermospheric composition (O/N2). We found that the upwelling associated with the residual circulation significantly decreases O/N2 in winter and the downwelling in summer slightly increases O/N2. Consequently, the residual circulation reduces the summer-to-winter latitudinal gradient of O/N2, which causes the simulated latitudinal gradient of O/N2 to be more consistent with observations. The smaller summer-to-winter latitudinal gradient of O/N2 would decrease the ionosphere winter anomaly in model simulations, which would bring the simulated winter anomaly into better agreement with ionospheric observations. The lower thermospheric residual circulation may be a process that has been largely ignored but is very important to the summer-to-winter latitudinal gradients, as well as annual/semiannual variations in the thermosphere and ionosphere. Published by: Geophysical Research Letters Published on: 05/2017 YEAR: 2017 DOI: 10.1002/2017GL073361 |
| 2016 |
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This work estimates global-mean Kzz using Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics monthly global-mean CO2 profiles and a one-dimensional transport model. It is then specified as a lower boundary into the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). Results first show that global-mean CO2 in the mesosphere and lower thermosphere region has annual and semiannual oscillations (AO and SAO) with maxima during solstice seasons along with a primary maximum in boreal summer. Our calculated AO and SAO in global-mean CO2 are then modeled by AO and SAO in global-mean Kzz. It is then shown that our estimated global-mean Kzz is lower in magnitude than the suggested global-mean Kzz from Qian et al. (2009) that can model the observed AO and SAO in the ionosphere/thermosphere (IT) region. However, our estimated global-mean Kzz is similar in magnitude with recent suggestions of global-mean Kzz in models with explicit gravity wave parameterization. Our work therefore concludes that global-mean Kzz from global-mean CO2 profiles cannot model the observed AO and SAO in the IT region because our estimated global-mean Kzz may only be representing eddy diffusion due to gravity wave breaking. The difference between our estimated global-mean Kzz and the global-mean Kzz from Qian et al. (2009) thus represents diffusion and mixing from other nongravity wave sources not directly accounted for in the TIE-GCM lower boundary conditions. These other sources may well be the more dominant lower atmospheric forcing behind the AO and SAO in the IT region. Salinas, Cornelius; Chang, Loren; Liang, Mao-Chang; Yue, Jia; Russell, James; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2016 YEAR: 2016 DOI: 10.1002/2016JA023161 |
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In this paper, an ionospheric electron density reanalysis algorithm was used to generate global optimized electron density during the 17\textendash18 March 2013 geomagnetic storm by assimilating ~10 low Earth orbit satellites based and ~450 ground global navigation satellite system receiver-based total electron content into a background ionospheric model. The reanalyzed electron density could identify the large-scale ionospheric features quite well during storm time, including the storm-enhanced density, the positive ionospheric storm effect during the initial and main phases, and the negative ionospheric storm effect during the recovery phase. The simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model can reproduce similar large-scale ionospheric disturbances as seen in the reanalysis results. Both the reanalysis and simulations show long-lasting (\>17 h) daytime negative storm effect over the Asia sector as well as hemispheric asymmetry during the recovery phase. Detailed analysis of the Global Ultraviolet Imager-derived O/N2 ratio and model simulations indicate that the polar ward meridional wind disturbance, the downward E \texttimes B drift disturbance and O/N2 depletion might be responsible for the negative storm effect. The hemispheric asymmetry is mainly caused by the geomagnetic field line configuration, which could cause hemispheric asymmetry in the O/N2 depletion. Yue, Xinan; Wang, Wenbin; Lei, Jiuhou; Burns, Alan; Zhang, Yongliang; Wan, Weixing; Liu, Libo; Hu, Lianhuan; Zhao, Biqiang; Schreiner, William; Published by: Journal of Geophysical Research: Space Physics Published on: 11/2016 YEAR: 2016 DOI: 10.1002/jgra.v121.910.1002/2016JA022984 |
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Coherent seasonal, annual, and quasi-biennial variations in ionospheric tidal/SPW amplitudes In this study, we examine the coherent spatial and temporal modes dominating the variation of selected ionospheric tidal and stationary planetary wave (SPW) signatures from 2007 to 2013 FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) total electron content observations using multidimensional ensemble empirical mode decomposition (MEEMD) from the Hilbert-Huang Transform. We examine the DW1, SW2, DE3, and SPW4 components, which are driven by a variety of in situ and vertical coupling sources. The intrinsic mode functions (IMFs) resolved by MEEMD analysis allows for the isolation of the dominant modes of variability for prominent ionospheric tidal/SPW signatures in a manner not previously used, allowing the effects of specific drivers to be examined individually. The time scales of the individual IMFs isolated for all tidal/SPW signatures correspond to a semiannual variation at equatorial ionization anomaly (EIA) latitudes maximizing at the equinoxes, as well as annual oscillations at the EIA crests and troughs. All tidal/SPW signatures show one IMF isolating an ionospheric quasi-biennial oscillation (QBO) in the equatorial latitudes maximizing around January of odd-numbered years. This total electron content QBO variation is in phase with a similar QBO variation isolated in both the Global Ultraviolet Imager (GUVI) zonal mean column O/N2 density ratio (ΣO/N2) and the F10.7 solar radio flux index around solar maximum, while showing temporal variation more similar to that of GUVI ΣO/N2 during the time around the 2008/2009 extended solar minimum. These results point to both quasi-biennial variations in solar irradiance and thermosphere/ionosphere composition as a generation mechanism for the ionospheric QBO. Chang, Loren; Sun, Yan-Yi; Yue, Jia; Wang, Jack; Chien, Shih-Han; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2016 YEAR: 2016 DOI: 10.1002/2015JA022249 |
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Topside ionospheric total electron content (TEC) observations from multiple low-Earth orbit (LEO) satellites have been used to investigate the local time, altitudinal, and longitudinal dependence of the topside ionospheric storm effect during both the main and recovery phases of the March 2015 geomagnetic storm. The results of this study show, for the first time, that there was a persistent topside TEC depletion that lasted for more than 3 days after the storm main phase at most longitudes, except in the Pacific Ocean region, where the topside TECs during the storm recovery phase were comparable to the quiet time ones. The observed depletion in the topside ionospheric TEC was relatively larger at higher altitudes in the evening sector and greater at local times closer to midnight. Moreover, the topside TEC patterns observed by MetOp-A (832 km) were different from those seen by other LEO satellites with lower orbital altitudes during the storm main phase and at the beginning of the recovery phase, especially in the evening sector. This suggests that the physical processes that control the storm time behavior of topside ionospheric response to storms are altitude-dependent. Zhong, Jiahao; Wang, Wenbin; Yue, Xinan; Burns, Alan; Dou, Xiankang; Lei, Jiuhou; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2016 YEAR: 2016 DOI: 10.1002/2016JA022469 |
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This work estimates global‐mean K zz using Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics Salinas, Cornelius; Chang, Loren; Liang, Mao-Chang; Yue, Jia; , Russell; Mlynczak, Martin; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2016 DOI: 10.1002/2016JA023161 |
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Profiles of ionospheric storm-enhanced density during the 17 March 2015 great storm Liu, Jing; Wang, Wenbin; Burns, Alan; Yue, Xinan; Zhang, Shunrong; Zhang, Yongliang; Huang, Chaosong; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2015 |
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Explaining solar cycle effects on composition as it relates to the winter anomaly The solar cycle variation of\ F2\ region winter anomaly is related to solar cycle changes in the latitudinal winter-to-summer difference of O/N2. Here we use the National Center for Atmospheric Research\textendashGlobal Mean Model to develop a concept of why the latitudinal winter-to-summer difference of O/N2\ varies with solar cycle. The main driver for these seasonal changes in composition is vertical advection, which is expressed most simply in pressure coordinates. Meridional winds do not change over the solar cycle, so the vertical winds should also not change. The other component of vertical advection is the vertical gradient of composition. Is there any reason that this should change? At solar maximum vertical temperature gradients between 100 and 200 km altitude are strong, whereas they are weak at solar minimum. To maintain the same pressure, the weak vertical temperature gradients at solar minimum must be balanced by weak density gradients and the strong temperature gradients at solar maximum must be balanced by strong density gradients to obtain the same pressure profile. Changes in the vertical density gradients are species dependent: heavy species change more and light species change less than the average density change. Hence, vertical winds act on stronger O/N2\ gradients at solar maximum than they do at solar minimum, and a stronger winter-to-summer difference of O/N2\ occurs at solar maximum compared with solar minimum. Burns, A.; Solomon, S.; Wang, W.; Qian, L.; Zhang, Y.; Paxton, L.; Yue, X.; Thayer, J.; Liu, H.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2015 YEAR: 2015 DOI: 10.1002/2015JA021220 |
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Ionosphere equatorial ionization anomaly observed by GPS radio occultations during 2006--2014 A large number of Global Position System (GPS) radio occultation (RO) observations have been accumulated in the University Corporation for Atmospheric Research (UCAR) Constellation Observation System for Meteorology, Ionosphere and Climate (COSMIC) Data Analysis and Archive Center (CDAAC) especially since the launch of COSMIC mission. This study made use of these RO data to study the morphology of ionosphere equatorial ionization anomaly (EIA) statistically during 2006\textendash2014. The ionospheric peak density (NmF2) and peak height (hmF2) derived from the RO electron density profiles as well as the derived magnetic latitude of both crests and trough, the trough width, and the crest-to-trough ratio (CTR) of NmF2 are analyzed systematically. The corresponding seasonal, local time, and solar activity variations and the hemispheric asymmetry are identified and discussed. Most morphology agree well with previous studies and could be explained by the corresponding variations of neutral wind/composition and ExB vertical drift. We also found some interesting features. During May\textendashAugust, magnetic latitude of the trough could be up to ~5\textdegree north of the equator especially around noontime, and the local time difference corresponding best developed EIA between both hemispheres could be up to ~6\ h. Both crests even move equator-ward with the increase of solar activity in the morning sector except June solstice. Yue, Xinan; Schreiner, William; Kuo, Ying-Hwa; Lei, Jiuhou; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2015 YEAR: 2015 DOI: 10.1016/j.jastp.2015.04.004 |
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This paper presents an epoch analysis of global ionosphere responses to recurrent geomagnetic activity during 79 corotating interaction region (CIR) events from 2004 to 2009. The data used were GPS total electron content (TEC) data from the Madrigal Database at the Massachusetts Institute of Technology Haystack Observatory and the electron density (Ne) data obtained from CHAllenging Minisatellite Payload (CHAMP) observations. The results show that global ionosphere responses to CIR events have some common features. In high and middle latitudes, the total electron content (TEC) showed a significant positive response (increased electron densities) in the first epoch day. A negative TEC response occurred at high latitudes of the American sector following the positive response. The CHAMP Ne showed a daytime positive response in all latitudes and a nighttime negative response in the subauroral region. These negative TEC and Ne responses were found to be related to thermospheric composition (O/N2) changes during the storms. At all latitudes, the maximum of the TEC positive effect always occurred at 2\textendash6 h after the CIR starting during local daytime and 10\textendash18 h later for the CIR onset during local nighttime. Case studies indicate that the TEC and Ne positive response had a strong dependence on the southward component (Bz) of the interplanetary magnetic field and solar wind speed. This suggests that penetration electric fields that were associated with changes in solar winds might play a significant role in the positive ionospheric response to storms. During the recovery time of the CIR-produced geomagnetic activity, the TEC positive disturbance at low latitudes sometimes could last for 2\textendash4 days, whereas at middle to high latitudes the disturbance lasted only for 1 day in most cases. A comparison of the ionospheric responses between the American, European and Asian sectors shows that the ionosphere response in the North American sector was stronger than that in the other two regions. The response of foF2 to the CIR events in middle to high latitudes showed a negative response for 2\textendash3 days after the first epoch day. This is different from the response of TEC, which was mostly positive during the same period of time. Chen, Yanhong; Wang, Wenbin; Burns, Alan; Liu, Siqing; Gong, Jiancun; Yue, Xinan; Jiang, Guoying; Coster, Anthea; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2015 YEAR: 2015 DOI: 10.1002/2014JA020657 CIR events; epoch study; Ionospheric response; recurrent geomagnetic activity |
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Longitudinal variations of the nighttime E layer electron density in the auroral zone Longitudinal variations of the nighttime E layer electron density (21:00\textendash03:00 magnetic local time) in the auroral zone are investigated, and their sources are discussed in terms of auroral precipitation and solar radiation. The electron density data used in this study are retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation observations during 2006\textendash2009 under quiet geomagnetic activity (Kp <= 3) and solar minimum conditions. The main conclusions of this study are as follows: (1) the nighttime E layer electron density had pronounced longitudinal variations in the auroral zone. These variations depended on season and had large hemispheric asymmetry for all seasons. In winter, relatively larger electron density was located in 120\textendash310\textdegree magnetic longitude (MLON) in the northern hemisphere and in 170\textendash360\textdegree MLON in the southern hemisphere, and greater maximum density occurred in the northern hemisphere than in the southern one. In summer and equinox, the longitudinal asymmetry was greater in the southern hemisphere. (2) The peaks of the E layer electron density along latitude generally occurred between 65\textdegree and 70\textdegree magnetic latitude in the auroral zone in all seasons for both hemispheres except for the sunlit sector of the southern summer. (3) The greater electron density in local winter in the auroral zone was generally associated with the more intense auroral precipitation intensity at roughly the same longitude, whereas the longitudinal patterns of the electron density were under the combined impact of both auroral precipitation and solar radiation in the local summer and equinoxes. Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2015 YEAR: 2015 DOI: 10.1002/2014JA020610 auroral E layer; hemispheric asymmetry; longitudinal variations; Seasonal variations |
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In the current work, temperature and wind data from the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during the years 2002\textendash2007 were used to describe the seasonal variations of the westward propagating 6.5-day planetary wave in the mesosphere and lower thermosphere (MLT). Thermospheric composition data from the TIMED satellite and ionospheric total electron content (TEC) from the International Global Navigation Satellite System (GNSS) Service were then employed to carry out two case studies on the effect of this dissipating wave on the thermosphere/ionosphere. In both cases, there were westward anomalies of ~ 30\textendash40 m s-1\ in zonal wind in the MLT region that were caused by momentum deposition of the 6.5-day wave, which had peak activity during equinoxes. The westward zonal wind anomalies led to extra poleward meridional flows in both hemispheres. Meanwhile, there were evident overall reductions of thermospheric column density O / N2\ ratio and ionospheric TEC with magnitudes of up to 16\textendash24 \% during these two strong 6.5-day wave events. Based on the temporal correlation between O / N2\ and TEC reductions, as well as the extra poleward meridional circulations associated with the 6.5-day waves, we conclude that the dissipative 6.5-day wave in the lower thermosphere can cause changes in the thermosphere/ionosphere via the mixing effect, similar to the quasi-two-day wave (QTDW) as predicted by Yue and Wang (2014). Gan, Q.; Yue, J.; Chang, L.; Wang, W.; Zhang, S.; Du, J.; Published by: Annales Geophysicae Published on: 01/2015 YEAR: 2015 DOI: 10.5194/angeo-33-913-2015 |
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Longitudinal variations of the nighttime E layer electron density in the auroral zone Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Azeem, Irfan; Yue, Jia; Hoffmann, Lars; Miller, Steven; Straka, William; Crowley, Geoff; Published by: Geophysical research letters Published on: |
| 2014 |
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Height-integrated Pedersen conductivity in both E and F regions from COSMIC observations Altitudinal distribution of Joule heating is very important to the thermosphere and ionosphere, which is roughly proportional to the Pedersen conductance at high latitudes. Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites observations from 2008 to 2011, the height-integrated Pedersen conductivities in both E (100\textendash150\ km) and F (150\textendash600\ km) regions and their ratio γPγP (∑PE/∑PF∑PE/∑PF) have been calculated. The result shows that the maximum ratio in the northern summer hemisphere is ~5.5, which is smaller than that from the Thermosphere\textendashIonosphere\textendashElectrodynamics General Circulation Model (TIE-GCM v1.94) simulation (~9). This indicates that the energy inputs into the F region may be underestimated in the model. The seasonal variations of the ratio have been investigated for both hemispheres, and an interhemispheric asymmetry has been identified. The variational trend of the ratio is similar in both hemispheres, which reaches minimum at local summer and maximum at local winter. However, the difference of the ratio from local summer to local winter in the southern hemisphere is larger than that in the northern hemisphere. Sheng, Cheng; Deng, Yue; Yue, Xinan; Huang, Yanshi; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 08/2014 YEAR: 2014 DOI: 10.1016/j.jastp.2013.12.013 COSMIC; Interhemispheric asymmetry; Joule heating; Pedersen conductivity |
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Dissipating planetary waves in the mesosphere/lower thermosphere (MLT) region may cause changes in the background dynamics of that region, subsequently driving variability throughout the broader thermosphere/ionosphere system via mixing due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during the northern winter in the context of the quasi two day wave (QTDW)\textemdasha planetary wave that recurrently grows to large amplitudes from the summer MLT during the postsolstice period. Six distinct QTDW events between 2003 and 2011 are identified in the MLT using Sounding of the Atmosphere using Broadband Emission Radiometry temperature observations. Concurrent changes to the background zonal winds, zonal mean column O/N2 density ratio, and ionospheric total electron content (TEC) are examined using data sets from Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer, Global Ultraviolet Imager, and Global Ionospheric Maps, respectively. We find that in the 5\textendash10 days following a QTDW event, the background zonal winds in the MLT show patterns of eastward and westward anomalies in the low and middle latitudes consistent with past modeling studies on QTDW-induced mean wind forcing, both below and at turbopause altitudes. This is accompanied by potentially related decreases in zonal mean thermospheric column O/N2, as well as to low-latitude TECs. The recurrent nature of the above changes during the six QTDW events examined point to an avenue for vertical coupling via background dynamics and chemistry of the thermosphere/ionosphere not previously observed. Chang, Loren; Yue, Jia; Wang, Wenbin; Wu, Qian; Meier, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.610.1002/2014JA019936 composition; Ionosphere; mesosphere; quasi two day wave; thermosphere |
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Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity and solar EUV radiation have been investigated using neutral temperature data observed by the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) instrument and numerical experiments by the NCAR-TIME-GCM (National Center for Atmospheric Research\textendashthermosphere-ionosphere-mesosphere electrodynamics\textendashgeneral circulation model). The TIMED/SABER data analyzed were for the period from 2002 to 2007 during the declining phase of solar cycle 23. The observations show that the zonal mean temperature in the lower thermosphere oscillated with periods of near 9 and 13.5 days in the height range of 100\textendash120 km. These oscillations were more strongly correlated with the recurrent geomagnetic activity than with the solar EUV variability of the same periods. The 9 day and 13.5 day oscillations of lower thermospheric temperature had greater amplitudes at high latitudes than at low latitudes; they also had larger amplitudes at higher altitudes, and the oscillations could penetrate down to ~105 km, depending on the strength of the recurrent geomagnetic activity for a particular time period. The data further show that the periodic responses of the lower thermospheric temperature to recurrent geomagnetic activity were different in the two hemispheres. In addition, numerical experiments have been carried out using the NCAR-TIME-GCM to investigate the causal relationship between the temperature oscillations and the geomagnetic activity and solar EUV variations of the same periods. Model simulations showed the same periodic oscillations as those seen in the observations when the real geomagnetic activity index, Kp, was used to drive the model. These numerical results show that recurrent geomagnetic activity is the main cause of the 9 day and 13.5 day variations in the lower thermosphere temperature, and the contribution from solar EUV variations is minor. Furthermore, we also found that consecutive coronal mass ejection events could cause long-duration enhancements in the lower thermospheric temperature that strengthen the 9 day and 13.5 day signals, and this kind of phenomenon mostly occurred between 2002 and 2005 during the declining phase of solar cycle 23. Jiang, Guoying; Wang, Wenbin; Xu, JiYao; Yue, Jia; Burns, Alan; Lei, Jiuhou; Mlynczak, Martin; Rusell, James; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.610.1002/2013JA019406 13.5 day variation; 9 day variation; Joule heating; lower thermospheric temperature; recurrent geomagnetic activity; solar EUV radiation |
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On the solar cycle variation of the winter anomaly Constellation Observing System for Meteorology, Ionosphere and Climate, Ionosonde, and Global Ultraviolet Imager data have been used to investigate the solar cycle changes in the winter anomaly (the winter anomaly is defined as the enhancement of the F2 peak electron density in the winter hemisphere over that in the summer hemisphere) in the last solar cycle. There is no winter anomaly in solar minimum, and an enhancement of about 50\% in winter over summer ones on the same day of the year at solar maximum. This solar cycle variation in the winter anomaly is primarily due to greater winter to summer differences of [O]/[N2] in solar maximum than in solar minimum, with a secondary contribution from the effects of temperature on the recombination coefficient between O+ and the molecular neutral gas. The greater winter increases in electron density in the Northern Hemisphere than in the Southern Hemisphere appear to be related to the greater annual variation of [O]/[N2] in the north than in the south. Burns, A.; Wang, W.; Qian, L.; Solomon, S.; Zhang, Y.; Paxton, L.; Yue, X.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.610.1002/2013JA019552 |
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Longitudinal and Hemispheric Variations of Nighttime E-Layer Electron Density in the Auroral Zone Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan; Published by: Published on: |
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Predictability and Ensemble Modeling of the Space-Atmosphere Interaction Region Matsuo, Tomoko; Fuller-Rowell, Timothy; Akmaev, Rashid; Wang, Houjun; Fang, Tzu-Wei; Ide, Kayo; Kleist, Daryl; Whitaker, JS; Yue, Xinan; Codrescu, Mihail; , others; Published by: Published on: |
| 2013 |
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On the fast zonal transport of the STS-121 space shuttle exhaust plume in the lower thermosphere Meier et al. (2011) reported rapid eastward transport of the STS-121 space shuttle (launch: July 4, 2006) main engine plume in the lower thermosphere, observed in hydrogen Lyman α images by the GUVI instrument onboard the TIMED satellite. In order to study the mechanism of the rapid zonal transport, diagnostic tracer calculations are performed using winds from the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM) simulation of July, 2006. It is found that the strong eastward jet at heights of 100\textendash110\ km, where the exhaust plume was deposited, results in a persistent eastward tracer motion with an average velocity of 45\ m/s. This is generally consistent with, though faster than, the prevailing eastward shuttle plume movement with daily mean velocity of 30\ m/s deduced from the STS-121 GUVI observation. The quasi-two-day wave (QTDW) was not included in the numerical simulation because it was found not to be large. Its absence, however, might be partially responsible for insufficient meridional transport to move the tracers away from the fast jet in the simulation. The current study and our model results from Yue and Liu (2010) explain two very different shuttle plume transport scenarios (STS-121 and STS-107 (launch: January 16, 2003), respectively): we conclude that lower thermospheric dynamics is sufficient to account for both very fast zonal motion (zonal jet in the case of STS-121) and very fast meridional motion to polar regions (large QTDW in the case of STS-107). Yue, Jia; Liu, Han-Li; Meier, R.R.; Chang, Loren; Gu, Sheng-Yang; , Russell; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-03-2013 YEAR: 2013 DOI: 10.1016/j.jastp.2012.12.017 |
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Global Navigation Satellite System (GNSS) based radio occultation (RO) technique has shown powerful ability in ionospheric electron density profiling in the past decade. The most frequently used Abel inversion method in electron density retrieval has some biases because of the used spherical symmetry assumption. Our previous series simulations and evaluations mainly concentrated in the middle and low latitude regions have shown some systematical bias especially in lower altitude of low latitude region. However, the RO derived electron density quality in the high latitude and polar region is rarely investigated and not quantitatively clear yet. In this study, the Abel inversion error over high latitude and polar regions are systematically investigated for the first time based on NCAR-TIEGCM simulations and real data evaluations. The TIMED data driven NCAR-TIEGCM modeled electron density during 2008 are used to simulate the COSMIC RO events. The Abel inversion error can then be estimated by comparing Abel retrievals from TIEGCM simulated occultation with the original TIEGCM simulations. The Abel inversion can reproduce the season, altitude, latitude, and local time variation patterns of electron density and auroral zone electron density nighttime enhancement well in high latitude and polar region. The Abel inversion tends to underestimate the electron density in the auroral zone and overestimate it on both the equatorward and poleward sides of the auroral zone. As simulated by the TIEGCM model, the significant relative error (\>25\%) mainly occurs in lower altitude (\<250\ km) inside and around auroral zone region. Above 250\ km, the relative error mostly is less than 25\%. Specifically, RMSE (root mean square error) of NmF2 error from simulation is \~8.5\%. The Abel error under real ionosphere situation would be worse because the ionosphere could be more complicated and noisier than the model simulation. The error distribution and its seasonal, local time and latitude variations can be explained by the spherical symmetry assumption used in the Abel inversion associated with the corresponding ionospheric electron density variations. The comparisons between PFISR and COSMIC RO electron density during 2007\textendash2011 and some previous validation studies agree well with our simulation results. We hope these results can stimulate more studies in high latitude ionospheric research using RO data. Yue, Xinan; Schreiner, William; Kuo, Ying-Hwa; Wu, Qian; Deng, Yue; Wang, Wenbin; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 06/2013 YEAR: 2013 DOI: 10.1016/j.jastp.2013.03.009 Abel inversion; AURORA; COSMIC; Electron density; GNSS radio occultation; TIEGCM |
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The global configuration of the geomagnetic field shows that the maximum east-west difference in geomagnetic declination of northern middle latitude lies in the US region (~32\textdegree), which produces the significant ionospheric east-west coast difference in terms of total electron content first revealed by Zhang et al. (2011). For verification, it is valuable to investigate this feature over the Far East area, which also shows significant geomagnetic declination east-west gradient but smaller (~15\textdegree) than that of the US. The current study provides evidence of the longitudinal change supporting the thermospheric zonal wind mechanism by examining the climatology of peak electron density (NmF2), electron density (Ne) of different altitudes in the Far East regions with a longitude separation of up to 40\textendash60\textdegree based on ground ionosonde and space-based measurements. Although the east-west difference (Rew) over the Far East area displays a clear diurnal variation similar to the US feature, that is negative Rew (West Ne \> East Ne) in the noon and positive at evening-night, the observational results reveal more differences including: (1) The noontime negative Rew is most pronounced in April\textendashJune while in the US during February\textendashMarch. Thus, for the late spring and summer period negative Rew over the Far East region is more significant than that of the US. (2) The positive Rew at night is much less evident than in the US, especially without winter enhancement. (3) The magnitude of negative Rew tends to enhance toward solar maximum while in the US showing anticorrelation with the solar activity. The altitude distribution of pronounced negative difference (300\textendash400 km) moves upward as the solar flux increases and hence produces the different solar activity dependence at different altitude. The result in the paper is not simply a comparison corresponding to the US results but raises some new features that are worth further studying and improve our current understanding of ionospheric longitude difference at midlatitude. Zhao, Biqiang; Wang, Min; Wang, Yungang; Ren, Zhipeng; Yue, Xinan; Zhu, Jie; Wan, Weixing; Ning, Baiqi; Liu, Jing; Xiong, Bo; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2013 YEAR: 2013 DOI: 10.1029/2012JA018235 geomagnetic declination; longitudinal variation; midlatitude ionosphere |
| 2010 |
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Fast meridional transport in the lower thermosphere by planetary-scale waves Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-12-2010 YEAR: 2010 DOI: 10.1016/j.jastp.2010.10.001 |
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Correlation between the ionospheric WN4 signature and the upper atmospheric DE3 tide Wan, W.; Xiong, J.; Ren, Z.; Liu, L.; Zhang, M.-L.; Ding, F.; Ning, B.; Zhao, B.; Yue, X.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2010JA015527 |
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Ionosphere around equinoxes during low solar activity Liu, Libo; He, Maosheng; Yue, Xin\textquoterightan; Ning, Baiqi; Wan, Weixing; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2010JA015318 |
| 2008 |
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Previous ground observations have revealed a correlation that exists between equatorial plasma bubbles, evening equatorial ionization anomaly (EIA), and prereversal E × B drift velocity using latitudinal arrays of ionospheric sounders, such as in the Indian and American regions. Besides the ground measurements, the space-based observations also provide a convenient way to study the global-scale variations. Li, Guozhu; Ning, Baiqi; Liu, Libo; Zhao, Biqiang; Yue, Xinan; Su, S-Y; Venkatraman, Sarita; Published by: Radio Science Published on: YEAR: 2008 DOI: 10.1029/2007RS003760 |
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