Bibliography
|
Notice:
|
Found 494 entries in the Bibliography.
Showing entries from 251 through 300
| 2013 |
|
One important characteristic of longitudinal variability of the ionosphere is the global wavenumber-4 signature. Recent investigations have focused mainly on the climatological pattern during daytime and evening sectors. We investigate the day-to-day variability of the wavenumber-4 structure of the longitudinal ionospheric density distribution using the global total electron content (TEC) measurements from Global Positioning Systems receivers on the ground. The quiet time (Kp <= 3) day-to-day occurrence of the wavenumber-4 is obtained during periods of low solar flux conditions for the years 2008 and 2009. We find that the wavenumber-4 structure occurs at all local time sectors; however, the daytime TEC wavenumber-4 structures are clearer and can persist until the midnight hours. The most significant occurrence is observed during the 1000\textendash2400 LT sector while the minimum number of wavenumber-4 structure is observed between the 0400 and 0600 LT sector. Around the nighttime sector, more wavenumber-4 occurrence is observed during the premidnight sector than the postmidnight hours. The seasonal occurrence probability of the wavenumber-4 pattern is at a maximum during the March\textendashApril equinox and June\textendashJuly solstice. December\textendashJanuary is the period when the wavenumber-4 occurrence is less dominant than the rest of the year. Published by: Journal of Geophysical Research: Space Physics Published on: 04/2013 YEAR: 2013 DOI: 10.1002/jgra.50241 day-to-day; Ionosphere; longitudinal variability; TEC; wavenumber-4 |
|
[1]\ Measurements of the Earth\textquoterights low latitude thermosphere returned by the ionization gauge on the Streak mission are reported and discussed. The measurements are of the amount of gas rammed into the sensor by its passage through the thermospheric medium. They were obtained in the dusk sector in the altitude range 130\textendash330 km and are shown to be strongly structured by the geomagnetic field. Similarities to the structure of the equatorial ionization anomaly are discussed. The structure is interpreted as being due to rapid (several hundred meters per second) meridional winds having an antisymmetric pattern with respect to the geomagnetic equator. The measurements are interpreted in light of results from other missions and are shown to fit well with ideas based on complementary measurements from the Dynamics Explorer 2 mission discussed as the Equatorial Temperature and Wind Anomaly. Several features of these winds are described and discussed, including their altitude dependence, how they form convection cells that extend to high latitude, and how the wind amplitudes vary with geographic longitude with an apparent wavenumber one variation. The latter characteristic is shown to be consistent with being the signature of tidal variations observed by others. Approximate calculations utilizing published values for the pertinent parameters are used to show that heating from the dissipation due to ion drag within the ionospheric F region is a dominant driver of the inferred winds. Clemmons, J.; Walterscheid, R.; Christensen, A.; Bishop, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2013 YEAR: 2013 DOI: 10.1029/2012JA017661 |
|
Solar cycle dependence of the seasonal variation of auroral hemispheric power Although much has been done on the hemispheric asymmetry (or seasonal variations) of auroral hemispheric power (HP), the dependence of HP hemispheric asymmetry on solar cycle has not yet been studied. We have analyzed data during 1979\textendash2010 and investigated the dependence of HP hemispheric asymmetry/seasonal variation for the whole solar cycle. Here we show that (1) the hemispheric asymmetry of HP is positively correlated to the value of solar F10.7 with some time delay; (2) it is closely related to the coupling function between the solar wind and magnetosphere; and (3) the winter hemisphere receives more auroral power than the summer hemisphere for K p\~0 to 6. The statistic results can be partly understood in the framework of the ionospheric conductivity feedback model. The similarity and differences between our results and previous results are discussed in the paper. Zheng, Ling; Fu, SuiYan; Zong, QuiGang; Parks, George; Wang, Chi; Chen, Xi; Published by: Chinese Science Bulletin Published on: 02/2013 YEAR: 2013 DOI: 10.1007/s11434-012-5378-6 auroral power; coupling function; hemispheric asymmetry; precipitation; solar cycle |
|
Solar cycle dependence of the seasonal variation of auroral hemispheric power Although much has been done on the hemispheric asymmetry (or seasonal variations) of auroral hemispheric power (HP), the dependence of HP hemispheric asymmetry on solar cycle has not yet been studied. We have analyzed data during 1979\textendash2010 and investigated the dependence of HP hemispheric asymmetry/seasonal variation for the whole solar cycle. Here we show that (1) the hemispheric asymmetry of HP is positively correlated to the value of solar F10.7 with some time delay; (2) it is closely related to the coupling function between the solar wind and magnetosphere; and (3) the winter hemisphere receives more auroral power than the summer hemisphere for K p\~0 to 6. The statistic results can be partly understood in the framework of the ionospheric conductivity feedback model. The similarity and differences between our results and previous results are discussed in the paper. Zheng, Ling; Fu, SuiYan; Zong, QuiGang; Parks, George; Wang, Chi; Chen, Xi; Published by: Chinese Science Bulletin Published on: 02/2013 YEAR: 2013 DOI: 10.1007/s11434-012-5378-6 auroral power; coupling function; hemispheric asymmetry; precipitation; solar cycle |
|
A study of the response of the thermosphere and ionosphere to sudden stratospheric warmings (SSWs) which occurred in January of 2008 and 2009 is presented. The Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere (GSM TIP) developed in the West Department of IZMIRAN was a theoretical basis for this study. A comparison of the simulation results of the thermosphere-ionosphere response to SSW events with the observational data over Irkutsk and also with theoretical and experimental studies carried out during the recent years is performed. SSW events were modeled by setting disturbances in the neutral temperature and density at the lower boundary of the GSM TIP model (80 km above the Earth\textquoterights surface). It is shown that the disturbances related to SSW lead to substantial global effects in the thermosphere and ionosphere. The analysis of the experimental data showed that, in spite of very similar solar and geophysical conditions on the background of which two considered stratospheric warming events happened, the occurring disturbances in temperature at heights of the mesosphere and lower thermosphere differ substantially from each other, although some common regularities still take place especially at heights of the ionospheric F region. Klimenko, M.; Klimenko, V.; textquoterightkov, Yu.; Bessarab, F.; Karpov, I.; Ratovsky, K.; Chernigovskaya, M.; Published by: Cosmic Research Published on: 01/2013 YEAR: 2013 DOI: 10.1134/S001095251301005X |
|
Multiple neutral density measurements in the lower thermosphere with cold-cathode ionization gauges Cold-cathode ionization gauges were used for rocket-borne measurements of total neutral density and temperature in the aurorally forced lower thermosphere between 90 and 200\ km. A commercial gauge was adapted as a low-cost instrument with a spherical antechamber for measurements in molecular flow conditions. Three roll-stabilized payloads on different trajectories each carried two instruments for measurements near the ram flow direction along the respective upleg and downleg segments of a flight path, and six density profiles were obtained within a period of 22\ min covering spatial separations up to 200\ km. The density profiles were integrated below 125\ km to yield temperatures. The mean temperature structure was similar for all six profiles with two mesopause minima near 110 and 101\ km, however, for the downleg profiles, the upper minimum was warmer and the lower minimum was colder by 20\textendash30\ K indicating significant variability over horizontal scales of 100\textendash200\ km. The upper temperature minimum coincided with maximum horizontal winds speeds, exceeding 170\ m/s. Lehmacher, G.A.; Gaulden, T.M.; Larsen, M.F.; Craven, J.D.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 01/2013 YEAR: 2013 DOI: 10.1016/j.jastp.2012.11.002 Instruments and techniques; Pressure density and temperature; thermosphere |
|
Retrieving ionospheric electron density profile from FUV spectral remote sensing measurements WANG, Jing; Tang, Yi; ZHANG, Zhi-Ge; ZHENG, Xu-Li; Ni, Guo-qiang; Published by: Chinese Journal of Geophysics Published on: |
|
A Quality Assessment Method for Retrieved O/N\_2 Images from FUV Remote Sensing WANG, Jing; Tang, Yi; Peng, Sheng-feng; ZHENG, Xu-Li; Ni, Guo-qiang; Published by: Infrared Published on: |
|
Kinrade, Joe; Mitchell, Cathryn; Paxton, Larry; Bust, Gary; Published by: Published on: |
|
Zimmerman, MI; Hsieh, SW; Brandt, PC; Vandegriff, JD; Stephens, GK; Toigo, AD; Keika, K; Kusterer, MB; DeMajistre, R; Published by: Published on: |
|
The global positioning system (GPS) phase scintillation caused by highlatitude ionospheric irregularities during an intense high-speed stream (HSS) of the solar wind from April 29 to May 5, 2011, was observed using arrays of GPS ionospheric scintillation and total electron content monitors in the Arctic and Antarctica. The one-minute phase-scintillation index derived from the data sampled at 50 Hz was complemented by a proxy index (delta phase rate) obtained from 1-Hz GPS data. The scintillation occurrence coincided with the aurora borealis and aurora australis observed by an all-sky imager at the South Pole, and by special sensor ultraviolet scanning imagers on board satellites of the Defense Meteorological Satellites Program. The South Pole (SP) station is approximately conjugate with two Canadian High Arctic Ionospheric Network stations on Baffin Island, Canada, which provided the opportunity to study magnetic conjugacy of scintillation with support of riometers and magnetometers. The GPS ionospheric pierce points were mapped at their actual or conjugate locations, along with the auroral emission over the South Pole, assuming an altitude of 120 km. As the aurora brightened and/or drifted across the field of view of the all-sky imager, sequences of scintillation events were observed that indicated conjugate auroras as a locator of simultaneous or delayed bipolar scintillation events. In spite of the greater scintillation intensity in the auroral oval, where phase scintillation sometimes exceeded 1 radian during the auroral break-up and substorms, the percentage occurrence of moderate scintillation was highest in the cusp. Interhemispheric comparisons of bipolar scintillation maps show that the scintillation occurrence is significantly higher in the southern cusp and polar cap. Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others; Published by: Annals of Geophysics Published on: |
|
The global positioning system (GPS) phase scintillation caused by highlatitude ionospheric irregularities during an intense high-speed stream (HSS) of the solar wind from April 29 to May 5, 2011, was observed using arrays of GPS ionospheric scintillation and total electron content monitors in the Arctic and Antarctica. The one-minute phase-scintillation index derived from the data sampled at 50 Hz was complemented by a proxy index (delta phase rate) obtained from 1-Hz GPS data. The scintillation occurrence coincided with the aurora borealis and aurora australis observed by an all-sky imager at the South Pole, and by special sensor ultraviolet scanning imagers on board satellites of the Defense Meteorological Satellites Program. The South Pole (SP) station is approximately conjugate with two Canadian High Arctic Ionospheric Network stations on Baffin Island, Canada, which provided the opportunity to study magnetic conjugacy of scintillation with support of riometers and magnetometers. The GPS ionospheric pierce points were mapped at their actual or conjugate locations, along with the auroral emission over the South Pole, assuming an altitude of 120 km. As the aurora brightened and/or drifted across the field of view of the all-sky imager, sequences of scintillation events were observed that indicated conjugate auroras as a locator of simultaneous or delayed bipolar scintillation events. In spite of the greater scintillation intensity in the auroral oval, where phase scintillation sometimes exceeded 1 radian during the auroral break-up and substorms, the percentage occurrence of moderate scintillation was highest in the cusp. Interhemispheric comparisons of bipolar scintillation maps show that the scintillation occurrence is significantly higher in the southern cusp and polar cap. Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others; Published by: Annals of Geophysics Published on: |
|
Published by: Space Research Published on: |
|
Comparison of Ionospheric and Thermospheric Effects During Two High Speed Stream Events Verkhoglyadova, OP; Tsurutani, B; Mannucci, AJ; Paxton, L; Mlynczak, MG; Hunt, LA; Echer, E; Published by: Published on: |
|
The Geospace Dynamics Observatory; a mission of discovery for Geospace Spann, JF; Paxton, Larry; Burch, JL; Reardon, Patrick; Krause, Habash; Gallagher, DL; Hopkins, Randall; Published by: Published on: |
|
Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others; Published by: Annals of Geophysics Published on: |
|
Prikryl, Paul; Zhang, Yongliang; Ebihara, Yusuke; Ghoddousi-Fard, Reza; Jayachandran, Periyadan; Kinrade, Joe; Mitchell, Cathryn; Weatherwax, Allan; Bust, Gary; Cilliers, Pierre; , others; Published by: Annals of Geophysics Published on: |
| 2012 |
|
Thermosphere--ionosphere coupling in response to recurrent geomagnetic activity Mukhtarov, Plamen; Pancheva, Dora; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-12-2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.02.013 |
|
Longitudinal distribution of O2 nightglow brightness observed by TIEMD/SABER satellite Gao, Hong; Nee, JanBai; Chen, GuangMing; Published by: Science China Technological Sciences Published on: Jan-05-2012 YEAR: 2012 DOI: 10.1007/s11431-012-4802-0 |
|
Equinoctial asymmetry in solar activity variations of NmF2 and TEC Chen, Y.; Liu, L.; Wan, W.; Ren, Z.; Published by: Annales Geophysicae Published on: Jan-01-2012 YEAR: 2012 DOI: 10.5194/angeo-30-613-2012 |
|
Sojka, J.; David, M.; Schunk, R.; Heelis, R.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017000 |
|
Hecht, J.; Mulligan, T.; Correira, J.; Clemmons, J.; Strickland, D.; Walterscheid, R.; Conde, M.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017146 |
|
Hecht, J.; Mulligan, T.; Correira, J.; Clemmons, J.; Strickland, D.; Walterscheid, R.; Conde, M.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017146 |
|
Response of low-latitude ionosphere to medium-term changes of solar and geomagnetic activity Kutiev, Ivan; Otsuka, Yuichi; Pancheva, Dora; Heelis, Rod; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2012JA017641 |
|
Response of low-latitude ionosphere to medium-term changes of solar and geomagnetic activity Kutiev, Ivan; Otsuka, Yuichi; Pancheva, Dora; Heelis, Rod; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2012JA017641 |
|
Superposed epoch analyses of thermospheric response to CIRs: Solar cycle and seasonal dependencies Liu, Jing; Liu, Libo; Zhao, Biqiang; Lei, Jiuhou; Thayer, Jeffrey; McPherron, Robert; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017315 |
|
Bright polar mesospheric clouds formed by main engine exhaust from the space shuttle's final launch Stevens, Michael; Lossow, Stefan; Fiedler, Jens; Baumgarten, Gerd; übken, Franz-Josef; Hallgren, Kristofer; Hartogh, Paul; Randall, Cora; Lumpe, Jerry; Bailey, Scott; Niciejewski, R.; Meier, R.; Plane, John; Kochenash, Andrew; Murtagh, Donal; Englert, Christoph; Published by: Journal of Geophysical Research: Atmospheres Published on: Apr-10-2013 YEAR: 2012 DOI: 10.1029/2012JD017638 |
|
Modeling the effect of sudden stratospheric warming within the thermosphere--ionosphere system This paper presents an investigation of thermospheric and ionospheric response to the sudden stratospheric warming (SSW) event, which took place in January 2009. This period was characterized by low solar and geomagnetic activity. Analysis was carried out within the Global Self-consistent Model of Thermosphere, Ionosphere and Protonosphere (GSM TIP). The experimental data of the atmospheric temperatures obtained by Aura satellite above Irkutsk and ionosonde data over Yakutsk and Irkutsk were utilized as well. SSW event was modeled by specifying the temperature and density perturbations at the lower boundary of the GSM TIP model (80\ km altitude). It was shown that by setting disturbances in the form of a stationary planetary perturbation s=1 at the lower boundary of the thermosphere, one could reproduce the negative electron density disturbances in the F region of ionosphere during SSW events. Our scenario for the 2009 SSW event in the GSM TIP allowed to obtain results which are in a qualitative agreement with the observation data. Bessarab, F.S.; Korenkov, Yu.N.; Klimenko, M.V.; Klimenko, V.V.; Karpov, I.V.; Ratovsky, K.G.; Chernigovskaya, M.A.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 12/2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.09.005 Ionosphere; Modeling; sudden stratospheric warming; thermosphere |
|
Ionospheric plasma caves under the equatorial ionization anomaly This paper reports the existence of plasma caves, minima in the electron density located at 5\textendash10\textdegree to the magnetic equator, in the bottomside ionosphere based on electron densities simulations from the International Reference Ionosphere (IRI-2007) and clear evidences given by plasma density and drift measurements of the Dynamic Explorer 2 (DE 2) satellite during 1981\textendash1983. The IRI simulations suggest plasma caves as daytime features (08:00\textendash19:00 LT; length of 18,158 km in the longitudinal direction), that range from theE region up to about 300 km altitude with 10\textdegree (or 1100 km) width in the latitudinal direction. In situ measurements of the ion and electron densities probed by the DE 2 confirm the existence of the plasma caves at low altitudes of the EIA ionosphere. The unexpected downward and upward (or weakly and strongly upward) ion drifts at the magnetic equator and the two off equators seem to play an important role responsible for the plasma cave formation. Lee, I.; Liu, J; Lin, C.; Oyama, K.-I.; Chen, C; Chen, C.; Published by: Journal of Geophysical Research Published on: 11/2012 YEAR: 2012 DOI: 10.1029/2012JA017868 Dynamic Explorer 2; Equatorial ionization anomaly; plasma cave |
|
Ionospheric plasma caves under the equatorial ionization anomaly This paper reports the existence of plasma caves, minima in the electron density located at 5\textendash10\textdegree to the magnetic equator, in the bottomside ionosphere based on electron densities simulations from the International Reference Ionosphere (IRI-2007) and clear evidences given by plasma density and drift measurements of the Dynamic Explorer 2 (DE 2) satellite during 1981\textendash1983. The IRI simulations suggest plasma caves as daytime features (08:00\textendash19:00 LT; length of 18,158 km in the longitudinal direction), that range from theE region up to about 300 km altitude with 10\textdegree (or 1100 km) width in the latitudinal direction. In situ measurements of the ion and electron densities probed by the DE 2 confirm the existence of the plasma caves at low altitudes of the EIA ionosphere. The unexpected downward and upward (or weakly and strongly upward) ion drifts at the magnetic equator and the two off equators seem to play an important role responsible for the plasma cave formation. Lee, I.; Liu, J; Lin, C.; Oyama, K.-I.; Chen, C; Chen, C.; Published by: Journal of Geophysical Research Published on: 11/2012 YEAR: 2012 DOI: 10.1029/2012JA017868 Dynamic Explorer 2; Equatorial ionization anomaly; plasma cave |
|
This paper presents our effort to assimilate FORMOSAT-3/COSMIC (F3/C) GPS Occultation Experiment (GOX) observations into the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) by means of ensemble Kalman filtering (EnKF). The F3/C electron density profiles (EDPs) uniformly distributed around the globe which provide an excellent opportunity to monitor the ionospheric electron density structure. The NCAR TIE-GCM simulates the Earth\textquoterights thermosphere and ionosphere by using self-consistent solutions for the coupled nonlinear equations of hydrodynamics, neutral and ion chemistry, and electrodynamics. The F3/C EDP are combined with the TIE-GCM simulations by EnKF algorithms implemented in the NCAR Data Assimilation Research Testbed (DART) open-source community facility to compute the expected value of electron density, which is \textquoteleftthe best\textquoteright estimate of the current ionospheric state. Assimilation analyses obtained with real F3/C electron density profiles are compared with independent ground-based observations as well as the F3/C profiles themselves. The comparison shows the improvement of the primary ionospheric parameters, such as NmF2 and hmF2. Nevertheless, some unrealistic signatures appearing in the results and high rejection rates of observations due to the applied outlier threshold and quality control are found in the assimilation experiments. This paper further discusses the limitations of the model and the impact of ensemble member creation approaches on the assimilation results, and proposes possible methods to avoid these problems for future work. Lee, I.; Matsuo, T.; Richmond, A.; Liu, J; Wang, W.; Lin, C.; Anderson, J.; Chen, M.; Published by: Journal of Geophysical Research Published on: 10/2012 YEAR: 2012 DOI: 10.1029/2012JA017700 data assimilation; ensemble Kalman filter; FORMOSAT-3/COSMIC; Ionosphere |
|
This paper presents a study of thermospheric and ionospheric response to the 2008 minor sudden stratospheric warming (SSW) event. This period was characterized by low solar and geomagnetic activity. The study was performed using the Global Self-consistent Model of Thermosphere, Ionosphere, and Protonosphere (GSM TIP). Model results were compared with ionosonde data from Irkutsk, Kaliningrad, Sao Jose dos Campos, and Jicamarca. The SSW event was modeled by specifying the temperature and density perturbations at the lower boundary of the GSM TIP (80 km altitude). GSM TIP simulation allowed the reproduction of the lower thermosphere temperature disturbances (the occurrence of the quasi-wave 1 structure at 80\textendash130 km altitude with a vertical scale of \~40 km), the negative response of F2 region electron density and the positive response of electron temperature at 300 km during the 2008 minor SSW event. The main formation mechanism of the global ionospheric response is due to the disturbances (decrease) in then(O)/n(N2) ratio. The change in zonal electric field is another important mechanism of the ionospheric response at low latitudes. Korenkov, Y.; Klimenko, V.; Klimenko, M.; Bessarab, F.; Korenkova, N.; Ratovsky, K.; Chernigovskaya, M.; Shcherbakov, A.; Sahai, Y.; Fagundes, P.; de Jesus, R.; de Abreu, A.; Condor, P.; Published by: Journal of Geophysical Research Published on: 10/2012 YEAR: 2012 DOI: 10.1029/2012JA018018 Electric field; Ionosphere; sudden stratospheric warming; thermosphere |
|
This paper presents a study of thermospheric and ionospheric response to the 2008 minor sudden stratospheric warming (SSW) event. This period was characterized by low solar and geomagnetic activity. The study was performed using the Global Self-consistent Model of Thermosphere, Ionosphere, and Protonosphere (GSM TIP). Model results were compared with ionosonde data from Irkutsk, Kaliningrad, Sao Jose dos Campos, and Jicamarca. The SSW event was modeled by specifying the temperature and density perturbations at the lower boundary of the GSM TIP (80 km altitude). GSM TIP simulation allowed the reproduction of the lower thermosphere temperature disturbances (the occurrence of the quasi-wave 1 structure at 80\textendash130 km altitude with a vertical scale of \~40 km), the negative response of F2 region electron density and the positive response of electron temperature at 300 km during the 2008 minor SSW event. The main formation mechanism of the global ionospheric response is due to the disturbances (decrease) in then(O)/n(N2) ratio. The change in zonal electric field is another important mechanism of the ionospheric response at low latitudes. Korenkov, Y.; Klimenko, V.; Klimenko, M.; Bessarab, F.; Korenkova, N.; Ratovsky, K.; Chernigovskaya, M.; Shcherbakov, A.; Sahai, Y.; Fagundes, P.; de Jesus, R.; de Abreu, A.; Condor, P.; Published by: Journal of Geophysical Research Published on: 10/2012 YEAR: 2012 DOI: 10.1029/2012JA018018 Electric field; Ionosphere; sudden stratospheric warming; thermosphere |
|
This study, for the first time, presented the long-term variations of Midlatitude Summer Nighttime Anomaly (MSNA) in the two hemispheres by using 66 ground-based ionosonde observations from 1957 to 2010. MSNA is characterized by the feature of higher nighttime electron density than daytime density in the midlatitude region during local summer months. Observations from 66 ionosonde stations were used to calculate the MSNA index which is defined by the difference between nighttime and noontime NmF2 values. The MSNA occurrence is determined by positive value of the MSNA index. The global distribution map of the MSNA index shows that there are three regions of intense MSNA. Three ionosonde stations in each of active MSNA regions were chosen to study the long-term variation of MSNA covering longer than one solar cycle. One station in the southern hemisphere is AIJ6N (Argentine IS; 65.2\textdegreeS, 64.3\textdegreeW geographic) and two stations in the northern hemisphere are LN047 (Lannion; 48.8\textdegreeN, -3.4\textdegreeE geographic) and MG560 (Magadan; 60.0\textdegreeN, 151.0\textdegreeE geographic). Results show that there is a clear solar activity negative dependence of the MSNA index, high MSNA in the low solar activity condition and low MSNA in the high solar activity condition. The seasonal and solar activity variations of the MSNA index are explained by the combined effects of the vertical plasma drift induced by the neutral wind and photoionization during the nighttime. Chen, C.; Saito, A.; Lin, C.; Liu, J; Published by: Journal of Geophysical Research Published on: 07/2012 YEAR: 2012 DOI: 10.1029/2011JA017138 ionization-uplift effect; midlatitude summer nighttime anomaly; MSNA index |
|
This paper provides an overview on the recent progress in studying the ionospheric response to atmospheric tides forced from below. The global spatial structure and temporal variability of the atmospheric temperature tides and their ionospheric responses are considered on the basis of modern satellite-board data (COSMIC and TIMED). The tidal waves from the two data sets have been extracted by one and the same data analysis method. The similarity between the lower thermospheric temperature tides and their ionospheric responses provides evidence for confirming the new paradigm of atmosphere-ionosphere coupling. This paper provides also new experimental results which give an explanation why the WN4 and partly WN3 longitude structures are so prominent pattern in the ionosphere. These results present evidence indicating that the WN4 (WN3) structure is not generated only by the DE3 (DE2) tide as it has been often assumed. The DE3 (DE2) tide remains the leading contributor, but the SPW4 and SE2 (SPW3, DW4 and SE1) waves have their effects as well in a way that the ionospheric response becomes almost double (1.5 time stronger). The paper presents also the global distribution and temporal variability of the sun-synchronous 24-h (DW1), 12-h (SW2) and 8-h (TW3) electron density oscillations. It has been shown that while the latitude and altitude structure of the ionospheric SW2 response is predominantly shaped by the migrating SW2 tide forced from below the DW1 response is mainly due to daily variability of the photo-ionization. The peculiar vertical structure of the ionospheric TW3 response, that shows downward/upward phase progression, calls for further study of the physical processes shaping this ionospheric response. Pancheva, Dora; Mukhtarov, Plamen; Published by: Space Science Reviews Published on: 06/2012 YEAR: 2012 DOI: 10.1007/s11214-011-9837-1 Fountain effect; Ionospheric response; Modulated vertical plasma drift; Nonmigrating tides |
|
The global ionospheric response to a stratospheric sudden warming (SSW) is studied using three-dimensional electron density maps derived from radio occultation observations of FORMOSAT-3/COSMIC during the 2009 SSW periods. Results show that the ionospheric electron density at EIA crests exhibit a morning/early afternoon increase followed by an afternoon decrease and an evening increase, indicative of a semidiurnal component during the SSW period, which is consistent with recent studies. The latitude-altitude electron density slice maps show that the SSW related modifications of the equatorial plasma fountain interact with the existing summer-to-winter neutral winds and resulting in a north\textendashsouth asymmetry. The global ionospheric response shows a clear longitudinal dependence in the equatorial plasma fountain enhancement during morning/early afternoon, inferred from the duration of the equatorial ionization anomaly (EIA) enhancement. Following the enhancement, prominent global EIA reductions resulting from the equatorial plasma fountain weakening in the afternoon sector are seen. The ionospheric response to the 2009 SSW event is also compared with the usual seasonal variation during January\textendashFebruary 2007. Instead of showing the electron density increase in the northern hemisphere and decrease in the southern hemisphere as the usual seasonal variation does, the SSW period ionosphere shows prominent global electron density reductions in the afternoon period during the 2009 SSW event. Lin, C.; Lin, J.; Chang, L.; Liu, J; Chen, C.; Chen, W.; Huang, H.; Liu, C.; Published by: Journal of Geophysical Research Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2011JA017230 FORMOSAT-3/COSMIC; ionospheric responses to stratospheric sudden warming |
|
The global ionospheric response to a stratospheric sudden warming (SSW) is studied using three-dimensional electron density maps derived from radio occultation observations of FORMOSAT-3/COSMIC during the 2009 SSW periods. Results show that the ionospheric electron density at EIA crests exhibit a morning/early afternoon increase followed by an afternoon decrease and an evening increase, indicative of a semidiurnal component during the SSW period, which is consistent with recent studies. The latitude-altitude electron density slice maps show that the SSW related modifications of the equatorial plasma fountain interact with the existing summer-to-winter neutral winds and resulting in a north\textendashsouth asymmetry. The global ionospheric response shows a clear longitudinal dependence in the equatorial plasma fountain enhancement during morning/early afternoon, inferred from the duration of the equatorial ionization anomaly (EIA) enhancement. Following the enhancement, prominent global EIA reductions resulting from the equatorial plasma fountain weakening in the afternoon sector are seen. The ionospheric response to the 2009 SSW event is also compared with the usual seasonal variation during January\textendashFebruary 2007. Instead of showing the electron density increase in the northern hemisphere and decrease in the southern hemisphere as the usual seasonal variation does, the SSW period ionosphere shows prominent global electron density reductions in the afternoon period during the 2009 SSW event. Lin, C.; Lin, J.; Chang, L.; Liu, J; Chen, C.; Chen, W.; Huang, H.; Liu, C.; Published by: Journal of Geophysical Research Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2011JA017230 FORMOSAT-3/COSMIC; ionospheric responses to stratospheric sudden warming |
|
The Wind Imaging Interferometer (WINDII) was launched on the NASA\textquoterights Upper Atmosphere Research Satellite on 12 September 1991 and operated until 2003. Its role in the mission was to measure vector winds in the Earth\textquoterights atmosphere from 80 to 110 km, but its measurements extended to nearly 300 km. The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(1S) and O(1D) lines, as well as lines in the OH Meinel (8,3) and O2 Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements. The dominant wind field, the first one observed by WINDII, was that of the migrating diurnal tide at the equator. The overall most notable WINDII contribution followed from this: determining the influence of dynamics on the transport of atmospheric species. Currently, nonmigrating tides are being studied in the thermosphere at both equatorial and high latitudes. Other aspects investigated included solar and geomagnetic influences, temperatures from atmospheric-scale heights, nitric oxide concentrations, and the occurrence of polar mesospheric clouds. The results of these observations are reviewed from a perspective of 20 years. A future perspective is then projected, involving more recently developed concepts. It is intended that this description will be helpful for those planning future missions. Shepherd, G.; Thuillier, G.; Cho, Y.-M.; Duboin, M.-L.; Evans, W.; Gault, W.; Hersom, C.; Kendall, D.; Lathuillère, C.; Lowe, R.; McDade, I.; Rochon, Y.; Shepherd, M.; Solheim, B.; Wang, D.-Y.; Ward, W.; Published by: Reviews of Geophysics Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2012RG000390 airglow; dynamics; interferometers; mesosphere; temperature; winds |
|
The Wind Imaging Interferometer (WINDII) was launched on the NASA\textquoterights Upper Atmosphere Research Satellite on 12 September 1991 and operated until 2003. Its role in the mission was to measure vector winds in the Earth\textquoterights atmosphere from 80 to 110 km, but its measurements extended to nearly 300 km. The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(1S) and O(1D) lines, as well as lines in the OH Meinel (8,3) and O2 Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements. The dominant wind field, the first one observed by WINDII, was that of the migrating diurnal tide at the equator. The overall most notable WINDII contribution followed from this: determining the influence of dynamics on the transport of atmospheric species. Currently, nonmigrating tides are being studied in the thermosphere at both equatorial and high latitudes. Other aspects investigated included solar and geomagnetic influences, temperatures from atmospheric-scale heights, nitric oxide concentrations, and the occurrence of polar mesospheric clouds. The results of these observations are reviewed from a perspective of 20 years. A future perspective is then projected, involving more recently developed concepts. It is intended that this description will be helpful for those planning future missions. Shepherd, G.; Thuillier, G.; Cho, Y.-M.; Duboin, M.-L.; Evans, W.; Gault, W.; Hersom, C.; Kendall, D.; Lathuillère, C.; Lowe, R.; McDade, I.; Rochon, Y.; Shepherd, M.; Solheim, B.; Wang, D.-Y.; Ward, W.; Published by: Reviews of Geophysics Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2012RG000390 airglow; dynamics; interferometers; mesosphere; temperature; winds |
|
The Wind Imaging Interferometer (WINDII) was launched on the NASA\textquoterights Upper Atmosphere Research Satellite on 12 September 1991 and operated until 2003. Its role in the mission was to measure vector winds in the Earth\textquoterights atmosphere from 80 to 110 km, but its measurements extended to nearly 300 km. The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(1S) and O(1D) lines, as well as lines in the OH Meinel (8,3) and O2 Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements. The dominant wind field, the first one observed by WINDII, was that of the migrating diurnal tide at the equator. The overall most notable WINDII contribution followed from this: determining the influence of dynamics on the transport of atmospheric species. Currently, nonmigrating tides are being studied in the thermosphere at both equatorial and high latitudes. Other aspects investigated included solar and geomagnetic influences, temperatures from atmospheric-scale heights, nitric oxide concentrations, and the occurrence of polar mesospheric clouds. The results of these observations are reviewed from a perspective of 20 years. A future perspective is then projected, involving more recently developed concepts. It is intended that this description will be helpful for those planning future missions. Shepherd, G.; Thuillier, G.; Cho, Y.-M.; Duboin, M.-L.; Evans, W.; Gault, W.; Hersom, C.; Kendall, D.; Lathuillère, C.; Lowe, R.; McDade, I.; Rochon, Y.; Shepherd, M.; Solheim, B.; Wang, D.-Y.; Ward, W.; Published by: Reviews of Geophysics Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2012RG000390 airglow; dynamics; interferometers; mesosphere; temperature; winds |
|
The Wind Imaging Interferometer (WINDII) was launched on the NASA\textquoterights Upper Atmosphere Research Satellite on 12 September 1991 and operated until 2003. Its role in the mission was to measure vector winds in the Earth\textquoterights atmosphere from 80 to 110 km, but its measurements extended to nearly 300 km. The approach employed was to measure Doppler shifts from a suite of visible region airglow lines emitted over this altitude range. These included atomic oxygen O(1S) and O(1D) lines, as well as lines in the OH Meinel (8,3) and O2 Atmospheric (0,0) bands. The instrument employed was a Doppler Michelson Interferometer that measured the Doppler shift as a phase shift of the cosinusoidal interferogram generated by single airglow lines. An extensive validation program was conducted after launch to confirm the accuracy of the measurements. The dominant wind field, the first one observed by WINDII, was that of the migrating diurnal tide at the equator. The overall most notable WINDII contribution followed from this: determining the influence of dynamics on the transport of atmospheric species. Currently, nonmigrating tides are being studied in the thermosphere at both equatorial and high latitudes. Other aspects investigated included solar and geomagnetic influences, temperatures from atmospheric-scale heights, nitric oxide concentrations, and the occurrence of polar mesospheric clouds. The results of these observations are reviewed from a perspective of 20 years. A future perspective is then projected, involving more recently developed concepts. It is intended that this description will be helpful for those planning future missions. Shepherd, G.; Thuillier, G.; Cho, Y.-M.; Duboin, M.-L.; Evans, W.; Gault, W.; Hersom, C.; Kendall, D.; Lathuillère, C.; Lowe, R.; McDade, I.; Rochon, Y.; Shepherd, M.; Solheim, B.; Wang, D.-Y.; Ward, W.; Published by: Reviews of Geophysics Published on: 06/2012 YEAR: 2012 DOI: 10.1029/2012RG000390 airglow; dynamics; interferometers; mesosphere; temperature; winds |
|
Equatorial ionospheric responses during two magnetic storms of moderate intensity are investigated, for the first time, by conjugate point observations in Brazil. The study focuses on storm-induced changes in the evening prereversal vertical drift, thermospheric trans-equatorial winds, spread F/plasma bubble irregularity development, electron density/plasma frequency heights, the EIA strength, and zonal plasma drifts. It is based on data obtained from five Digisondes operated in Brazil, three of them being part of a conjugate point equatorial experiment (COPEX) involving a dip equatorial and two magnetic conjugate sites at \textpm12\textdegree. The other two were operated at the equatorial ionization anomaly (EIA) trough and crest locations at nearby magnetic meridians. The results bring out, and clarify, many outstanding aspects of the strong influence of storm time electric fields on the equatorial ionosphere at different phases of the two long lasting storm sequences. During both storms prompt penetration electric fields dominated the ionospheric response features as compared to the disturbance wind dynamo effects that were not very conspicuous. An under-shielding (over-shielding) electric field occurring in the evening hours causes enhancement (suppression) of the prereversal vertical drift and post sunset spread F/plasma bubble generation. The same electric fields cause post sunset EIA enhancement and suppression, respectively. Post sunset (post midnight) spread F can develop from under-shielding (over-shielding) electric fields, while it can be disrupted by over-shielding (under-shielding) electric field. Trans-equatorial winds are found to be ineffective to stabilize the post sunset F region against the destabilizing effect of strong prereversal vertical drift. Storm time westward plasma drifts are found to be driven by prompt penetration eastward electric fields (through their effect of inducing vertical Hall electric fields), rather than by a disturbance westward thermospheric wind during these storms. Abdu, M.; Batista, I.; Bertoni, F.; Reinisch, B.; Kherani, E.; Sobral, J.; Published by: Journal of Geophysical Research Published on: 05/2012 YEAR: 2012 DOI: 10.1029/2011JA017174 Equatorial ionosphere; Magnetic storms; plasma bubbles; plasma drifts; spread F; transequatorial winds |
|
Research on Retrieving Thermospheric O/N2 from FUV Remote Sensing Magnetic storms usually cause significant departures of thermospheric O and N2\ from their normal values. To study the effects on thermospheric neutral species caused by magnetic storms, a method to retrieve thermospheric O/N2\ based on the data obtained from global ultraviolet imager on board TIMED is presented. With the help of AURIC, the normalizations of observing angles and SZAs were preformed to the measurements and a relationship between 135.6/LBHs and O/N2\ was established. Finally, applying the proposed method to retrieve O/N2\ during a magnetic period(29, September\textemdash4, October, 2002), it was shown that magnetic storms could induce significant O/N2\ depletion, extending from the polar regions towards the equator. Peng, S.; Tang, Y.; Wang, J.; Zheng, X.; Published by: Spectroscopy and Spectral Analysis Published on: 05/2012 YEAR: 2012 DOI: 10.3964/j.issn.1000-0593(2012)05-1296-05 |
|
Optical observations of large-scale undulations in the 23rd cycle of solar activity A statistical analysis of observations of large-scale undulations during the 23rd cycle of solar activity was performed using optical data from two stations: Tixie (71.6\textdegreeN, 128.9\textdegreeE) and Zhigansk (66.8\textdegreeN, 123.4\textdegreeE). The total number of events recorded was 54 (43 events at Tixie and 11 at Zhigansk). The complete list of observed events is presented. The occurrence frequency of eveningside (17\textendash23 LT) undulations during the solar activity growth (1999) and decline (2003\textendash2005) phases tends to increase. Large-scale undulations were shown to be generated both on the equatorward boundary of the diffuse auroral zone and inside the diffuse zone, which does not necessarily occur during magnetic storms. Baishev, D.; Barkova, E.; Yumoto, K.; Published by: Geomagnetism and Aeronomy Published on: 04/2012 YEAR: 2012 DOI: 10.1134/S0016793212020028 |
|
Knight, HK; Strickland, DJ; Correira, J; Hecht, JH; Straus, PR; Published by: Journal of Geophysical Research: Space Physics Published on: |
|
Schunk, Robert; Scherliess, L; Eccles, JV; Gardner, LC; Sojka, JJ; Zhu, L; Pi, X; Mannucci, A; Wilson, BD; Komjathy, A; , others; Published by: Published on: |
|
Optical System Design of a Spaceborne Broadband Far Ultraviolet Hyperspectral Imager According to the application requirements for remote sensing of upper atmosphere,a reflective optical system of spaceborne far ultraviolet hyperspectral imager is designed.Which is composed of a scan mirror,an off-axis parabolic telescope and a toroidal grating spectrometer.An aberration-correction method for concave toroidal grating is developed.The initial parameters are solved based on the geometrical aberration theory of concave grating and then optimized using the optical design software Zemax,and the toroidal gating spectrometer is designed.The root mean square of spot radius is less than 16 μm in the working waveband.Aberration is corrected simultaneously in broadband and the requirement of spectral resolution of 0.6 nm is satisfied,which indicates the aberration-correction method is feasible.Ray tracing and analysing are performed by Zemax software.Analyzed results demonstrate that the modulation transfer function for different wavelength is more than 0.8,which satisfies the design requirements.The construction is compact and suitable for application in space remote sensing. Published by: Acta Optica Sinica Published on: optical design hyperspectral imager toroidal grating far ultraviolet geometrical aberration |
| 2011 |
|
Strong evidence for couplings between the ionospheric wave-4 structure and atmospheric tides He, Maosheng; Liu, Libo; Wan, Weixing; Wei, Yong; Published by: Geophysical Research Letters Published on: Jan-07-2011 YEAR: 2011 DOI: 10.1029/2011GL047855 |
|
Global distributions of OH and O2 (1.27 μm) nightglow emissions observed by TIMED satellite Gao, Hong; Xu, JiYao; Chen, GuangMing; Yuan, Wei; Beletsky, A.; Published by: Science China Technological Sciences Published on: Jan-02-2011 YEAR: 2011 DOI: 10.1007/s11431-010-4236-5 |
|
The O I 135.6 nm airglow observations of the midlatitude summer nighttime anomaly by TIMED/GUVI Hsu, M.; Lin, C.; Hsu, R.; Liu, J; Paxton, L.; Su, H.; Tsai, H.; Rajesh, P.; Chen, C.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011 DOI: 10.1029/2010JA016150 |