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Found 37 entries in the Bibliography.
Showing entries from 1 through 37
| 2022 |
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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 |
| 2020 |
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The onset of substorms is associated with bursty enhancements of Alfv\ en wave power throughout the magnetotail. While impossible to assess the total Alfv\ en wave power in the entire magnetotail, we have instead monitored waves that are funneled into the auroral acceleration region, in order to assess the temporal evolution of Alfv\ en wave power above the nightside auroral zone in relation to substorm phases. The substorms were grouped by three conditions: nonstorm periods, storm periods, and all (unconditioned) periods. Using superposed epoch analysis, we found that the global magnetohydrodynamic Alfv\ en wave power increased significantly at onset for all three conditions, while a power decrease to pre-onset values occurred within 2 h. Specifically, the peak inflowing power during the expansion phase was 5.7 GW for unconditioned substorms, 5.6 GW for nonstorm-time substorms, and 7.8 GW for storm-time substorms. These results correspond to power increases with respect to pre-onset values of 138\%, 366\%, and 200\%, respectively. Additional analysis in relation to the aurora was performed for nonstorm-time substorms only. During the expansion phase, about 50\% of the Alfv\ en wave power over the entire nightside auroral zone is collocated with the auroral bulge region. Furthermore, the total inflowing Alfv\ en wave power over the entire nightside auroral zone is 17\% of the conjugate auroral power, while the inflowing power over the auroral bulge region is 32\% of the conjugate aurora. However, allowing for a finite absorption efficiency inside the auroral acceleration region, the likely average Alfv\ enic contributions to the aurora are approximately 10\% and 18\%,respectively. Keiling, Andreas; Thaller, Scott; Dombeck, John; Wygant, John; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2020 YEAR: 2020 DOI: 10.1029/2019JA027444 Alfven wave; Alfvenic electron; AURORA; auroral acceleration; magnetotail; Substorm |
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Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Oberheide, J; Pedatella, NM; Gan, Q; Kumari, K; Burns, AG; Eastes, RW; Published by: Geophysical Research Letters Published on: |
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Nishimura, Y; Yang, J; Weygand, JM; Wang, W; Kosar, B; Donovan, EF; , Angelopoulos; Paxton, LJ; Nishitani, N; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Particle precipitation is a central aspect of space weather, as it strongly couples the magnetosphere and the ionosphere and can be responsible for radio signal disruption at high Grandin, Maxime; Turc, Lucile; Battarbee, Markus; Ganse, Urs; Johlander, Andreas; Pfau-Kempf, Yann; Dubart, Maxime; Palmroth, Minna; Published by: Journal of space weather and space climate Published on: YEAR: 2020 DOI: 10.1051/swsc/2020053 |
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This paper focuses on unique aspects of the ionospheric response at conjugate locations over Europe and South Africa during the 7–8 September 2017 geomagnetic storm including Habarulema, John; Katamzi-Joseph, Zama; a, Dalia; Nndanganeni, Rendani; Matamba, Tshimangadzo; Tshisaphungo, Mpho; Buchert, Stephan; Kosch, Michael; Lotz, Stefan; Cilliers, Pierre; , others; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2020 DOI: 10.1029/2020JA028307 |
| 2019 |
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As part of its International Capabilities Assessment effort, the Community Coordinated Modeling Center initiated several working teams, one of which is focused on the validation of models and methods for determining auroral electrodynamic parameters, including particle precipitation, conductivities, electric fields, neutral density and winds, currents, Joule heating, auroral boundaries, and ion outflow. Auroral electrodynamic properties are needed as input to space weather models, to test and validate the accuracy of physical models, and to provide needed information for space weather customers and researchers. The working team developed a process for validating auroral electrodynamic quantities that begins with the selection of a set of events, followed by construction of ground truth databases using all available data and assimilative data analysis techniques. Using optimized, predefined metrics, the ground truth data for selected events can be used to assess model performance and improvement over time. The availability of global observations and sophisticated data assimilation techniques provides the means to create accurate ground truth databases routinely and accurately. Robinson, Robert; Zhang, Yongliang; Garcia-Sage, Katherine; Fang, Xiaohua; Verkhoglyadova, Olga; Ngwira, Chigomezyo; Bingham, Suzy; Kosar, Burcu; Zheng, Yihua; Kaeppler, Stephen; Liemohn, Michael; Weygand, James; Crowley, Geoffrey; Merkin, Viacheslav; McGranaghan, Ryan; Mannucci, Anthony; Published by: Space Weather Published on: 01/2019 YEAR: 2019 DOI: 10.1029/2018SW002127 |
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Research Progress on On-Orbit Calibration Technology for Far Ultraviolet Payload Li-ping, Fu; Nan, Jia; Xiu-qing, Hu; Tian, Mao; Fang, Jiang; Yun-gang, Wang; Ru-yi, Peng; Tian-fang, Wang; Da-xin, Wang; Shuang-tuan, Dou; , others; Published by: Published on: |
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Particle precipitation plays a key role in the coupling of the terrestrial magnetosphere and ionosphere by modifying the upper atmospheric conductivity and chemistry, driving field-aligned currents, and producing aurora. Yet quantitative observations of precipitating fluxes are limited, since ground-based instruments can only provide indirect measurements of precipitation, while particle telescopes aboard spacecraft merely enable point-like in situ observations with an inherently coarse time resolution above a given location. Further, orbit timescales generally prevent the analysis of whole events. On the other hand, global magnetospheric simulations can provide estimations of particle precipitation with a global view and higher time resolution. We present the first results of auroral (∼1–30 keV) proton precipitation estimation using the Vlasiator global hybrid-Vlasov model in a noon–midnight meridional plane simulation driven by steady solar wind with a southward interplanetary magnetic field. We first calculate the bounce loss-cone angle value at selected locations in the simulated nightside magnetosphere. Then, using the velocity distribution function representation of the proton population at those selected points, we study the population inside the loss cone. This enables the estimation of differential precipitating number fluxes as would be measured by a particle detector aboard a low-Earth-orbiting (LEO) spacecraft. The obtained differential flux values are in agreement with a well-established empirical model in the midnight sector, as are the integral energy flux and mean precipitating energy. We discuss the time evolution of the precipitation parameters derived in this manner in the global context of nightside magnetospheric activity in this simulation, and we find in particular that precipitation bursts of <1 min duration can be self-consistently and unambiguously associated with dipolarising flux bundles generated by tail reconnection. We also find that the transition region seems to partly regulate the transmission of precipitating protons to the inner magnetosphere, suggesting that it has an active role in regulating ionospheric precipitation. Grandin, Maxime; Battarbee, Markus; Osmane, Adnane; Ganse, Urs; Pfau-Kempf, Yann; Turc, Lucile; Brito, Thiago; Koskela, Tuomas; Dubart, Maxime; Palmroth, Minna; Published by: Published on: YEAR: 2019 DOI: 10.5194/angeo-37-791-2019 |
| 2017 |
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Oberheide, Jens; Krier, Christopher; Gan, Quan; Nischal, Nirmal; Zhang, Yongliang; Chang, Loren; Published by: Published on: |
| 2015 |
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We report, for the first time, an auroral undulation event on 1 May 2013 observed by an all-sky imager (ASI) at Athabasca (L = 4.6), Canada, for which in situ field and particle measurements in the conjugate magnetosphere were available from a Van Allen Probes spacecraft. The ASI observed a train of auroral undulation structures emerging spontaneously in the pre-midnight subauroral ionosphere, during the growth phase of a substorm. The undulations had an azimuthal wavelength of ~180 km and propagated westward at a speed of 3\textendash4 km s-1. The successive passage over an observing point yielded quasi-periodic oscillations in diffuse auroral emissions with a period of ~40 s. The azimuthal wave number m of the auroral luminosity oscillations was found to be m ~ -103. During the event the spacecraft \textendash being on tailward stretched field lines ~0.5 RE outside the plasmapause that mapped into the ionosphere conjugate to the auroral undulations \textendash encountered intense poloidal ULF oscillations in the magnetic and electric fields. We identify the field oscillations to be the second harmonic mode along the magnetic field line through comparisons of the observed wave properties with theoretical predictions. The field oscillations were accompanied by oscillations in proton and electron fluxes. Most interestingly, both field and particle oscillations at the spacecraft had one-to-one association with the auroral luminosity oscillations around its footprint. Our findings strongly suggest that this auroral undulation event is closely linked to the generation of second harmonic poloidal waves Motoba, T.; Takahashi, K.; Ukhorskiy, A.; Gkioulidou, M.; Mitchell, D.; Lanzerotti, L.; Korotova, G.; Donovan, E.; Wygant, J.; Kletzing, C.; Kurth, W.; Blake, J.; Published by: Journal of Geophysical Research: Space Physics Published on: 02/2015 YEAR: 2015 DOI: 10.1002/2014JA020863 |
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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 |
| 2014 |
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Limb Viewing Hyper Spectral Imager (LiVHySI) for airglow measurements onboard YOUTHSAT-1 Bisht, R.S.; Hait, A.K.; Babu, P.N.; Sarkar, S.S.; Benerji, A.; Biswas, A.; Saji, A.K.; Samudraiah, D.R.M.; Kirankumar, A.S.; Pant, T.K.; Parimalarangan, T.; Published by: Advances in Space Research Published on: 08/2014 YEAR: 2014 DOI: 10.1016/j.asr.2014.01.016 airglow; Electron density; Ionosphere; Rayleigh; thermosphere; Volume emission |
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Gravity wave activity and dissipation in the height range from the low stratosphere to the low thermosphere (25\textendash115 km) covering latitudes between 50\textdegreeS and 50\textdegreeN are statistically studied by using 9-year (January 22, 2002\textendashDecember 31, 2010) SABER/TIMED temperature data. We propose a method to extract realistic gravity wave fluctuations from the temperature profiles and treat square temperature fluctuations as GW activity. Overall, the gravity wave activity generally increases with height. Near the equator (0\textdegree\textendash10\textdegree), the gravity wave activity shows a quasi-biennial variation in the stratosphere (below 40 km) while from 20\textdegree to 30\textdegree, it exhibits an annual variation below 40 km; in low latitudes (0\textdegree\textendash30\textdegree) between the upper stratosphere and the low thermosphere (40\textendash115 km), the gravity wave activity shows a semi-annual variation. In middle latitudes (40\textdegree\textendash50\textdegree), the gravity wave activity has a clear annual variation below 85 km. In addition, we observe a four-monthly variation with peaks occurring usually in April, August, December in the northern hemisphere and in February, June, October in the southern hemisphere, respectively, above 85 km in middle latitudes, which has been seldom reported in gravity wave activity. In order to study the dissipation of gravity wave propagation, we calculate the gravity wave dissipation ratio, which is defined as the ratio of the gravity wave growth scale height to the atmosphere density scale height. The height variation of the dissipation ratio indicates that strong gravity wave dissipation mainly concentrates in the three height regions: the stratosphere (30\textendash60 km), the mesopause (around 85 km) and the low thermosphere (above 100 km). Besides, gravity wave energy enhancement can be also observed in the background atmosphere. Shuai, Jing; Zhang, ShaoDong; Huang, ChunMing; YI, Fan; Huang, KaiMing; Gan, Quan; Gong, Yun; Published by: Science China Technological Sciences Published on: 05/2014 YEAR: 2014 DOI: 10.1007/s11431-014-5527-z climatology; dissipation; gravity wave; middle and high atmosphere; SABER; TIMED |
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Mars Reconnaissance Orbiter observation of Comet C/2013 A1 (Siding Spring) Tamppari, Leslie; Zurek, Richard; Cantor, Bruce; Delamere, WA; Egan, Anthony; Humm, David; Kass, David; McEwen, Alfred; McGovern, Andy; Phillips, Roger; , others; Published by: Published on: |
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The Role of Thermospheric Composition in Ionospheric Forecasting Chartier, A; Morgan, F; Bust, GS; Mitchell, CN; Published by: Published on: |
| 2013 |
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Tobiska, W; Knipp, DJ; Burke, WJ; Bouwer, D; Bailey, JJ; Hagan, MP; Didkovsky, LV; Garrett, HB; Bowman, BR; Gannon, JL; , others; Published by: Published on: |
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Tobiska, W; Knipp, DJ; Burke, WJ; Bouwer, D; Bailey, JJ; Hagan, MP; Didkovsky, LV; Garrett, HB; Bowman, BR; Gannon, JL; , others; Published by: Published on: |
| 2012 |
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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 |
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The O2 (b1$\Sigma$) dayglow emissions: Application to middle and upper atmosphere remote sensing Yee, Jeng-Hwa; DeMajistre, R; Morgan, F; Published by: Canadian Journal of Physics Published on: |
| 2010 |
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Nishimura, Y.; Kikuchi, T.; Shinbori, A.; Wygant, J.; Tsuji, Y.; Hori, T.; Ono, T.; Fujita, S.; Tanaka, T.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2010JA015491 |
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England, S.; Immel, T.; Huba, J.; Hagan, M.; Maute, A.; DeMajistre, R.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JA014894 |
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Hecht, JH; Mulligan, T; Clemmons, JH; Strickland, DJ; Correira, J; Conde, MG; Published by: Published on: |
| 2008 |
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Hecht, JH; Mulligan, T; Strickland, DJ; Kochenash, AJ; Murayama, Y; Tanaka, Y-M; Evans, DS; Conde, MG; Donovan, EF; Rich, FJ; , others; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2007 |
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A climatology of nonmigrating semidiurnal tides from TIMED Doppler Interferometer (TIDI) wind data Oberheide, J.; Wu, Q.; Killeen, T.L.; Hagan, M.E.; Roble, R.G.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-12-2007 YEAR: 2007 DOI: 10.1016/j.jastp.2007.05.010 |
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Lin, C.; Wang, W.; Hagan, M.; Hsiao, C.; Immel, T.; Hsu, M.; Liu, J; Paxton, L.; Fang, T.; Liu, C.; Published by: Geophysical Research Letters Published on: Jan-01-2007 YEAR: 2007 DOI: 10.1029/2007GL029265 |
| 2006 |
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England, S.; Immel, T.; Sagawa, E.; Henderson, S.; Hagan, M.; Mende, S.; Frey, H.; Swenson, C.; Paxton, L.; Published by: Journal of Geophysical Research Published on: Jan-01-2006 YEAR: 2006 DOI: 10.1029/2006JA011795 |
| 2005 |
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Extended kalman filter for autonomous satellite navigation system Devereux, William; Chacos, Albert; Asher, Mark; Duven, Dennis; Kusterer, Thomas; Morgan, Richard; Published by: Published on: 2 |
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Some of the most intense solar flares measured in 0.1 to 0.8 nm x-rays in recent history occurred near the end of 2003. The Nov 4 event is the largest in the NOAA records (X28) and the Oct 28 flare was the fourth most intense (X17). The Oct 29 flare was class X7. These flares are compared and contrasted to the July 14, 2000 Bastille Day (X10) event using the SOHO SEM 26.0 to 34.0 nm EUV and TIMED SEE 0.1\textendash194 nm data. High time resolution, \~30s ground-base GPS data and the GUVI FUV dayglow data are used to examine the flare-ionosphere relationship. In the 26.0 to 34.0 nm wavelength range, the Oct 28 flare is found to have a peak intensity greater than twice that of the Nov 4 flare, indicating strong spectral variability from flare-to-flare. Solar absorption of the EUV portion of the Nov 4 limb event is a possible cause. The dayside ionosphere responds dramatically (\~2.5 min 1/e rise time) to the x-ray and EUV input by an abrupt increase in total electron content (TEC). The Oct 28 TEC ionospheric peak enhancement at the subsolar point is \~25 TECU (25 \texttimes 1012 electrons/cm2) or 30\% above background. In comparison, the Nov 4, Oct 29 and the Bastille Day events have \~5\textendash7 TECU peak enhancements above background. The Oct 28 TEC enhancement lasts \~3 hrs, far longer than the flare duration. This latter ionospheric feature is consistent with increased electron production in the middle altitude ionosphere, where recombination rates are low. It is the EUV portion of the flare spectrum that is responsible for photoionization of this region. Further modeling will be necessary to fully understand the detailed physics and chemistry of flare-ionosphere coupling. Tsurutani, B.; Judge, D.; Guarnieri, F.; Gangopadhyay, P.; Jones, A.; Nuttall, J.; Zambon, G.A.; Didkovsky, L.; Mannucci, A.J.; Iijima, B.; Meier, R.; Immel, T.J.; Woods, T.; Prasad, S.; Floyd, L.; Huba, J.; Solomon, S.; Straus, P.; Viereck, R.; Published by: Geophysical Research Letters Published on: 02/2005 YEAR: 2005 DOI: 10.1029/2004GL021475 |
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England, SL; Immel, TJ; Sagawa, E; Henderson, S; Hagan, ME; Mende, SB; Frey, HU; Swenson, C; Paxton, LJ; Published by: Published on: |
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Kozyra, JU; Crowley, G; Emery, BA; Fang, XH; Hagan, ME; Lu, G; Mlynczak, MG; Niciejewski, RJ; Palo, SE; Paxton, LJ; , others; Published by: Published on: |
| 2004 |
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First Three Years of TIMED: New Results in Sun-Earth Connections Kozyra, JU; Crowley, G; Goncharenko, LP; Hagan, ME; Lu, G; Mlynczak, MG; Paxton, LJ; RUSSELL, JM; Solomon, SC; Talaat, ER; , others; Published by: Published on: |
| 2003 |
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Autonomous satellite navigation system Devereux, William; Heins, Robert; Chacos, Albert; Linstrom, Lloyd; Asher, Mark; Duven, Dennis; Gruenbacher, Don; Kusterer, Thomas; Strohbehn, Kim; Morgan, Richard; , others; Published by: Published on: aug |
| 2002 |
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Yee, Jeng-Hwa; Vervack, Ronald; DeMajistre, Robert; Morgan, Frank; Carbary, James; Romick, Gerald; Morrison, Daniel; Lloyd, Steven; DeCola, Philip; Paxton, Larry; , others; Published by: Journal of Geophysical Research: Atmospheres Published on: |
| 2000 |
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Nighttime O 2 and O 3 profiles measured by MSX/UVISI using stellar occultation techniques Yee, Jeng-Hwa; DeMajistre, Robert; Vervack, Ronald; Morgan, Prank; Carbary, James; Romick, Gerald; Morrison, Daniel; Lloyd, Steven; DeCola, Philip; Paxton, Larry; , others; Published by: Washington DC American Geophysical Union Geophysical Monograph Series Published on: |
| 1996 |
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Astronomy on the Midcourse Space Experiment Price, SD; Tedesco, EF; Cohen, M; Walker, RG; Henry, RC; Moshir, M; Paxton, LJ; Witteborn, FC; Egan, MP; Shipman, RF; Published by: Published on: |
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