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Found 178 entries in the Bibliography.

Showing entries from 101 through 150

2013

Annual/semiannual variation of the ionosphere

We investigated the relationship between the systematic annual and semiannual variations in the ionosphere and thermosphere using a combination of data analysis and model simulation. A climatology of daytime peak density and height of the ionospheric F₂ layer was obtained from GPS radio occultation measurements by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) during 2007\textendash2010. These measurements were compared to simulations by the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). Model reproduction of the ionospheric annual and semiannual variations was significantly improved by imposing seasonal variation of eddy diffusion at the lower boundary, which also improves agreement with thermospheric density measurements. Since changes in turbulent mixing affect both the thermosphere and ionosphere by altering the proportion of atomic and molecular gases, these results support the proposition that composition change drives the annual/semiannual variation in both the neutral and ionized components of the coupled system.

Qian, Liying; Burns, Alan; Solomon, Stanley; Wang, Wenbin;

Published by: Geophysical Research Letters Published on: 05/2014

YEAR: 2013 DOI: 10.1002/grl.50448

annual/semiannual variations; climatology; eddy diffusion; gravity waves; neutral density and composition; NmF2

Determination of the Ionospheric Electron Density Profile from FUV Remote Sensing Measurements

A limb viewing model is established in this paper based on GUVI measurements of OI 135.6 nm nightglow and a method with Chapman function describing the distribution of ionospheric electron density is presented to obtain the ionospheric electron density profile. We apply the regularization and Newton iteration method to calculate ionospheric peak electron density and peak height with GUVI measurements, eliminating the ill condition of the weighted matrix. The ionospheric electron density profile is obtained using the calculated peak electron density and peak height as inputs. To evaluate the fidelity of the proposed algorithm in this paper, the retrieved electron density profiles are compared with those from ground-based observations. The results show that the retrieved electron density profiles agree well with those from ISR. Afterwards, the effects of magnetic storms on EDP are studied with the retrieved EDPs of the period between Sep 29 and Oct 3, 2002.

Jing, Wang; Yi, TANG; Zhi-Ge, ZHANG; Xu-Li, ZHENG; Guo-Qiang, NI;

Published by: Chinese Journal of Geophysics Published on: 03/2013

YEAR: 2013 DOI: 10.1002/cjg2.20011

Electron density profile; Far ultraviolet spectrum remote sensing; GUVI; Ionosphere

Observing the mid-and low-latitude ionosphere-global UV remote sensing

Paxton, LJ; Kil, H; Miller, ES; Comberiate, J; Schaefer, RK; Zhang, Y; Team, GUVI; , others;

Published by: Published on:

YEAR: 2013 DOI:

The Mesoscale Ionospheric Simulation Testbed (MIST) Regional Data Assimilation Model

Comberiate, J; Kelly, MA; Miller, E; Paxton, L;

Published by: Published on:

YEAR: 2013 DOI:

UV Remote Sensing Data Products-Turning Data Into Knowledge

Weiss, M; Paxton, L; Schaefer, RK; Comberiate, J; Hsieh, SW; Romeo, G; Wolven, BC; Zhang, Y;

Published by: Published on:

YEAR: 2013 DOI:

Ultraviolet Observations of the Equatorial Ionosphere at the Terminator

Miller, ES; Comberiate, J; Paxton, LJ;

Published by: Published on:

YEAR: 2013 DOI:

2012

The effects of Corotating interaction region/High speed stream storms on the thermosphere and ionosphere during the last solar minimum

Burns, A.G.; Solomon, S.C.; Qian, L.; Wang, W.; Emery, B.A.; Wiltberger, M.; Weimer, D.R.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-07-2012

YEAR: 2012 DOI: 10.1016/j.jastp.2012.02.006

Anomalously low geomagnetic energy inputs during 2008 solar minimum

Deng, Yue; Huang, Yanshi; Solomon, Stan; Qian, Liying; Knipp, Delores; Weimer, Daniel; Wang, Jing-Song;

Published by: Journal of Geophysical Research Published on: Jan-01-2012

YEAR: 2012 DOI: 10.1029/2012JA018039

Daytime climatology of ionospheric N _m F ₂ and h _m F ₂ from COSMIC data

Burns, A.; Solomon, S.; Wang, W.; Qian, L.; Zhang, Y.; Paxton, L.;

Published by: Journal of Geophysical Research Published on: Jan-01-2012

YEAR: 2012 DOI: 10.1029/2012JA017529

Modeling studies of the impact of high-speed streams and co-rotating interaction regions on the thermosphere-ionosphere

Solomon, Stanley; Burns, Alan; Emery, Barbara; Mlynczak, Martin; Qian, Liying; Wang, Wenbin; Weimer, Daniel; Wiltberger, Michael;

Published by: Journal of Geophysical Research Published on: Jan-01-2012

YEAR: 2012 DOI: 10.1029/2011JA017417

Analyzing the hemispheric asymmetry in the thermospheric density response to geomagnetic storms

The thermospheric densities derived by CHAMP/STAR accelerometer within the time period from 01 May 2001 to 31 December 2007 are utilized to investigate the hemispheric asymmetry in response to strong storm driving conditions. The geomagnetic storms of 03\textendash07 April 2004 are first studied since the storms occurred close to the vernal equinox, allowing the seasonal asymmetry to be eliminated to the greatest extent. The averaged density enhancements in the southern polar region were much larger than that in the northern polar region. The comparisons of density versus Dst and Apindex indicate a strong linear dependence with the slopes of the fitted lines in the southern hemisphere being 50\% greater than that in the northern hemisphere. This effect can possibly be attributed to the non-symmetric geomagnetic field. 102 storm events are used to conduct a statistical analysis. For each storm, a linear fit is made between the averaged mass density and theDst and Ap indices independently in each hemisphere. The seasonal variation of the intercepts and the slopes of the fitted lines are further explored. The baseline is strongly dependent on season, with the hemisphere receiving the larger amount of sunlight having larger density. The slopes showed considerable hemispheric differences around the vernal equinox yet no statistical differences around other seasons. It is speculated that competing mechanisms cancel each other during the solstices, while during the equinoxes, the lower magnetic field in the southern hemisphere may allow stronger ion flows, thereby causing more Joule heating. It is uncertain why the vernal equinox would be favored in this explanation though.

Ercha, A.; Ridley, Aaron; Zhang, Donghe; Xiao, Zuo;

Published by: Journal of Geophysical Research Published on: 08/2012

YEAR: 2012 DOI: 10.1029/2011JA017259

Geomagnetic storms; hemispheric asymmetry; thermospheric density

Extreme Ultraviolet Variability Experiment (EVE) on~the~Solar Dynamics Observatory (SDO): Overview~of~Science Objectives, Instrument Design, Data~Products, and Model Developments

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth\textquoterights upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105\ nm with unprecedented spectral resolution (0.1\ nm), temporal cadence (ten seconds), and accuracy (20\%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37\ nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105\ nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39\ nm, and a MEGS-Photometer measures the Sun\textquoterights bright hydrogen emission at 121.6\ nm. The EVE data products include a near real-time space-weather product (Level\ 0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15\ minutes. The EVE higher-level products are Level\ 2 with the solar EUV irradiance at higher time cadence (0.25\ seconds for photometers and ten seconds for spectrographs) and Level\ 3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth\textquoterights ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.

Woods, T.; Eparvier, F.; Hock, R.; Jones, A.; Woodraska, D.; Judge, D.; Didkovsky, L.; Lean, J.; Mariska, J.; Warren, H.; McMullin, D.; Chamberlin, P.; Berthiaume, G.; Bailey, S.; Fuller-Rowell, T.; Sojka, J.; Tobiska, W.; Viereck, R.;

Published by: Solar Physics Published on: 01/2012

YEAR: 2012 DOI: 10.1007/s11207-009-9487-6

EVE; SDO; Solar EUV irradiance; Space weather research

Space-Based Three-Dimensional Imaging of Equatorial Plasma Bubbles: Advancing the Understanding of Ionospheric Density Depletions and Scintillation

Since their launches in October 2003 and October 2009, the SSUSI instruments on the DMSP F16 and F18 satellites have over 5 years of daily global observations of the nightside

Comberiate, Joseph;

Published by: Published on:

YEAR: 2012 DOI:

Space Weather Products from UV Imagers in Low Earth Orbit-Providing Key Information about the ITM Environment

Romeo, G; Paxton, LJ; Schaefer, RK; DeMajistre, R; Comberiate, J; Hsieh, SW; Miller, ES; Weiss, M; Wolven, BC; Zhang, Y;

Published by: Published on:

YEAR: 2012 DOI:

Variations in the heliospheric polar energetic neutral atom flux observed by the Interstellar Boundary Explorer

Reisenfeld, DB; Allegrini, F; Bzowski, M; Crew, GB; DeMajistre, R; Frisch, P; Funsten, HO; Fuselier, SA; Janzen, PH; Kubiak, MA; , others;

Published by: The Astrophysical Journal Published on:

YEAR: 2012 DOI:

New and Improved GUVI Data Products for ITM Research

Schaefer, RK; Paxton, LJ; DeMajistre, R; Comberiate, J; Hsieh, SW; Miller, ES; Romeo, G; Weiss, M; Wolven, BC; Zhang, Y;

Published by: Published on:

YEAR: 2012 DOI:

The seasonal changes in the relationship between neutral composition and NmF2 from 2002 to 2007

Burns, AG; Solomon, SC; Wang, W; Qian, L; Zhang, Y; Paxton, LJ;

Published by: Published on:

YEAR: 2012 DOI:

2011

GPS based TEC measurements for a period August 2008--December 2009 near the northern crest of Indian equatorial ionospheric anomaly region

KARIA, S; PATHAK, K;

Published by: Journal of Earth System Science Published on: Jan-10-2011

YEAR: 2011 DOI: 10.1007/s12040-011-0114-1

Separation of the Interstellar Boundary Explorer ribbon from globally distributed energetic neutral atom flux

Schwadron, Nathan; Allegrini, F; Bzowski, Maciej; Christian, ER; Crew, GB; Dayeh, M; DeMajistre, R; Frisch, P; Funsten, HO; Fuselier, SA; , others;

Published by: The Astrophysical Journal Published on:

YEAR: 2011 DOI:

Mutual Neutralization of Atomic Oxygen Ions Over the Course of the Solar Cycle and Its Effects on Ionospheric Remote Sensing

Comberiate, J; DeMajistre, R; Schaefer, RK; Zhang, Y; Paxton, LJ;

Published by: Published on:

YEAR: 2011 DOI:

Progress in observations and simulations of global change in the upper atmosphere

Qian, Liying; La\vstovi\vcka, Jan; Roble, Raymond; Solomon, Stanley;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2011 DOI:

2010

Coordinated UV imaging of equatorial plasma bubbles using TIMED/GUVI and DMSP/SSUSI

Comberiate, Joseph; Paxton, L.;

Published by: Space Weather Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2009SW000546

Equatorial ionosphere; ionospheric irregularities; scintillation

Dynamic variability in F-region ionospheric composition at auroral arc boundaries

Zettergren, M.; Semeter, J.; Burnett, B.; Oliver, W.; Heinselman, C.; Blelly, P.-L.; Diaz, M.;

Published by: Annales Geophysicae Published on: Jan-01-2010

YEAR: 2010 DOI: 10.5194/angeo-28-651-2010

Global Ultraviolet Imager equatorial plasma bubble imaging and climatology, 2002--2007

A comprehensive database of plasma bubble reconstructions is under development, with results reported here from more than 5 years of Global Ultraviolet Imager (GUVI) data. Climatological statistics of plasma bubble occurrence from this database are presented, including the effects of longitudinal, seasonal, geomagnetic, and solar cycle variations on plasma bubble occurrence. The relationship between the latitudinal separation and peak electron density values of the equatorial arcs and plasma bubble occurrence is also discussed. Since its launch on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite in December 2001, GUVI has more than 7 years of observations of the nightside equatorial ionosphere. GUVI is capable of detecting and imaging plasma bubbles within the northern and southern equatorial arcs. An automated algorithm was developed to locate the peaks of the equatorial arcs and detect the presence of equatorial plasma bubbles. This algorithm was integrated with a tomographic imaging model and a statistical inversion technique to reconstruct electron density and produce multidimensional images of plasma depletion structures.

Comberiate, Joseph; Paxton, L.;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2009JA014707

Model simulation of thermospheric response to recurrent geomagnetic forcing

Qian, Liying; Solomon, Stanley; Mlynczak, Martin;

Published by: Journal of Geophysical Research Published on: Jan-01-2010

YEAR: 2010 DOI: 10.1029/2010JA015309

Enhanced UV Data Products-Observing the Ionosphere in Greater Fidelity

Wolven, BC; Paxton, LJ; Comberiate, J; Hsieh, SW; , Nylund; Schaefer, RK; Selby, C; Smith, D; Weiss, M; Zhang, Y;

Published by: Published on:

YEAR: 2010 DOI:

Equatorial Plasma Bubble Climatology and Scintillation Forecasting from DMSP/SSUSI

Comberiate, J; Paxton, LJ;

Published by: Published on:

YEAR: 2010 DOI:

LWS FST: Determine and Quantify the Responses of Atmospheric/Ionospheric Composition and Temperature to Solar XUV Spectral Variability and Energetic Particles

Talaat, Elsayed; Fuller-Rowell, Tim; Qian, Liying; Richards, Phil; Ridley, Aaron; Burns, Alan; Bernstein, Dennis; Chamberlin, Phillip; Fedrizzi, Mariangel; Hsieh, Syau-Yun; , others;

Published by: 38th COSPAR Scientific Assembly Published on:

YEAR: 2010 DOI:

Estimating The Forces That Drive Ionosphere And Thermosphere Variability: Continuous Data And Assimilative Modeling

onosphere-thermosphere science has long been hampered by a lack of measurements of the underlying forces that determine plasma structure. These forces include electric fields, thermospheric composition, winds and solar EUV irradiance. All of these forces are dynamic quantities and of great importance to the underlying science. The rapid proliferation of electron density and total electron content measurements from ground and space-borne GPS receivers and other instruments suggests a great potential in the following indirect approach to estimating these forces: developing a model-based approach to retrieving the forces from the electron density structure and dynamics. The research community has just begun to explore such an approach, which addresses significant science questions previously out of reach.

Mannucci, Anthony; Pi, Xiaoqing; Butala, Mark; Stephens, Phil; Wilson, Brian; Komjathy, Attila; Iijima, Byron; Akopian, Vardan; Dumett, Miguel;

Published by: To advocate developing a model-based approach to retrieving the driving forces from measurements of electron density structure and dynamics Published on:

YEAR: 2010 DOI:

Canary: Ion spectroscopy for ionospheric sensing

Feldmesser, HS; Darrin, MAG; Osiander, R; Paxton, LJ; Rogers, AQ; Marks, JA; McHarg, MG; Balthazor, RL; Krause, LH; FitzGerald, JG;

Published by: Published on:

YEAR: 2010 DOI:

2009

Estimation of electron densities in the lower thermosphere from GUVI 135.6 nm tomographic inversions in support of SpreadFEx

Kamalabadi, F.; Comberiate, J.; Taylor, M.; Pautet, P.-D.;

Published by: Annales Geophysicae Published on: Jan-01-2009

YEAR: 2009 DOI: 10.5194/angeo-27-2439-2009

Low-frequency whistler waves and shocklets observed at quasi-perpendicular interplanetary shocks

Wilson, L.; Cattell, C.; Kellogg, P.; Goetz, K.; Kersten, K.; Kasper, J.; Szabo, A.; Meziane, K.;

Published by: Journal of Geophysical Research Published on: Jan-01-2009

YEAR: 2009 DOI: 10.1029/2009JA014376

Seasonal variation of thermospheric density and composition

Thermospheric neutral density and composition exhibit a strong seasonal variation, with maxima near the equinoxes, a primary minimum during northern hemisphere summer, and a secondary minimum during southern hemisphere summer. This pattern of variation is described by thermospheric empirical models. However, the mechanisms are not well understood. The annual insolation variation due to the Sun-Earth distance can cause an annual variation, large-scale interhemispheric circulation can cause a global semiannual variation, and geomagnetic activity can also have a small contribution to the semiannual amplitude. However, simulations by the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) indicates that these seasonal effects do not fully account for the observed annual/semiannual amplitude, primarily because of the lack of a minimum during northern hemisphere summer. A candidate for causing this variation is a change in composition, driven by eddy mixing in the mesopause region. Other observations and model studies suggest that eddy diffusion in the mesopause region has a strong seasonal variation, with eddy diffusion larger during solstices than equinoxes, and stronger turbulence in summer than in winter. A seasonal variation of eddy diffusion compatible with this description is obtained. Simulations show that when this function is imposed at the lower boundary of the TIE-GCM, neutral density variation consistent with satellite drag data and O/N₂ consistent with measurements by TIMED/GUVI, are obtained. These model-data comparisons and analyses indicate that turbulent mixing originated from the lower atmosphere may contribute to seasonal variation in the thermosphere, particularly the asymmetry between solstices that cannot be explained by other mechanisms.

Qian, Liying; Solomon, Stanley; Kane, Timothy;

Published by: Journal of Geophysical Research Published on: 01/2009

YEAR: 2009 DOI: 10.1029/2008JA013643

eddy diffusion; thermospheric annual/semiannual variation; thermospheric density and composition

Behavior of the Ionosphere and Thermosphere at Solar Minimum: Data and Model Comparisons and Analysis

Paxton, LJ; Zhang, Y; Kil, H; Schaefer, RK; Comberiate, J; Christensen, AB;

Published by: Published on:

YEAR: 2009 DOI:

Putting Space Physics Data Facility (SPDF) Services to Good Use

Candey, RM; Bilitza, D; Chimiak, R; Cooper, JF; Garcia, LN; Harris, B; Johnson, RC; King, JH; Kovalick, T; Leckner, H; , others;

Published by: Published on:

YEAR: 2009 DOI:

Putting Space Physics Data Facility (SPDF) Services to Good Use

Candey, RM; Bilitza, D; Chimiak, R; Cooper, JF; Garcia, LN; Harris, B; Johnson, RC; King, JH; Kovalick, T; Leckner, H; , others;

Published by: Published on:

YEAR: 2009 DOI:

Ionospheric control of auroral occurrence

Kan, Liou; Yongliang, Zhang; Patrick, Newell; Larry, Paxton;

Published by: Published on:

YEAR: 2009 DOI:

Global observations of the equatorial ionosphere by UV remote sensing

Paxton, Larry; Comberiate, Joseph; Kil, Hyosub; Schaefer, Robert; Wolven, Brian; Zhang, Yongliang; Morrison, Daniel;

Published by: Published on:

YEAR: 2009 DOI:

Space-and Ground-Based Observations of Solar Cycle and Local Time Dependence of Equatorial Plasma Bubble Activity

Miller, ES; Comberiate, J; Makela, JJ; Paxton, LJ; Kelley, MC; Groves, KM; Tsunoda, RT;

Published by: Published on:

YEAR: 2009 DOI:

Coordinated Ground-and Space-based 3-D Electron Density Reconstruction and Plasma Bubble Imaging

Comberiate, J; Miller, ES; Paxton, LJ; Makela, JJ; Kelley, MC;

Published by: Published on:

YEAR: 2009 DOI:

Global Ionospheric Structure Imaged by FORMOSAT-3/COSMIC: Early Results.

A new era of study ing the ion o spheric space weather ef fects has come af ter launch of the in no va tive sat el lite con stel la tion, named as Formosa Sat el lite 3 or Con stel la tion Ob

Lin, Chien-Hung; Liu, Jann-Yenq; Hsiao, Chun-Chieh; Liu, Chao-Han; Cheng, Chio-Zong; Chang, Po-Ya; Tsai, Ho-Fang; Fang, Tzu-Wei; Chen, Chia-Hung; Hsu, Mei-Lan;

Published by: Terrestrial, Atmospheric \& Oceanic Sciences Published on:

YEAR: 2009 DOI:

Equatorial and low-latitude ionosphere-thermosphere system response to the space weather event of August 2005

, Sreeja; Ravindran, Sudha; Pant, Tarun; Devasia, CV; Paxton, LJ;

Published by: Journal of Geophysical Research: Space Physics Published on:

YEAR: 2009 DOI:

3-D Ionospheric Electron Density Reconstructions and Radio Propagation Modeling Using DMSP/SSUSI

McMahon, Erin; Comberiate, Joseph; Paxton, Larry; Kelly, Michael;

Published by: Published on:

YEAR: 2009 DOI:

2008