GUVI Biblio





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Found 748 entries in the Bibliography.


Showing entries from 351 through 400


2014

Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity

Responses of the lower thermospheric temperature to the 9 day and 13.5 day oscillations of recurrent geomagnetic activity and solar EUV radiation have been investigated using neutral temperature data observed by the TIMED/SABER (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) instrument and numerical experiments by the NCAR-TIME-GCM (National Center for Atmospheric Research\textendashthermosphere-ionosphere-mesosphere electrodynamics\textendashgene ...

Jiang, Guoying; Wang, Wenbin; Xu, JiYao; Yue, Jia; Burns, Alan; Lei, Jiuhou; Mlynczak, Martin; Rusell, James;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.610.1002/2013JA019406

13.5 day variation; 9 day variation; Joule heating; lower thermospheric temperature; recurrent geomagnetic activity; solar EUV radiation

On the solar cycle variation of the winter anomaly

Constellation Observing System for Meteorology, Ionosphere and Climate, Ionosonde, and Global Ultraviolet Imager data have been used to investigate the solar cycle changes in the winter anomaly (the winter anomaly is defined as the enhancement of the F2 peak electron density in the winter hemisphere over that in the summer hemisphere) in the last solar cycle. There is no winter anomaly in solar minimum, and an enhancement of about 50\% in winter over summer ones on the same day of the year at solar max ...

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

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.610.1002/2013JA019552

Anomaly; Cycle; Ionosphere

Climatology of global gravity wave activity and dissipation revealed by SABER/TIMED temperature observations

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 he ...

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

Strong ionospheric field-aligned currents for radial interplanetary magnetic fields

The present work has investigated the configuration of field-aligned currents (FACs) during a long period of radial interplanetary magnetic field (IMF) on 19 May 2002 by using high-resolution and precise vector magnetic field measurements of CHAMP satellite. During the interest period IMF By and Bz are weakly positive and Bx keeps pointing to the Earth for almost 10 h. The geomagnetic indices Dst is about -40 ...

Wang, Hui; Lühr, Hermann; Shue, Jih-Hong; Frey, Harald.; Kervalishvili, Guram; Huang, Tao; Cao, Xue; Pi, Gilbert; Ridley, Aaron;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2014

YEAR: 2014     DOI: 10.1002/2014JA019951

air upwelling; field-aligned currents; radial interplanetary magnetic field

An analysis of the quiet time day-to-day variability in the formation of postsunset equatorial plasma bubbles in the Southeast Asian region

Presented is an analysis of the occurrence of postsunset Equatorial Plasma Bubbles (EPBs) detected using a Global Positioning System (GPS) receiver at Vanimo. The three year data set shows that the EPB occurrence maximizes (minimizes) during the equinoxes (solstices), in good agreement with previous findings. The Vanimo ionosonde station is used with the GPS receiver in an analysis of the day-to-day EPB occurrence variability during the 2000 equinox period. A superposed epoch analysis (SEA) reveals that the altitude, and ...

Carter, B.; Yizengaw, E.; Retterer, J.; Francis, M.; Terkildsen, M.; Marshall, R.; Norman, R.; Zhang, K.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.410.1002/2013JA019570

equatorial plasma bubbles; GPS scintillation; Ionosphere

Ionization due to electron and proton precipitation during the August 2011 storm

The parameterizations of monoenergetic particle impact ionization in Fang et al. (2010) (Fang2010) and Fang et al. (2013) (Fang2013) are applied to the complex energy spectra measured by DMSP F16 satellite to calculate the ionization rates from electron and ion precipitations for a Northern Hemisphere pass from 0030 UT to 0106 UT on 6 August 2011. Clear enhancement of electron flux is found in the polar cap. The mean electron energy in the polar cap is mostly above 100 eV, while the mean energy in the auroral zone is typi ...

Huang, Yanshi; Huang, Cheryl; Su, Yi-Jiun; Deng, Yue; Fang, Xiaohua;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2014

YEAR: 2014     DOI: 10.1002/2013JA019671

Fang 2010 parameterization; Fang 2013 parameterization; particle impact ionization; polar cap

Space shuttle exhaust plumes in the lower thermosphere: Advective transport and diffusive spreading

The space shuttle main engine plume deposited between 100 and 115\ km altitude is a valuable tracer for global-scale dynamical processes. Several studies have shown that this plume can reach the Arctic or Antarctic to form bursts of polar mesospheric clouds (PMCs) within a few days. The rapid transport of the shuttle plume is currently not reproduced by general circulation models and is not well understood. To help delineate the issues, we present the complete satellite datasets of shuttle plume observations by the S ...

Stevens, Michael; Lossow, Stefan; Siskind, David; Meier, R.R.; Randall, Cora; Russell, James; Urban, Jo; Murtagh, Donal;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 02/2014

YEAR: 2014     DOI: 10.1016/j.jastp.2013.12.004

Atmospheric dynamics; Lower thermosphere; Polar mesospheric clouds; Space shuttle exhaust

A study on ionospheric scintillation near the EIA crest in relation to equatorial electrodynamics

Equatorial electrojet (EEJ) data, which are considered as a proxy index of equatorial electric field, are analyzed in conjunction with equatorial ionosonde, total electron content (TEC) and scintillation data near the equatorial ionization anomaly (EIA) crest for the equinoctial months of high solar activity years (2011\textendash2012) to identify any precursor index of postsunset evolution of equatorial electron density irregularities and subsequent occurrence of scintillation near the northern EIA crest. Only geomagneti ...

Chatterjee, S.; Chakraborty, S.; Veenadhari, B.; Banola, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 02/2014

YEAR: 2014     DOI: 10.1002/2013JA019466

scintillations in relation to equatorial electrodynamics

Correction of astigmatism and coma using analytic theory of aberrations in imaging spectrometer based on concentric off-axis dual reflector system

A specific imaging spectrometer based on a concentric off-axis dual reflector system is proposed, free of astigmatism and coma. The described imaging spectrometer consists of four spherical mirrors and a plane grating. The analytic theory of aberrations and the optical path-length concept are used to derive the astigmatism elimination and coma removal. It is shown that the astigmatism in these imaging spectrometers is eliminated by characterizing three angles, and the coma is corrected when unequal mirror radii are config ...

Chen, Ting; Tang, Yi; Zhang, Li; Chang, Yue; Zheng, Cheng;

Published by: Applied Optics      Published on: 01/2014

YEAR: 2014     DOI: 10.1364/AO.53.000565

The International Reference Ionosphere: Rawer\textquoterights IRI and its status today

When the Committee on Space Research (COSPAR) initiated the International Reference Ionosphere (IRI) project in 1968 it wisely selected K. Rawer as its first Chairperson. With a solid footing and good contacts in both the ground-based and space-based ionospheric communities he was ideally suited to pull together colleagues and data from both communities to help build the first version of the IRI. He assembled a team of 20+ international ionospheric experts in the IRI Working Group and chaired and directed the group from 1 ...

Bilitza, D.;

Published by: Advances in Radio Science      Published on: 01/2014

YEAR: 2014     DOI: 10.5194/ars-12-231-2014

IRI

Spherical cap harmonic analysis of the Arctic ionospheric TEC for one solar cycle

Precise knowledge of the Arctic ionosphere total electron content (TEC) and its variations has scientific relevance due to the unique characteristics of the polar ionosphere. Understanding the Arctic TEC is also important for precise positioning and navigation in the Arctic. This study utilized the spherical cap harmonic analysis (SCHA) method to map the Arctic TEC for the most recent solar cycle from 2000 to 2013 and analyzed the distributions and variations of the Arctic TEC at different temporal and spatial scales. Eve ...

Liu, Jingbin; Chen, Ruizhi; An, Jiachun; Wang, Zemin; Hyyppa, Juha;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2014

YEAR: 2014     DOI: 10.1002/2013JA019501

Arctic navigation; ionosphere mapping and prediction; polar ionosphere; regional ionosphere model; spherical cap harmonic analysis

Traveling ionospheric disturbances observed at South African midlatitudes during the 29\textendash31 October 2003 geomagnetically disturbed period

This paper presents traveling ionospheric disturbances (TIDs) observations from GPS measurements over the South African region during the geomagnetically disturbed period of 29\textendash31 October 2003. Two receiver arrays, which were along two distinct longitudinal sectors of about 18\textdegree-20\textdegree and 27\textdegree-28\textdegree were used in order to investigate the amplitude, periods and virtual propagation characteristics of the storm induced ionospheric disturbances. The study revealed a large sudden TEC ...

Katamzi, Zama; Habarulema, John;

Published by: Advances in Space Research      Published on: 01/2014

YEAR: 2014     DOI: 10.1016/j.asr.2013.10.019

geomagnetic storm; Substorm; Total electron content (TEC); Traveling ionospheric disturbances (TIDs)

Variations of the neutral temperature and sodium density between 80 and 107 km above Troms\o during the winter of 2010-2011 by a new solid-state sodium lidar

A new solid-state sodium lidar installed at Ramfjordmoen, Troms\o (69.6\textdegreeN, 19.2\textdegreeE), started observations of neutral temperature together with sodium density in the mesosphere-lower thermosphere (MLT) region on 1 October 2010. The new lidar provided temperature data with a time resolution of 10 min and with good quality between \~80 and \~105 km from October 2010 to March 2011. This paper aims at introducing the new lidar with its observational results obtained over the first 6 months of observations. W ...

Nozawa, S.; Kawahara, T.; Saito, N.; Hall, C.; Tsuda, T.; Kawabata, T.; Wada, S.; Brekke, A.; Takahashi, T.; Fujiwara, H.; Ogawa, Y.; Fujii, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2014

YEAR: 2014     DOI: 10.1002/2013JA019520

Joule heating; neutral temperature; polar MLT; sodium lidar

Earthquake Prediction Research Using Radio Tomography of the Ionosphere

Under development since its invention in 1990 as an ancillary application of ionospheric radio-tomography (RT), a new earthquake (EQ) prediction system is being evaluated. It has already been deployed along the United States West Coast, from Vancouver in Canada to San Diego in Southern California, and is currently undergoing Beta testing. This Chapter addresses RT\textendashEQ prediction concepts, the underlying RT theory, evolution and implementation, and a few examples of the Beta test system\textquoterights performance ...

Kunitsyn, Vyacheslav; Andreeva, Elena; Nesterov, Ivan; Padokhin, Artem; Gribkov, Dmitrii; Rekenthaler, Douglas;

Published by:       Published on:

YEAR: 2014     DOI: 10.1007/978-3-319-02207-9_15

Energetics and Composition in the Thermosphere

Burns, AG; Wang, W; Solomon, SC; Qian, L;

Published by: Modeling the Ionosphere-Thermosphere System      Published on:

YEAR: 2014     DOI:

Ionospheric imaging using merged ultraviolet airglow and radio occultation data

The Limb-imaging Ionospheric and Thermospheric Extreme-ultraviolet Spectrograph (LITES) and GPS Radio Occultation and Ultraviolet Photometry-Colocated (GROUP-C) experiments are being considered for flight aboard the Space Test Program Houston 5 (STP-H5) experiment pallet to the International Space Station (ISS). LITES is a compact imaging spectrograph that makes one-dimensional images of atmospheric and ionospheric ultraviolet (60-140 nm) airglow above the limb of the Earth. The LITES optical design is advantageous in tha ...

Stephan, Andrew; Budzien, Scott; Finn, Susanna; Cook, Timothy; Chakrabarti, Supriya; Powell, Steven; Psiaki, Mark;

Published by:       Published on:

YEAR: 2014     DOI: 10.1117/12.2061420

Modelling ionospheric effects for L band GNSS receivers at high latitudes

The main objective of this study was to figure out a relationship between space weather environment phenomena (linked to solar and geomagnetic activity) and ionospheric events that impact L-band operating satellite systems (scintillations, electron content gradients), especially satellite navigation services, in the Nordic European area. A simple empirical model to forecast index of rate of change of the total electron content (ROTI) at high latitude has been developed associated with Kp geomagnetic prediction and the use ...

Boscher, D.; Carvalho, F.; Fabbro, V.; Lemorton, J.; Fleury, R.;

Published by:       Published on:

YEAR: 2014     DOI: 10.1109/EuCAP.2014.6902380

high latitude; Ionosphere; radiowave propagation; scintillation; solar and geomagnetic activity

Polar cap arcs correlated with solar wind entry at the high latitude magnetosphere

Polar cap arcs are sun-aligned aurora structures occurring during northward turnings of the Interplanetary Magnetic Field (IMF) Bz component. At the same time, a new region of solar wind entry at the high latitude magnetosphere, tailward of the cusp region, was found recently at the periods of northward IMF Bz. We propose a study to see the relationship of these entry events with the transpolar arc formation. Data of Global Ultraviolet Imager (GUVI) onboard TIMED mission is examined to see the transp ...

Mailyan, B.; Shi, Q.; Gou, X.;

Published by:       Published on:

YEAR: 2014     DOI: 10.1109/URSIGASS.2014.6929926

aurora interplanetary; GUVI; magnetic fields; magnetosphere; solar wind; TIMED

Statistical relationship between large-scale upward field-aligned currents and electron precipitation

Simultaneous observations of Birkeland currents by the constellation of Iridium satellites and N2 Lyman\textendashBirge\textendashHopfield (LBH) auroral emissions measured by the Global Ultraviolet Imager (GUVI) onboard the Thermosphere, Ionosphere, and Mesosphere Energetics and Dynamics (TIMED) satellite are used to establish relationships between large-scale upward field-aligned currents and electron precipitation during stable current configurations. The electron precipitation was inferred from GUVI data using a statis ...

Korth, Haje; Zhang, Yongliang; Anderson, Brian; Sotirelis, Thomas; Waters, Colin;

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

YEAR: 2014     DOI: 10.1002/2014JA019961

Birkeland Currents; Auroral Emissions; electron precipitation; Current-Precipitation Relationship; Current-Voltage Relationship

2013

Lyman α airglow emission: Implications for atomic hydrogen geocorona variability with solar cycle

Satellite-based measurements of geocoronal Lyman α (Lyα) emission at 121.6 nm, created through multiple scattering of solar Lyαphotons by atomic hydrogen, offer a valuable means of inferring the hydrogen abundance, [H], in the terrestrial thermosphere and exosphere on a global, long-term basis. We present initial results from an analysis of Lyα radiance measurements acquired across the Earth\textquoterights limb from 2002 to 2007 by the Global UltraV ...

Waldrop, L.; Paxton, L.;

Published by: Journal of Geophysical Research: Space Physics      Published on: Jan-09-2013

YEAR: 2013     DOI: 10.1002/jgra.50496

atmospheric escape; hydrogen geocorona; radiative transport

On the fast zonal transport of the STS-121 space shuttle exhaust plume in the lower thermosphere

Meier et al. (2011) reported rapid eastward transport of the STS-121 space shuttle (launch: July 4, 2006) main engine plume in the lower thermosphere, observed in hydrogen Lyman α images by the GUVI instrument onboard the TIMED satellite. In ord ...

Yue, Jia; Liu, Han-Li; Meier, R.R.; Chang, Loren; Gu, Sheng-Yang; , Russell;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: Jan-03-2013

YEAR: 2013     DOI: 10.1016/j.jastp.2012.12.017

Modeling; thermosphere; Transport; Wind jet

The effect of the 135.6 nm emission originated from the ionosphere on the TIMED/GUVI O/N 2 ratio

The column number density ratio of atomic oxygen to molecular nitrogen (O/N2\ ratio) provided by the Global Ultraviolet Imager (GUVI) onboard the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite has been used as a diagnostic of the thermospheric neutral composition. However, a recent study claimed that the GUVI O/N2\ ratio is not a pure thermospheric parameter in low latitudes during periods of low geomagnetic activity. This study quantifies the O/N2 ...

Kil, H.; Lee, W.; Shim, J.; Paxton, L.J.; Zhang, Y.;

Published by: Journal of Geophysical Research: Space Physics      Published on: Jan-02-2013

YEAR: 2013     DOI: 10.1029/2012JA018112

The effect of geomagnetic-storm-induced enhancements to ionospheric emissions on the interpretation of the TIMED/GUVI O/N 2 ratio

[1]\ We examine the consequence of enhanced atomic oxygen (OI) 135.6 nm emissions due to the recombination of O+ with electrons on the column number density ratio of atomic oxygen to molecular nitrogen (O/N2 ratio) provided by Global Ultraviolet Imager (GUVI) on board the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics satellite. GUVI O/N2 ratio is derived from the measurements of OI 135.6 nm and N2 Lyman-Birge-Hopfield airglow emissions. The OI 135.6 nm emissi ...

Lee, Woo; Kil, Hyosub; Paxton, Larry; Zhang, Yongliang; Shim, Ja;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2013

YEAR: 2013     DOI: 10.1002/2013JA019132

geomagnetic storm; GUVI O/N2 ratio; ionospheric effect

Estimating the propagation characteristics of large-scale traveling ionospheric disturbances using ground-based and satellite data

In this article, the propagation characteristics of large-scale traveling ionospheric disturbances (LS TIDs) are estimated during the geomagnetic storm periods of 14\textendash16 May 2005 and 25\textendash27 September 2011 over South Africa. One and two GPS arrays have been independently considered for the storms of 15 May 2005 and 26 September 2011, respectively. The average periods of dominant modes (≈ 2.5\textendash3.5h) in the time series data were determined by applying wavelet analysis on both ionosonde and GPS da ...

Habarulema, John; Katamzi, Zama; McKinnell, Lee-Anne;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2013

YEAR: 2013     DOI: 10.1002/2013JA018997

characteristics of large scale TIDs; Geomagnetic storms; ionospheric irregularities

The Ionospheric Bubble Index deduced from magnetic field and plasma observations onboard Swarm

In the post-sunset tropical ionospheric F-region plasma density often exhibits depletions, which are usually called equatorial plasma bubbles (EPBs). In this paper we give an overview of the Swarm Level 2 Ionospheric Bubble Index (IBI), which is a standard scientific data of the Swarm mission. This product called L2-IBI is generated from magnetic field and plasma observations onboard Swarm, and gives information as to whether a Swarm magnetic field observation is affected by EPBs. We validate the performance of the L2-IBI ...

Park, J.; Noja, M.; Stolle, C.; Lühr, H.;

Published by: Earth, Planets and Space      Published on: 11/2014

YEAR: 2013     DOI: 10.5047/eps.2013.08.005

Equatorial ionosphere; Plasma irregularity; topside ionosphere

Equatorial ionization anomaly development as studied by GPS TEC and foF2 over Brazil: A comparison of observations with model results from SUPIM and IRI-2012

The equatorial ionization anomaly (EIA) development is studied using the total electron content (TEC) observed by the Global Positioning System (GPS) satellites, the F2-layer critical frequency (foF2) as measured by digisondes operated in the Brazilian sector, and by model simulation using the SUPIM (Sheffield University Plasmasphere Ionosphere Model). We have used two indices based on foF2 and TEC to represent the strength of the EIA Southern Anomaly Crest (SAC), which are denoted, respectively, by SAC( ...

Nogueira, P.A.B.; Abdu, M.A.; Souza, J.R.; Batista, I.S.; Bailey, G.J.; Santos, A.M.; Takahashi, H.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 11/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.08.013

Equatorial anomaly; foF2; Ionospheric modeling; TEC

Aerodynamic Analysis Based on Challenging Minisatellite Payload Satellite Lift-to-Drag Measurements

A lift-to-drag ratio analysis is performed based on accelerometer measurements made by the Challenging Minisatellite Payload satellite to investigate the nature of gas-surface interactions taking place in orbit. The results described are for the November\ 2002 satellite yaw maneuver. At this time, the satellite flew at a mean altitude of 407\ km. Two types of gas\textendashsurface interaction are considered in the analysis. The first is a cosine (fully diffuse) reflection model with incomplete energy acc ...

Pilinski, Marcin; Argrow, Brian;

Published by: Journal of Spacecraft and Rockets      Published on: 11/2013

YEAR: 2013     DOI: 10.2514/1.A32394

Ionospheric symmetry caused by geomagnetic declination over North America

We describe variations in total electron content (TEC) in the North American sector exhibiting pronounced longitudinal progression and symmetry with respect to zero magnetic declination. Patterns were uncovered by applying an empirical orthogonal function (EOF) decomposition procedure to a 12 year ground-based American longitude sector GPS TEC data set. The first EOF mode describes overall average TEC, while the strong influence of geomagnetic declination on the midlatitude ionosphere is found in the second EOF mode (or t ...

Zhang, Shun-Rong; Chen, Ziwei; Coster, Anthea; Erickson, Philip; Foster, John;

Published by: Geophysical Research Letters      Published on: 10/2014

YEAR: 2013     DOI: 10.1002/grl.v40.2010.1002/2013GL057933

geomagnetic field; midlatitude ionosphere; thermospheric winds; total electron content

GPS TEC near the crest of the EIA at 95\textdegreeE during the ascending half of solar cycle 24 and comparison with IRI simulations

Total electron content (TEC) data obtained from GPS dual frequency measurements during the ascending half of the solar cycle 24 from 2009 to 2012 over Dibrugarh (27.5\textdegreeN, 94.9\textdegreeE; 17.6\textdegreeN MLAT) have been used to study the diurnal, seasonal, annual and solar cycle variation of TEC. The measurements reported here are for the first time from the location situated at the poleward edge of the northern equatorial ionization anomaly (EIA) and within the peak region of the longitudinal wave number 4 (WN ...

Bhuyan, Pradip; Hazarika, Rumajyoti;

Published by: Advances in Space Research      Published on: 10/2013

YEAR: 2013     DOI: 10.1016/j.asr.2013.06.029

Equatorial ionosphere; GPS; Ionosphere; IRI; TEC

Ion-neutral coupling during deep solar minimum

The equatorial ionosphere under conditions of deep solar minimum exhibits structuring due to tidal forces. Data from instruments carried by the Communication/Navigation Outage Forecasting System (C/NOFS) which was launched in April 2008 have been analyzed for the first 2 years following launch. The Planar Langmuir Probe (PLP), Ion Velocity Meter (IVM) and Vector Electric Field Investigation (VEFI) all detect periodic structures during the 2008\textendash2010 period which appear to be tides. However when the tidal features ...

Huang, Cheryl; Roddy, Patrick; Sutton, Eric; Stoneback, Russell; Pfaff, Robert; Gentile, Louise; Delay, Susan;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 10/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2012.11.009

Equatorial ionosphere; Nonmigrating tides; Plasma depletions; thermosphere

The anomalous ionosphere between solar cycles 23 and 24

The solar minimum period during 2008\textendash2009 was characterized by lower thermospheric density than the previous solar minimum and lower than any previously measured. Recent work used the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model to show that the primary cause of density changes from 1996 to 2008 was a small reduction in solar extreme ultraviolet (EUV) irradiance, causing a decrease in thermospheric temperature and hence a contracted thermosphere. There are similar effects in the ionosph ...

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

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2013

YEAR: 2013     DOI: 10.1002/jgra.v118.1010.1002/jgra.50561

climate; Ionosphere; irradiance; solar; thermosphere; ultraviolet

Theoretical tools for studies of low-frequency thermospheric variability

[1]\ This paper supports studies of low-frequency variability (LFV) within the thermosphere by deriving approximate integral and closed-form solutions of a nontrivial model of thermospheric temperature, density, and composition depending on altitude and time. We also provide a paradigm for applying dimensional analysis in such studies. The domain is the region between the mesopause and the exobase. The solutions emphasize the connectedness of the thermosphere, i.e., nonlocal influences of LFV in key physical paramete ...

Picone, J.; Meier, R.; Emmert, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2013

YEAR: 2013     DOI: 10.1002/jgra.v118.910.1002/jgra.50472

dimensional analysis; low frequency variation; Pi Theorem; seasonal variation; semi-annual variation; thermospheric variability

Auroral Precipitation Model and its applications to ionospheric and magnetospheric studies

Based on statistical treatment of DMSP F6 and F7 spacecraft observations, an interactive Auroral Precipitation Model (APM) parameterized by magnetic activity has been created (available athttp://apm.pgia.ru/). For a given level of magnetic activity the model yields a global distribution of elect ...

Vorobjev, V.G.; Yagodkina, O.I.; Katkalov, Yu.V.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 09/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.05.007

AL and Dst indexes; Auroral Precipitation Model; Dayside aurorae; Magnetic storm

A comparative study of TEC response for the African equatorial and mid-latitudes during storm conditions

The solar wind effects on the Earth\textquoterights environment are studied for their basic scientific values and crucial practical impacts on technological systems. This paper reports results of Total Electron Content (TEC) changes during two successive ionospheric storms of 7\textendash12 November 2004 using GPS data derived from dual frequency receivers located at African equatorial and midlatitudes. In the geographic coordinate system, equatorial TEC variability is considered over Libreville (0.36\textdegreeN, 9.67\te ...

Habarulema, John; McKinnell, Lee-Anne; a, Dalia; Zhang, Yongliang; Seemala, Gopi; Ngwira, Chigomezyo; Chum, Jaroslav; Opperman, Ben;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 09/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.05.008

African equatorial and midlatitude TEC dynamics; Magnetic storms; TIDs

Ionospheric F-region response to geomagnetic disturbances

The F2-region reaction to geomagnetic storms usually called as an ionospheric storm is a rather complicated event. It consists of so called positive and negative phases, which have very complicated spatial and temporal behavior. The main morphological features of ionospheric storms and the main processes governing their behavior were understood at the end of the 1900s and described in a series of review papers. During the recent decade there were many publications dedicated to the problem of ionospheric storms. In this pa ...

Danilov, A.D.;

Published by: Advances in Space Research      Published on: 08/2013

YEAR: 2013     DOI: 10.1016/j.asr.2013.04.019

Geomagnetic disturbances; Ionosphere; Ionospheric storms

Are plasma bubbles a prerequisite for the formation of broad plasma depletions in the equatorial F region?

Formation of broad plasma depletions (BPDs) at night in the equatorial F region is understood in association with plasma bubbles. However, we report BPDs that do not show a connection with bubbles. The characteristics of BPDs are investigated using the observations of the Communication/Navigation Outage Forecasting System (C/NOFS) satellite on 31 December 2008, 28 July 2010, and 1 February 2011. On those days, BPDs are detected in the longitude regions where C/NOFS did not detect bubbles prior to the detection of ...

Kil, Hyosub; Lee, Woo;

Published by: Geophysical Research Letters      Published on: 07/2014

YEAR: 2013     DOI: 10.1002/grl.50693

bubbles; Equatorial ionosphere; irregularities

Is Space Weather Different Over Africa, and If So, Why? An AGU Chapman Conference Report

With the increasing reliance on technology, the impact of space weather on engineered systems will certainly increase unless suitable protective measures are taken. Understanding the physics behind space weather impacts and improving the forecasting are the major objectives of the space science community. It is well recognized that many space weather impacts, especially on communications systems, arise from structures in the ionosphere. The equatorial ionosphere, in particular, is one of the most complex and is host to nu ...

Yizengaw, Endawoke; Doherty, Patricia; Fuller-Rowell, Tim;

Published by: Space Weather      Published on: 07/2013

YEAR: 2013     DOI: 10.1002/swe.20063

atmosphere ionosphere interactions; ionospheric irregularities; space weather

Storm time spatial variations in TEC during moderate geomagnetic storms in extremely low solar activity conditions (2007\textendash2009) over Indian region

The total electron content (TEC) measurements from a network of GPS receivers were analyzed to investigate the storm time spatial response of ionosphere over the Indian longitude sector. The GPS receivers from the GPS Aided Geo Augmented Navigation (GAGAN) network which are uniquely located around the \~77\textdegreeE longitude are used in the present study so as to get the complete latitudinal coverage from the magnetic equator to low mid-latitude region. We have selected the most intense storms but of moderate intensity ...

Sunda, Surendra; Vyas, B.M.; Khekale, P.V.;

Published by: Advances in Space Research      Published on: 07/2013

YEAR: 2013     DOI: 10.1016/j.asr.2013.03.006

Electrodynamics; Equatorial and low-latitude; geomagnetic storm; Total electron content (TEC)

First observational evidence of the modulation of the threshold height h\textquoterightF c for the occurrence of equatorial spread F by neutral composition changes

[1]\ In the present study, the seasonal and solar activity variations of the threshold height for equatorial spread F occurrence irrespective of the polarity of the meridional winds during magnetically disturbed period are presented for the first time. The modulation of the seasonal pattern of the threshold height by the seasonal mean O/N2 values is also examined. The Ionosonde data of magnetic equatorial location Trivandrum (8.5\textdegreeN, 76.5\textdegreeE) and low latitude station SHAR (13.7\t ...

Haridas, M.; Manju, G.; Pant, Tarun;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50331

Equatorial Spread F; O/N2; solar activity; Threshold height

GNSS radio occultation (RO) derived electron density quality in high latitude and polar region: NCAR-TIEGCM simulation and real data evaluation

Global Navigation Satellite System (GNSS) based radio occultation (RO) technique has shown powerful ability in ionospheric electron density profiling in the past decade. The most frequently used Abel inversion method in electron density retrieval has some biases because of the used spherical symmetry assumption. Our previous series simulations and evaluations mainly concentrated in the middle and low latitude regions have shown some systematical bias especially in lower altitude of low latitude region. However, the RO der ...

Yue, Xinan; Schreiner, William; Kuo, Ying-Hwa; Wu, Qian; Deng, Yue; Wang, Wenbin;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1016/j.jastp.2013.03.009

Abel inversion; AURORA; COSMIC; Electron density; GNSS radio occultation; TIEGCM

The K p index and solar wind speed relationship: Insights for improving space weather forecasts

The Kp geomagnetic index forecasts are currently used to predict the aurora, MeV electron fluxes at geosynchronous, spacecraft anomalies and charging events, and times when accurate geological surveys can be performed. Many Kp forecasts rely on the upstream solar wind speed since the speed strongly correlates with the Kp index. However, the distribution of Kp and solar wind speed measurements is quite broad. To understand how common certain combinatio ...

Elliott, Heather; Jahn, Jörg-Micha; McComas, David;

Published by: Space Weather      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/swe.20053

Kp; solar wind speed; space weather forecasts

Long-term ionospheric cooling: Dependency on local time, season, solar activity, and geomagnetic activity

Ionospheric ion temperature Ti is an excellent approximation to neutral temperature Tn in the thermosphere, especially for altitudes below 300 km. This analysis of long-term Ti trends in the F region over different local times is based on a database of incoherent scatter radar (ISR) observations spanning more than three solar cycles during 1968\textendash2006 at Millstone Hill and represents an extended effort to a prior study focusing on noon-time only. This study provides important information for understanding the diff ...

Zhang, Shun-Rong; Holt, John;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50306

global change; incoherent scatter radar; ionospheric temperature; long-term trend; Millstone Hill

Nightside midlatitude ionospheric arcs: TIMED/GUVI observations

[1]\ Midlatitude arcs (MLA) are the phenomenon of the nightside enhancements of ionospheric electron density at 20\textdegree-45\textdegree magnetic latitudes in both hemispheres. We investigate the occurrence of MLA and its dependence on season using the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI) O I 135.6 nm intensity data between March 2008 and March 2012. The 135.6 nm emission is mainly caused by radiant recombination between O+ ions and electron ...

Zhang, Yongliang; Paxton, Larry; Kil, Hyosub;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50327

GUVI; Ionosphere; UV imager

Statistical analysis of an ionospheric parameter as a base for earthquake prediction

This paper is related to the use of ionospheric density variations to tentatively predict earthquakes. The results of this statistical analysis are presented as a function of various parameters. The ion density was recorded by the low-altitude satellite DEMETER during more than 6 years, and a search for anomalies was automatically conducted with the complete data set. In a second time, a software checked if each anomaly could correspond to an earthquake. The search was conducted at less than 1500 km from the anomaly posit ...

Li, Mei; Parrot, Michel;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50313

earthquake; Ionosphere

Thermospheric tidal effects on the ionospheric midlatitude summer nighttime anomaly using SAMI3 and TIEGCM

This paper is the first study to employ a three-dimensional physics-based ionosphere model, SAMI3, coupled with the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) and Global Scale Wave Model to simulate the mesospheric and lower thermospheric tidal effects on the development of midlatitude summer nighttime anomaly (MSNA). Using this coupled model, the diurnal variation of MSNA electron densities at 300 km altitude is simulated on both June solstice (day ...

Chen, C.; Lin, C.; Chang, L.; Huba, J.; Lin, J.; Saito, A.; Liu, J;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/jgra.50340

MSNA; SAMI3; tidal effect; TIEGCM

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-Ionos ...

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

Ground-based GPS observation of SED-associated irregularities over CONUS

\ It has been known that steep total electron content (TEC) gradients observed at the boundary between the storm-enhanced plasma density (SED) and the low TEC region at subauroral and midlatitude regions are associated with ionospheric irregularities that impact communication and navigation systems. However, the relationship between the SED-associated irregularities and TEC gradients is still not well understood, partly because of the difficulties of resolving small-scale TEC gradients from sparsely distributed TEC o ...

Sun, Yang-Yi; Matsuo, Tomoko; Araujo-Pradere, Eduardo; Liu, Jann-Yenq;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2013

YEAR: 2013     DOI: 10.1029/2012JA018103

data assimilation; irregularity; nonstationary covariance; SED; TEC gradient

Ionospheric response to a geomagnetic storm during November 8\textendash10, 2004

This paper investigates the response of the equatorial, and near equatorial, ionosphere to geomagnetic disturbances during the period November 8-10, 2004. Ionosonde data from Trivandrum (8.5\textdegreeN 77\textdegreeE and dip 0.5\textdegreeN) and SHAR (13.5\textdegreeN, 80.2\textdegreeE, dip \~5.5\textdegreeN), magnetic field data from Tirunelveli (8.7\textdegreeN, 76.9\textdegreeE, dip latitude 0.5\textdegreeS) and Alibag (18.64\textdegreeN, 72.87\textdegreeE), and GUVI O/N2 data in the Indian longitude sector ...

Simi, K.; Manju, G.; Haridas, M.; Nayar, S.; Pant, Tarun; Alex, S.;

Published by: Earth, Planets and Space      Published on: 05/2013

YEAR: 2013     DOI: 10.5047/eps.2012.09.005

Equatorial Electrojet; Equatorial ionization anomaly; geomagnetic storm; O/N2 ratio

Large-scale ionospheric disturbances due to the dissipation of convectively-generated gravity waves over Brazil

In a companion paper, we show that large-scale secondary gravity waves and circulation cells are created by the body forces generated by the dissipation of convectively generated gravity waves over Brazil on 01 October 2005. In this paper, we show that these fluid perturbations cause large-scale perturbations of the plasma drift and plasma density in the ionosphere by changing the wind dynamo and transport. These fluid perturbations modify both the amplitude and direction of the plasma drifts. Near the geomagnetic equator ...

Liu, H.-L.; Vadas, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2013

YEAR: 2013     DOI: 10.1002/jgra.50244

atmosphere coupling; atmosphere gravity wave; ionospheric variability; tropospheric convection

Physical mechanisms of the ionospheric storms at equatorial and higher latitudes during the recovery phase of geomagnetic storms

The paper studies the physical mechanisms of the ionospheric storms at equatorial and higher latitudes, which are generally opposite both during the main phase (MP) and recovery phase (RP) of geomagnetic storms. The mechanisms are based on the natural tendency of physical systems to occupy minimum energy state which is most stable. The paper first illustrates the recent developments in the understanding of the mechanisms during daytime MPs when generally negative ionospheric storms (in Nmax and TEC) develop at equatorial ...

Balan, N.; Otsuka, Y.; Nishioka, M.; Liu, J; Bailey, G.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2013

YEAR: 2013     DOI: 10.1002/jgra.50275

Geomagnetic storms; Ionospheric storms; physical mechanisms



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