Bibliography

Connection between high-latitude arcs and the low-latitude boundary layer during periods of northward IMF

Maggiolo, Romain; Fontaine, Dominique; Hosokawa, Keisuke; Maes, Lukas; Zhang, Yongliang; Fear, Robert; Cumnock, Judy; Kozlovsky, Alexander; Kullen, Anita; Milan, Steve; , others;

Published by:       Published on:

YEAR: 2014     DOI:

A comprehensive empirical model of the ionospheric conductivity derived from SSUSI/GUVI, SuperMAG and SuperDARN data.

Gjerloev, Jesper; Schaefer, Robert; Paxton, Larry; Zhang, Yongliang;

Published by:       Published on:

YEAR: 2014     DOI:

Ionospheric Data Assimilation from a Data Provider's Perspective

Schaefer, Robert; Paxton, Larry; Bust, G; Zhang, Yongliang; Romeo, Giuseppe; Comberiate, Joseph; Gelinas, Lynette;

Published by:       Published on:

YEAR: 2014     DOI:

EMIC Wave Induced Radiation Belt Losses and Proton Aurora

Erlandson, Robert; Paxton, Larry; Zhang, Yongliang; Schaefer, Robert;

Published by:       Published on:

YEAR: 2014     DOI:

On transpolar arc formation correlated with solar wind entry at high latitude magnetosphere

Mailyan, Bagrat; Shi, Quanqi; Maggiolo, Romain; Zong, Qiugang; Fu, SuiYan; Zhang, Yongliang; Yao, Zhonghua; Sun, W;

Published by:       Published on:

YEAR: 2014     DOI:

Specification of Auroral Ionospheric Conductances Using SSUSI and GUVI UV Imagery

Paxton, Larry; Zhang, Yongliang; Schaefer, Robert; Weiss, Michele; Miller, Ethan;

Published by:       Published on:

YEAR: 2014     DOI:

Thermospheric Composition Variability and Its Coupling to the Ionosphere I

Zhang, Yongliang; Paxton, Larry; Fuller-Rowell, Timothy; Knipp, Delores;

Published by:       Published on:

YEAR: 2014     DOI:

OVATION Prime-2013: Solar Wind Driven Precipitation Model Extended to Higher Geomagnetic Activity Levels

Newell, Patrick; Liou, Kan; Zhang, Yongliang; Sotirelis, Thomas; Paxton, Larry; Mitchell, Elizabeth;

Published by:       Published on:

YEAR: 2014     DOI:

The zonal motion of equatorial plasma bubbles relative to the background ionosphere

Kil, Hyosub; Lee, Woo; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry; Milla, Marco;

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

YEAR: 2014     DOI:

The zonal motion of equatorial plasma bubbles relative to the background ionosphere

Kil, Hyosub; Lee, Woo; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry; Milla, Marco;

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

YEAR: 2014     DOI:

Ground and satellite observations of multiple sun-aligned auroral arcs on the duskside

Hosokawa, Keisuke; Maggiolo, Romain; Zhang, Yongliang; Fear, Robert; Fontaine, Dominique; Cumnock, Judy; Kullen, Anita; Milan, Stephen; Kozlovsky, Alexander; Echim, Marius; , others;

Published by:       Published on:

YEAR: 2014     DOI:

Storm-Time Behaviors of the Thermospheric O/N2 and NO Variations

Zhang, Yongliang; Paxton, Larry; Morrison, Daniel; Kil, Hyosub; Marsh, Daniel;

Published by:       Published on:

YEAR: 2014     DOI:

Updated Global Data from the Guvi Instrument: New Products, Updated Calibration, and a New Web Interface

Schaefer, Robert; Paxton, Larry; Romeo, Giuseppe; Wolven, Brian; Zhang, Yongliang; Comberiate, Joseph;

Published by:       Published on:

YEAR: 2014     DOI:

Multi-instrument observations of multiple auroral arcs in the duskside polar cap region

Hosokawa, Keisuke; Maggiolo, Romain; Zhang, Yongliang; Fear, Rob; Fontaine, Dominique; Cumnock, Judy; Kullen, Anita; Milan, Steve; Kozlovsky, Alexander; Echim, Marius;

Published by:       Published on:

YEAR: 2014     DOI:

Equatorial broad plasma depletions associated with the enhanced fountain effect

Lee, Woo; Kil, Hyosub; Kwak, Young-Sil; Paxton, Larry; Zhang, Yongliang; Galkin, Ivan; Batista, Inez;

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

YEAR: 2014     DOI:

Near real-time global auroral observations and their application to IRI

Zhang, Yongliang; Paxton, Larry; Bilitza, Dieter;

Published by: 40th COSPAR Scientific Assembly      Published on:

YEAR: 2014     DOI:

Forcing of the Coupled Ionosphere-Thermosphere (IT) System During Magnetic Storms

Huang, Cheryl; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric; Hairston, Marc; Coley, Robin; Doornbos, Eelco; Zhang, Yongliang;

Published by:       Published on:

YEAR: 2014     DOI:

The International Reference Ionosphere 2012--a model of international collaboration

Bilitza, Dieter; Altadill, David; Zhang, Yongliang; Mertens, Chris; Truhlik, Vladimir; Richards, Phil; McKinnell, Lee-Anne; Reinisch, Bodo;

Published by: Journal of Space Weather and Space Climate      Published on:

YEAR: 2014     DOI:

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\ ratio contamination by the ionosphere using the GUVI observations and model ionosphere acquired from 31 August to 2 September 2002. During this period, the local time of the GUVI observation was near 1500 and the average\ Kp\ index was 2\textdegree. The 135.6 nm emission originated from the ionosphere is estimated using the electron density profiles provided by the Utah State University-Global Assimilation of Ionospheric Measurements model. Our results show that the 135.6 nm emission originated from the equatorial ionization anomaly (EIA) contributes 5 ~ 10\% to the total 135.6 nm intensity and O/N₂\ ratio. The EIA feature and longitudinal wave patterns in the GUVI 135.6 nm intensity maps are identified above an altitude of 300 km and show a good agreement with those in the\ F\ region plasma density. However, the EIA feature and longitudinal wave patterns do not appear in the GUVI 135.6 nm intensity maps below an altitude of 300 km and in the GUVI N₂\ Lyman-Birge-Hopfield band intensity maps in any altitude. These observations indicate that the longitudinal wave patterns in the GUVI O/N₂\ ratio represent the ionospheric phenomenon.

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 emission arises from two sources: photoelectron impact excitation of neutral atomic oxygen and the radiative recombination of O⁺ with electrons. We estimate the O/N₂ ratio disturbance associated with the O⁺ density enhancement during geomagnetic storms through the case study of the storms on 20 November 2003 and 8 November 2004. The OI 135.6 nm emission enhancement originating from the ionosphere is derived using the Utah State University Global Assimilation of Ionospheric Measurements model ionosphere. Our results show that the O/N₂ ratio increase from the equator to middle latitudes during the storm periods is primarily associated with thermospheric neutral composition disturbances. However, the contribution of the OI 135.6 nm emission originating from the ionosphere to the storm time O/N₂ ratio increase is substantial in the northern low-middle latitude regions where severe plasma density enhancements occur during the main phase of the storms. Therefore, the ionospheric contribution should be considered for an accurate assessment of the storm time O/N₂ ratio increase at low-middle latitudes during these large storm events.

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

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 the second most significant component). We find a high degree of correlation between spatial variations in the second EOF mode and vertical drifts driven by thermospheric zonal winds, along with well-organized temporal variation. Results strongly suggest a causative mechanism involving varying declination with longitude along with varying zonal wind climatology with local time, season, and solar cycle. This study highlights the efficiency and key role played by the geomagnetic field effect in influencing mesoscale ionospheric structures over a broad midlatitude range.

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

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\textdegreeE), Gabon and Mbarara (0.60\textdegreeS, 30.74\textdegreeE), Uganda. TEC over midlatitude stations Sutherland (32.38\textdegreeS, 20.81\textdegreeE) and Springbok (29.67\textdegreeS, 17.88\textdegreeE), South Africa are analysed. The analysis of the storm time ionospheric variability over South Africa was undertaken by comparing the critical frequency of the F2 layer (foF2) and the peak height of the F2 layer (hmF2) values obtained from Grahamstown (33.30\textdegreeS, 26.53\textdegreeE) and Madimbo (22.4\textdegreeS, 30.9\textdegreeE) ionosonde measurements. During the analysed storm period it is observed that GPS TEC for midlatitudes was depleted significantly with a corresponding depletion in foF2, due to the reduction in GUVI O/N₂ ratio as observed from its global maps. Over the equatorial latitudes, positive storm effects are more dominant especially during the storm main phase. Negative storm effects are observed over both mid and equatorial latitudes during the recovery phase. A shift in equatorial TEC enhancement (from one GPS station to another) is observed during magnetic storms and has been partially attributed to passage of Travelling Ionospheric Disturbances (TIDs). Magnetometer data over the International Real-time Magnetic Observatory Network (intermagnet) station, Addis Ababa, AAE (9.03\textdegreeN, 38.77\textdegreeE) has been used to help with the explanation of possible causes of equatorial ionospheric TEC dynamics during the analysed magnetic storm period.

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

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 difference between the ISR and other results. A gross average of the Ti trend at heights of Ti \~ Tn (200\textendash350 km) is \~ -4 K/decade, a cooling trend close to the Tn estimation based on the satellite neutral density data. However, there exists considerable variability in the cooling: it is strong during the day and very weak during the night with a large apparent warming at low altitudes (200\textendash350 km); it is strong at solar minimum for both daytime and nighttime. The strongest cooling for altitudes below 375 km occurs around 90\textendash120 solar flux units of the 10.7 cm solar flux, not at the lowest solar flux. There appears more cooling toward high magnetic activity, but this dependency is very weak. No consistent and substantial seasonal dependency across different heights was found. We speculate that a fraction of the observed cooling trend may be contributed by a gradual shifting away from the sub-auroral region at Millstone Hill, as part of the secular change in the Earth\textquoterights magnetic field. In this 39 year long series of data record, two anomalous Ti drops were noticed, and we speculate on their connection to volcano eruptions in 1982 and 1991.

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 electrons in the nightside ionosphere. The GUVI data show that the MLA occurred in all seasons under geomagnetically quiet condition (mean Kp ~ 1.0) and during periods of low solar activity. Hemispheric symmetric MLA were observed during equinox. During solstice, the MLA were seen only in the winter hemisphere. The MLA were more frequently observed at local times between ~21:00 and 02:00 on nightside. They were rarely observed at local times between 03:00 and sun rise. The MLA were observed with an occurrence frequency of ~75\% of the time. Coincident GPS total electron current data confirm that the MLA were due to enhanced ionospheric electron density. GUVI 135.6 nm limb data further show that the altitude of the MLA is higher than that of the equatorial arcs created by the equatorial ionization anomaly or fountain effect. The appearance of the MLA at higher altitude than the equatorial arcs supports the idea that the creation of the MLA is associated with the uplift of the ionosphere by the equatorward neutral wind.

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 comparison of isolated and non-isolated auroral substorms

The present study compares isolated and non-isolated substorms in terms of their global morphology and energy deposition. The analysis is based on a list of geomagnetic substorm onsets identified with magnetometer data from SuperMAG and published previously by Newell and Gjerlove (2011a). Isolated substorms are defined as those with separation of two consecutive onsets no less than 3 h. The auroral data are obtained from the global ultraviolet imager (GUVI) on board the TIMED satellite and are rebinned into typical magnetic latitude-magnetic local time maps. The auroral maps are then averaged in 1 min intervals to show the dynamic change of the aurora. The three phases of the substorm are clearly demonstrated in both isolated and non-isolated substorms. However, there are noticeable differences between the two types of substorms: (1) While the nighttime auroral power for both types of substorms slightly increases in the growth phase, isolated (non-isolated) substorms are associated with smaller (greater) nighttime auroral power. (2) In the expansion phase, isolated substorms are associated with greater and more explosive energy release than non-isolated substorms. (3) The time for the recovery phase is ~2 times longer for isolated than for non-isolated substorms. (4) The winter-to-summer auroral power ratio is approximately constant throughout the three substorm phases and the ratio is larger for isolated (~30\%) than that for non-isolated (~10\%) substorms. It is also found that the polar cap area increases during the growth phase until ~10 min prior to the magnetic substorm onset and decreases rapidly thereafter. The decrease is found to result from the closure of the nightside polar cap associated with substorm expansion. It is found that the observed differences between the two types of substorms simply reflect the differences in the solar wind and EUV drivers. Thus, we conclude that there is no intrinsic difference between isolated and non-isolated substorms in terms of auroral energy release and subsequent auroral power decay.

Liou, Kan; Newell, Patrick; Zhang, Yong-Liang; Paxton, Larry;

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

YEAR: 2013     DOI: 10.1002/jgra.50218

auroral power; auroral substorm; GUVI; SuperMAG; TIMED

Multi-Periodic Auroral and Thermospheric Variations in 2006

Zhang, Yongliang; Paxton, L.; Kil, Hyosub;

Published by: Terrestrial, Atmospheric and Oceanic Sciences      Published on: 04/2013

YEAR: 2013     DOI: 10.3319/TAO.2012.09.20.01(SEC)

Empirical relationship between electron precipitation and far-ultraviolet auroral emissions from DMSP observations

Auroral emissions observed in the far-ultraviolet wavelength range are compared with measurements of the coincident precipitating electrons and ions that produce the emissions in a large-scale correlative study. The auroral emissions and particle precipitation are observed with the Special Sensor Ultraviolet Spectrographic Imager and SSJ5 detectors, respectively, both onboard the DMSP F16 satellite. Coincident observations along the same magnetic field line in the Northern Hemisphere are assembled from two consecutive winters (during 2005\textendash2007). A numerical fit to 27,922 coincident observations provides an empirical relationship between the electron energy flux and the intensity of Lyman-Birge-Hopfield long emissions, J_Ee = 4.90 .10⁸ (eV s^\textendash1 sr^\textendash1 cm^\textendash2)/R I_LBHL (valid in the absence of significant ion fluxes: J_Ee \> 10 J_Eion). A fit to 1308 coincident observations provides the relationship between the average electron energy and the Lyman-Birge-Hopfield short to Lyman-Birge-Hopfield long emission ratio, \<E_e \> = 19.6 keV exp(\textendash2.34 I_LBHS / I_LBHL) (valid from 3 to 19.6 keV). These resulting empirical relationships permit the energy flux and average energy of precipitating electrons to be inferred from far-ultraviolet imagery, in the absence of significant ion precipitation.

Sotirelis, Thomas; Korth, Haje; Hsieh, Syau-Yun; Zhang, Yongliang; Morrison, Daniel; Paxton, Larry;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2013

YEAR: 2013     DOI: 10.1002/jgra.50157

DMSP; electron aurora; electron precipitation; FUV Aurora

Multi-Instrument Observations at High Latitudes

Miller, E; Paxton, L; Schaefer, RK; Weiss, M; Wolven, BC; Zhang, Y;

Published by:       Published on:

YEAR: 2013     DOI:

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:

YEAR: 2013     DOI:

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:

Ring current and polar rain auroras

Zhang, Y; Paxton, L; Kil, H;

Published by:       Published on:

YEAR: 2013     DOI:

The Study of the origin of broad plasma depletions in the equatorial F region

Oh, S; Lee, W; Kil, H; Kwak, Y; Paxton, L; Zhang, Y;

Published by:       Published on:

YEAR: 2013     DOI:

Drivers of the hemispheric asymmetry in the low-latitude electron density distribution

Kil, H; Kwak, Y; Lee, W; Paxton, L; Zhang, Y;

Published by:       Published on:

YEAR: 2013     DOI:

Three-Dimensional, Multi-scale, and Multi-variance Dispersivity Upscaling for Hierarchical Sedimentary Deposit using Parallel Computing

Zhang, Mingkan; Zhang, Ye; Lichtner, PC;

Published by:       Published on:

YEAR: 2013     DOI:

Three-Dimensional, Multi-scale, and Multi-variance Dispersivity Upscaling for Hierarchical Sedimentary Deposit using Parallel Computing

Zhang, Mingkan; Zhang, Ye; Lichtner, PC;

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:

SSUSI: A Newly Available Resource for the Upper Atmosphere Community to Study the Global Response of the Coupled Ionosphere Thermosphere System

Paxton, L; Schaefer, RK; Weiss, M; Wolven, BC; Zhang, Y; Miller, E; Bust, GS; Romeo, G;

Published by:       Published on:

YEAR: 2013     DOI:

An interhemispheric comparison of GPS phase scintillation with auroral emission observed at the South Pole and from the DMSP satellite

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:

YEAR: 2013     DOI:

Behaviors of the ionospheric and thermospheric disturbances during geomagnetic storms

Kil, H; Lee, W; Zhang, Y; Paxton, LJ;

Published by:       Published on:

YEAR: 2013     DOI:

SSUSI Aurora Forecast Model

A new capability has been developed at JHU/APL for forecasting the global aurora quantities based on the DMSP SSUSI data and the TIMED/GUVI Global Aurora Model. The SSUSI Aurora Forecast Model predicts the electron energy flux, mean energy, and equatorward boundary in the auroral oval for up to 1 day or 15 DMSP orbits in advance. In our presentation, we will demonstrate this newly implemented capability and its results. The future improvement plan will be discussed too.

Hsieh, S.~W.; Zhang, Y.; Schaefer, R.~K.; Romeo, G.; Paxton, L.;

Published by: AGU Fall Meeting Abstracts      Published on:

YEAR: 2013     DOI:

Auroral phenomena; forecasting; Ionosphere/magnetosphere interactions; Modeling and forecasting

The effect of the 135.6 nm emission originated from the ionosphere on the TIMED/GUVI O/N2 ratio

Kil, H; Lee, WK; Shim, J; Paxton, LJ; Zhang, Y;

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

YEAR: 2013     DOI:

Large-scale structures in the Polar Rain

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

Published by: Geophysical Research Letters      Published on:

YEAR: 2013     DOI:

The effect of geomagnetic-storm-induced enhancements to ionospheric emissions on the interpretation of the TIMED/GUVI O/N2 ratio

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

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

YEAR: 2013     DOI:

An interhemispheric comparison of GPS phase scintillation with auroral emission observed at South Pole and from DMSP satellite

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:

YEAR: 2013     DOI:

A simulation study for the couplings between DE3 tide and longitudinal WN4 structure in the thermosphere and ionosphere

Wan, W.; Ren, Z.; Ding, F.; Xiong, J.; Liu, L.; Ning, B.; Zhao, B.; Li, G.; Zhang, M.-L.;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on: Jan-12-2012

YEAR: 2012     DOI: 10.1016/j.jastp.2012.04.011

Dayside and nightside segments of a polar arc: The particle characteristics

Park, J.; Min, K.; Parks, G.; Zhang, Y.; Lee, J.-J.; Baker, J.; Kim, H.; Hwang, J.; Yumoto, K.; Uozumi, T.; Lee, C.;

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

YEAR: 2012     DOI: 10.1029/2011JA017323

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

Polar cap arcs from the magnetosphere to the ionosphere: kinetic modelling and observations by Cluster and TIMED

Maggiolo, R.; Echim, M.; Wedlund, Simon; Zhang, Y.; Fontaine, D.; Lointier, G.; Trotignon, J.-G.;

Published by: Annales Geophysicae      Published on: Jan-01-2012

YEAR: 2012     DOI: 10.5194/angeo-30-283-2012

Reply to comment by D.J. Strickland et al. on \textquotedblleftLong-term variation in the thermosphere: TIMED/GUVI observations\textquotedblright

Zhang, Yongliang; Paxton, L.;

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

YEAR: 2012     DOI: 10.1029/2012JA017594

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