Bibliography

Universal time variations of the auroral hemispheric power and their interhemispheric asymmetry from TIMED/GUVI observations

This paper quantitatively analyzes the auroral hemispheric power (HP) and its interhemispheric asymmetry as a function of universal time (UT) for geomagnetically quiet conditions (Kp 1\textendash3) from Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI) imaging observations. The HP variation with UT can be approximately characterized as two cases: One is for similar HP variations in the equinoxes in the Northern Hemisphere and for the June solstices of both hemispheres, and the other is for similar HP patterns in the equinoxes in the Southern Hemisphere and for the December solstices of both hemispheres. In the equinoxes, the HP variations are interhemispherically asymmetric due to different occurrence time of the HP peak. In the solstices, the HP is generally interhemispherically symmetric in its diurnal variations, but there is interhemispheric asymmetry in the magnitudes of the maximum HP. For geomagnetically quiet conditions (Kp = 2), in the equinoxes relative interhemispheric differences are typically between 0 and 20\%, with respect to the averaged HP from the two hemispheres, while during the solstices, the maximum relative interhemispheric asymmetry can be as large as 30\% in December, but it is only ~15\% in June. These two cases are mainly associated with variations of auroral precipitation power in the night side sector (21:00\textendash03:00 magnetic local time/MLT), which are primarily controlled by solar illumination conditions in both hemispheres and are also attributed to the difference in the geographical area of the auroral oval in the two hemispheres. Furthermore, the general interhemispheric symmetry of the HP variations in solstices suggests that auroral acceleration is not only controlled locally by solar illumination conditions, which has been well known previously, but also might be affected by processes in the precipitation source region.

Luan, Xiaoli; Wang, Wenbin; Burns, Alan; Dou, Xiankang;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2016

YEAR: 2016     DOI: 10.1002/2016JA022730

Middle-and low-latitude ionosphere response to 2015 St. Patrick's Day geomagnetic storm

Nava, B; iguez-Zuluaga, Rodr\; Alazo-Cuartas, K; Kashcheyev, A; e, Migoya-Oru\; Radicella, SM; Amory-Mazaudier, Christine; Fleury, Rolland;

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

YEAR: 2016     DOI: 10.1002/2015JA022299

Ionospheric data assimilation and forecasting during storms

Chartier, Alex; Matsuo, Tomoko; Anderson, Jeffrey; Collins, Nancy; Hoar, Timothy; Lu, Gang; Mitchell, Cathryn; Coster, Anthea; Paxton, Larry; Bust, Gary;

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

YEAR: 2016     DOI:

Characteristics of ionospheric north-south asymmetry and their relationship with irregularity

Using the empirical ionospheric model, the flux-tube integrated electron density and the ratio between the F-region Pedersen conductivity and the total E- and F-region Pedersen conductivity are calculated to investigate the characteristics of the ionospheric asymmetry after sunset during a solar cycle. Furthermore, two indices representing the asymmetric strength of the parameters respectively are defined to study its relationship with the occurrences of the irregularities during different seasons and with different solar activities. The results indicate that the electron density and the Pedersen conductivity ratio show north-south remarkable hemispheric asymmetry at different solar energy levels. The asymmetric strengths represent the dependence on seasons and solar activities, and their variation depending on seasons and solar activities show a negative correlation with the occurrences of the equatorial irregularities and also have a negative relation with the linear growth rate of the generalized Rayleigh-Taylor instability.

Luo, Weihua; Zhu, Zhengping; Lan, Jiaping; Li, Xuejing;

Published by: Wuhan University Journal of Natural Sciences      Published on: 06/2015

YEAR: 2015     DOI: 10.1007/s11859-015-1088-7

asymmetry; Electron density; Ionosphere; irregularity; Pedersen conductivity

Longitudinal variations of the nighttime E layer electron density in the auroral zone

Longitudinal variations of the nighttime E layer electron density (21:00\textendash03:00 magnetic local time) in the auroral zone are investigated, and their sources are discussed in terms of auroral precipitation and solar radiation. The electron density data used in this study are retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation observations during 2006\textendash2009 under quiet geomagnetic activity (Kp <= 3) and solar minimum conditions. The main conclusions of this study are as follows: (1) the nighttime E layer electron density had pronounced longitudinal variations in the auroral zone. These variations depended on season and had large hemispheric asymmetry for all seasons. In winter, relatively larger electron density was located in 120\textendash310\textdegree magnetic longitude (MLON) in the northern hemisphere and in 170\textendash360\textdegree MLON in the southern hemisphere, and greater maximum density occurred in the northern hemisphere than in the southern one. In summer and equinox, the longitudinal asymmetry was greater in the southern hemisphere. (2) The peaks of the E layer electron density along latitude generally occurred between 65\textdegree and 70\textdegree magnetic latitude in the auroral zone in all seasons for both hemispheres except for the sunlit sector of the southern summer. (3) The greater electron density in local winter in the auroral zone was generally associated with the more intense auroral precipitation intensity at roughly the same longitude, whereas the longitudinal patterns of the electron density were under the combined impact of both auroral precipitation and solar radiation in the local summer and equinoxes.

Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan;

Published by: Journal of Geophysical Research: Space Physics      Published on: 01/2015

YEAR: 2015     DOI: 10.1002/2014JA020610

auroral E layer; hemispheric asymmetry; longitudinal variations; Seasonal variations

Longitudinal variations of the nighttime E layer electron density in the auroral zone

Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan;

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

YEAR: 2015     DOI:

Solar Activity Dependence of Night Side Aurora in Winter/Dark Conditions

Luan, Xiaoli; Zhou, Su; Dou, Xiankang;

Published by:       Published on:

YEAR: 2015     DOI:

Simulations of the equatorial thermosphere anomaly: Geomagnetic activity modulation

The modulation of geomagnetic activity on the equatorial thermosphere anomaly (ETA) in thermospheric temperature under the high solar activity condition is investigated using the Thermosphere Ionosphere Electrodynamics General Circulation Model simulations. The model simulations during the geomagnetically disturbed interval, when the north-south component of the interplanetary magnetic field (B_z) oscillates between southward and northward directions, are analyzed and also compared with those under the quiet time condition. Our results show that ionospheric electron densities increase greatly in the equatorial ionization anomaly (EIA) crest region and decrease around the magnetic equator during the storm time, resulting from the enhanced eastward electric fields. The impact of both the direct heat deposition at high latitudes and the modulation of the storm time enhanced EIA crests on the ETA are subsequently studied. The increased plasma densities over the EIA crest region enhance the field-aligned ion drag that accelerates the poleward meridional winds and consequently their associated adiabatic cooling effect. This process alone produces a deeper temperature trough over the magnetic equator as a result of the enhanced divergence of meridional winds. Moreover, the enhanced plasma-neutral collisional heating at higher latitudes associated with the ionospheric positive storm effect causes a weak increase of the ETA crests. On the other hand, strong changes of the neutral temperature are mainly confined to higher latitudes. Nevertheless, the changes of the ETA purely due to the increased plasma density are overwhelmed by those associated with the storm time heat deposition, which is the major cause of an overall elevated temperature in both the ETA crests and trough during the geomagnetically active period. Associated with the enhanced neutral temperature at high latitudes due to the heat deposition, the ETA crest-trough differences become larger under the minor geomagnetic activity condition than under the quiet time condition. However, when geomagnetic activity is further elevated, the ETA crests tend to be masked by high temperatures at middle and high latitudes.

Lei, Jiuhou; Wang, Wenbin; Thayer, Jeffrey; Luan, Xiaoli; Dou, Xiankang; Burns, Alan; Solomon, Stanley;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2014

YEAR: 2014     DOI: 10.1002/2014JA020152

equatorial thermosphere anomaly; geomagnetic activity; ion-neutral coupling; positive ionospheric storm

Solar filament impact on 21 January 2005: Geospace consequences

On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere\textemdashan unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks\textemdashhigh enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1\textendash2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material.

Kozyra, J.; Liemohn, M.; Cattell, C.; De Zeeuw, D.; Escoubet, C.; Evans, D.; Fang, X.; Fok, M.-C.; Frey, H.; Gonzalez, W.; Hairston, M.; Heelis, R.; Lu, G.; Manchester, W.; Mende, S.; Paxton, L.; Rastaetter, L.; Ridley, A.; Sandanger, M.; Soraas, F.; Sotirelis, T.; Thomsen, M.; Tsurutani, B.; Verkhoglyadova, O.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2014

YEAR: 2014     DOI: 10.1002/2013JA019748

cold dense plasma sheet; Equatorial anomaly; magnetotail; precipitation; prompt penetration electric field; solar filament

Auroral all-sky camera calibration

A two-step procedure to calibrate the spectral sensitivity to visible light of auroral all-sky cameras is outlined. Center pixel response is obtained by the use of a Lambertian surface and a

Sigernes, Fred; Holmen, SE; Biles, D; Bj\orklund, H; Chen, X; Dyrland, M; Lorentzen, DA; Baddeley, L; Trondsen, T; Brändström, U; , others;

Published by: Geoscientific Instrumentation, Methods and Data Systems      Published on:

YEAR: 2014     DOI: 10.5194/gi-3-241-2014

Longitudinal and Hemispheric Variations of Nighttime E-Layer Electron Density in the Auroral Zone

Luan, Xiaoli; Wang, Wenbin; Dou, Xiankang; Burns, Alan; Yue, Xinan;

Published by:       Published on:

YEAR: 2014     DOI:

Next Generation Instrumentation in Solar and Space Physics: Critical Measurements from Low-Cost Missions/Platforms I

DeLuca, Edward; Paxton, Larry; Schwadron, Nathan; Millan, Robyn;

Published by:       Published on:

YEAR: 2014     DOI:

The NCAR TIE-GCM: A community model of the coupled thermosphere/ionosphere system

Qian, Liying; Burns, Alan; Emery, Barbara; Foster, Benjamin; Lu, Gang; Maute, Astrid; Richmond, Arthur; Roble, Raymond; Solomon, Stanley; Wang, Wenbin;

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

YEAR: 2014     DOI:

Improving Discoverability of Geophysical Data using Location Based Services

Morrison, Daniel; Barnes, Robin; Potter, Matthew; Nylund, Stuart; Patrone, Dennis; Weiss, Michele; Talaat, Elsayed; Sarris, Theodore; Smith, Daniel;

Published by:       Published on:

YEAR: 2014     DOI:

Annual asymmetry in thermospheric density: Observations and simulations

[1]\ In this paper, the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) observations during 2002\textendash2010 are utilized to study the variation of the annual asymmetry in thermospheric density at 400 km under low solar activity condition (F10.7 = 80) based on the method of empirical orthogonal functions (EOFs). The derived asymmetry index (AI) in thermospheric density from the EOF analysis shows a strong latitudinal variation at night but varies a little with latitudes in daytime. Moreover, it exhibits a terdiurnal tidal signature at low to middle latitudes. The global mean value of the AI is 0.191, indicating that a 47\% difference in thermosphere between the December and June solstices in the global average. In addition, the NCAR Thermosphere-Ionosphere Electrodynamics Global Circulation Model (TIEGCM) is used to explore the possible mechanisms responsible for the observed annual asymmetry in thermospheric density. It is found that the standard simulations give a lower AI and also a weaker day-to-night difference. The simulated AI shows a semidiurnal pattern in the equatorial and low-latitude regions in contrast with the terdiurnal tide signature seen in the observed AI. The daily mean AI obtained from the simulation is 0.125, corresponding to a 29\% December-to-June difference in thermospheric density at 400 km. Further sensitivity simulations demonstrated that the effect of the varying Sun-Earth distance between the December and June solstices is the main process responsible for the annual asymmetry in thermospheric density, while the magnetic field configuration and tides from the lower atmosphere contribute to the temporal and spatial variations of the AI. Specifically, the simulations show that the Sun-Earth distance effect explains 93\% of the difference in thermospheric density between December and June, which is mainly associated with the corresponding changes in neutral temperature. However, our calculation from the density observations reveals that the varying Sun-Earth distance effect only accounts for ~67\% of the December-to-June difference in thermosphere density, indicating that the TIEGCM might significantly underestimate the forcing originating from the lower atmosphere.

Lei, Jiuhou; Dou, Xiankang; Burns, Alan; Wang, Wenbin; Luan, Xiaoli; Zeng, Zhen; Xu, JiYao;

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

YEAR: 2013     DOI: 10.1002/jgra.50253

Annual asymmetry; Empirical orthogonal functions; Sun-Earth distance; Upper thermosphere

Geomagnetic and auroral activity driven by corotating interaction regions during the declining phase of Solar Cycle 23

A superposed epoch analysis is performed to investigate the relative impact of the solar wind/interplanetary magnetic field (IMF) on geomagnetic activity, auroral hemispheric power, and auroral morphology during corotating interaction regions (CIRs) events between 2002 and 2007, when auroral images from Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Global Ultraviolet Imager were available. Four categories of CIRs have been compared. These were classified by the averaged IMF Bz and the time of maximum solar wind dynamic pressure around the CIR stream interface or onset time. It is found that during CIR events: (1) The peaks of auroral power and Kp were largely associated with dominant southward Bz, whereas auroral activity also became stronger with increases of solar wind speed, density, and dynamic pressure. (2) The percentage and absolute increases of auroral hemispheric power with solar wind speed were much greater under dominantly northward Bz conditions than under dominantly southward Bz conditions. (3) The enhancement of the auroral power and Kp with increasing solar wind speed followed the same pattern, for both dominantly southward and northward Bz conditions, regardless of the behavior of solar wind density and dynamic pressure. These results suggest that, during CIR events, southward Bz played the most critical role in determining geomagnetic and auroral activity, whereas solar wind speed was the next most important contributor. The solar wind dynamic pressure was the less important factor, as compared with Bz and solar wind speed. Relatively strong auroral precipitation energy flux (\> ~3 mW/m²) occurred in a wider auroral oval region after the stream interface than before it for both dominantly northward and southward Bz conditions. These conditions enhanced the auroral hemispheric power after the stream interface. Intense auroral precipitation (\> ~4 mW/m²) generally occurred widely at night under dominantly southward Bz conditions, but the location of this precipitation in the auroral oval was different when it was associated with different solar wind density and speed conditions.

Luan, Xiaoli; Wang, Wenbin; Lei, Jiuhou; Burns, Alan; Dou, Xiankang; Xu, JiYao;

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

YEAR: 2013     DOI: 10.1002/jgra.50195

auroral morphology; corotating interaction regions; solar wind/IMF forcing

The GOLD Science Data Center-Algorithm Heritage, Data Product Descriptions and User Services

Lumpe, JD; Foroosh, H; Eastes, R; Krywonos, A; Evans, JS; Burns, AG; Strickland, DJ; Daniell, RE; England, S; Solomon, SC; , others;

Published by:       Published on:

YEAR: 2013     DOI:

Future Needs for Remote Sensing in Heliophysics: Photonic Observations

DeLuca, EE; Paxton, L;

Published by:       Published on:

YEAR: 2013     DOI:

Ionospheric and thermospheric variations associated with prompt penetration electric fields

Lu, G.; Goncharenko, L.; Nicolls, M.; Maute, A.; Coster, A.; Paxton, L.;

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

YEAR: 2012     DOI: 10.1029/2012JA017769

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

Bright polar mesospheric clouds formed by main engine exhaust from the space shuttle's final launch

Stevens, Michael; Lossow, Stefan; Fiedler, Jens; Baumgarten, Gerd; übken, Franz-Josef; Hallgren, Kristofer; Hartogh, Paul; Randall, Cora; Lumpe, Jerry; Bailey, Scott; Niciejewski, R.; Meier, R.; Plane, John; Kochenash, Andrew; Murtagh, Donal; Englert, Christoph;

Published by: Journal of Geophysical Research: Atmospheres      Published on: Apr-10-2013

YEAR: 2012     DOI: 10.1029/2012JD017638

Annual and semiannual variations of thermospheric density: EOF analysis of CHAMP and GRACE data

Lei, Jiuhou; Matsuo, Tomoko; Dou, Xiankang; Sutton, Eric; Luan, Xiaoli;

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

YEAR: 2012     DOI:

Reversed two-cell convection in the northern and southern hemisphere during northward IMF

Lu, G; Li, W; Raeder, J; Deng, Y; Rich, F; Ober, D; Zhang, Y; Paxton, L; Ruohoniemi, M; Hairston, M; , others;

Published by:       Published on:

YEAR: 2012     DOI:

Evolution in space and time of the quasi-static acceleration potential of inverted-V aurora and its interaction with Alfv\ enic boundary processes

Marklund, G.; Sadeghi, S.; Cumnock, J.; Karlsson, T.; Lindqvist, P.-A.; Nilsson, H.; Masson, A.; Fazakerley, A.; Lucek, E.; Pickett, J.; Zhang, Y.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2011JA016537

Evolution in space and time of the quasi-static acceleration potential of inverted-V aurora and its interaction with Alfv\ enic boundary processes

Marklund, G.; Sadeghi, S.; Cumnock, J.; Karlsson, T.; Lindqvist, P.-A.; Nilsson, H.; Masson, A.; Fazakerley, A.; Lucek, E.; Pickett, J.; Zhang, Y.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2011JA016537

Longitudinal variations of nighttime electron auroral precipitation in both the Northern and Southern hemispheres from the TIMED global ultraviolet imager

Luan, Xiaoli; Wang, Wenbin; Burns, Alan; Solomon, Stanley; Zhang, Yongliang; Paxton, L.; Xu, JiYao;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2010JA016051

Rapid recovery of thermosphere density during the October 2003 geomagnetic storms

Lei, Jiuhou; Thayer, Jeffrey; Lu, Gang; Burns, Alan; Wang, Wenbin; Sutton, Eric; Emery, Barbara;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2010JA016164

Reversed two-cell convection in the Northern and Southern hemispheres during northward interplanetary magnetic field

Lu, G.; Li, W.; Raeder, J.; Deng, Y.; Rich, F.; Ober, D.; Zhang, Y.; Paxton, L.; Ruohoniemi, J.; Hairston, M.; Newell, P.;

Published by: Journal of Geophysical Research      Published on: Jan-01-2011

YEAR: 2011     DOI: 10.1029/2011JA017043

Studies of gravity wave and thermal tide and their interactions in the middle atmosphere

Gravity waves (GWs) and tides are two strongest and most persistent waves in the middle atmosphere of the Earth. They are usually generated in the lower atmosphere and propagate

Lu, Xian;

Published by:       Published on:

YEAR: 2011     DOI:

Program of transient UV event research at Tatiana-2 satellite

Garipov, G.; Khrenov, B.; Klimov, P.; Morozenko, V.; Panasyuk, M.; Petrova, S.; Tulupov, V.; Shahparonov, V.; Svertilov, S.; Vedenkin, N.; Yashin, I.; Jeon, J.; Jeong, S.; Jung, A.; Kim, J.; Lee, J.; Lee, H; Na, G.; Nam, J.; Nam, S.; Park, I.; Suh, J.; Jin, J; Kim, M.; Kim, Y.; Yoo, B.; Park, Y.-S.; Yu, H.; Lee, C.-H.; Park, J.; Salazar, H.; Martinez, O.; Ponce, E.; Cotsomi, J.;

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

YEAR: 2010     DOI: 10.1029/2009JA014765

Seasonal and hemispheric variations of the total auroral precipitation energy flux from TIMED/GUVI

Luan, Xiaoli; Wang, Wenbin; Burns, Alan; Solomon, Stanley; Zhang, Yongliang; Paxton, L.;

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

YEAR: 2010     DOI: 10.1029/2009JA015063

Wind and temperature effects on thermosphere mass density response to the November 2004 geomagnetic storm

Lei, Jiuhou; Thayer, Jeffrey; Burns, Alan; Lu, Gang; Deng, Yue;

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

YEAR: 2010     DOI: 10.1029/2009JA014754

Ionospheric E-Region Chemistry and Energetics

Mertens, Christopher; Mlynczak, Martin; Gronoff, Guillaume; Yee, Jeng-Hwa; Swenson, Charles; Fish, Chad; Wellard, Stan; Lumpe, Jerry; Strickland, Doug; Evans, Scott;

Published by: To propose an Earth-observing, multi-satellite science mission to explore the last remaining frontier in upper atmospheric research—the ionospheric E-region      Published on:

YEAR: 2010     DOI:

Integrating the Sun-Earth System for the Operational Environment (ISES-OE)

Lean, J.; Huba, J.; McDonald, S.; Slinker, S.; Drob, D.; Emmert, J.; Meier, R.; Picone, J.; Joyce, G.; Krall, J.; Stephan, A.; Roach, K.; Knight, H.; Plunkett, S.; Wu, C.-C.; Wood, B.; Wang, Y.-M.; Howard, R.; Chen, J.; Bernhardt, P.; Fedder, J.;

Published by:       Published on:

YEAR: 2010     DOI:

Unusual declining phase of solar cycle 23: Weak semi-annual variations of auroral hemispheric power and geomagnetic activity

Luan, Xiaoli; Wang, Wenbin; Burns, Alan; Solomon, Stanley; Zhang, Yongliang; Paxton, L.;

Published by: Geophysical Research Letters      Published on: Jan-01-2009

YEAR: 2009     DOI: 10.1029/2009GL040825

Are Unusual Solar Wind Conditions in SC23-24 Triggering Changes in the Geospace Response to High Speed Streams?

In the descent to solar minimum in solar cycle 23-24, the high-speed streams (HSS) were faster and longer lived than previous cycles but the average IMF was weaker and the average solar wind density lower than ever before recorded upstream of the Earth. A simulation of high speed stream activity on 22-24 January 2005 using the BATS-R-US MHD model with embedded Rice Convection Model driven by solar wind inputs indicates that, at least for this event, the interaction between high speed streams and the magnetosphere has been modified by these unusual solar wind conditions. Northward IMF in the HSS drove the periodic capture of solar wind/magnetosheath plasma in the dayside magnetosphere due to high-latitude reconnection. At times of observed strong periodic auroral activity, a significant IMF By component produced a magnetospheric sash configuration in the simulations in which fingers of enhanced plasma beta were associated with strong field-aligned currents linking to the nightside auroral region. In agreement with the simulations, IMAGE HENA observed low energy (less than tens of keV) hydrogen energetic neutral atoms peaking on the dayside for the 3-days of the high speed stream activity. IMAGE FUV and TIMED GUVI observed periodic auroral activations during the HSS that resembled poleward boundary intensifications (PBIs) rather than the periodic substorms typically associated with HSS. The locations of the observed PBIs in the southern hemisphere were consistent with the high-beta fingers in the near-Earth plasma sheet predicted by the simulation. Particle injection signatures at LANL geosynchronous satellites accompanied the PBIs. To our knowledge, these results provide the first evidence in support of the role of northward IMF in HSS interactions. Based on these results, a study of energetic neutral atom images from TWINS and IMAGE HENA along with observations from other missions in the Heliophysics System Observatory is underway to determine if these characteristics are typical of HSS interactions in the current unusual solar minimum and to search for consequences throughout geospace.

Kozyra, JU; Brandt, PC; Buzulukova, N; de Zeeuw, D; Fok, MH; Frey, HU; Gibson, SE; Ilie, R; Liemohn, MW; Mende, SB; , others;

Published by:       Published on:

YEAR: 2009     DOI:

Reversed ionospheric convections during the November 2004 storm: Impact on the upper atmosphere

Using the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure, a particular period (2000–2350 UT on 9 November) in the November 2004 storm is studied. During this time interval, IMF Bz was strongly northward along with a high solar wind dynamic pressure, favorable conditions to form reversed convection in the polar region. Indeed, the AMIE outputs show strong reversed convection cells in both hemispheres for a long period (>1 h), which have rarely been observed. The impact on the thermospheric neutral wind has been investigated using the AMIE outputs as the electrodynamic inputs of the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model. After the ionospheric convection reversed, the neutral wind distribution at 400 km altitude changed correspondingly, and the difference wind patterns reversed in the polar cap region. By comparing the temporal variations of the difference ion convection and the difference neutral wind, it is found that horizontal neutral winds respond to the reversed convection with some time delay. The neutral wind response time (e-folding time) clearly has an altitudinal dependence varying from 45 min at 400 km altitude to almost 1.5 h at 200 km. The vertical component vorticity has a similar magnitude and distribution to previous studies in the northward Bz condition and changes the sign when the convection pattern is reversed. Comparison between the CHAMP observed cross-track wind and the simulated neutral wind exhibits a general agreement, and the temporal variations of CHAMP cross-track wind indicate a strong effect of the ion drag force on neutral winds.

Deng, Yue; Lu, Gang; Kwak, Young-Sil; Sutton, Eric; Forbes, Jeffrey; Solomon, Stan;

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

YEAR: 2009     DOI: https://doi.org/10.1029/2008JA013793

reversed convection; November 2004 storm

Contrasting Characteristics of the Thermospheric Composition and Density Response to the November 2004 Geomagnetic Storm

Lei, Jiuhou; Thayer, Jeffrey; Burns, Alan; Lu, Gang; Deng, Yue;

Published by: preparation for JGR      Published on:

YEAR: 2009     DOI:

XUV Photometer System (XPS): Improved Solar Irradiance Algorithm Using CHIANTI Spectral Models

Woods, Thomas; Chamberlin, Phillip; Peterson, W.; Meier, R.; Richards, Phil; Strickland, Douglas; Lu, Gang; Qian, Liying; Solomon, Stanley; Iijima, B.; Mannucci, A.; Tsurutani, B.;

Published by: Solar Physics      Published on: Jan-08-2008

YEAR: 2008     DOI: 10.1007/s11207-008-9196-6

GPS observations of the ionospheric F2-layer behavior during the 20th November 2003 geomagnetic storm over South Korea

The ionospheric F2-layer peak density (NmF2) and its height (hmF2) are of great influence on the shape of the ionospheric electron density profile Ne (h) and may be indicative of other physical processes within the ionosphere, especially those due to geomagnetic storms. Such parameters are often estimated using models such as the semiempirical international reference ionosphere (IRI) models or are measured using moderately priced to expensive instrumentation, such as ionosondes or incoherent scatter radars. Global positioning system (GPS) observations have become a powerful tool for mapping high-resolution ionospheric structures, which can be used to study the ionospheric response to geomagnetic storms. In this paper, we describe how 3-D ionospheric electron density profiles were produced from data of the dense permanent Korean GPS network using the tomography reconstruction technique. These profiles are verified by independent ionosonde data. The responses of GPS-derived parameters at the ionospheric F2-layer to the 20th November 2003 geomagnetic storm over South Korea are investigated. A fairly large increase in the electron density at the F2-layer peak (the NmF2) (positive storm) has been observed during this storm, which is accompanied by a significant uplift in the height of the F2 layer peak (the hmF2). This is confirmed by independent ionosonde observations. We suggest that the F2-layer peak height uplift and NmF2 increase are mainly associated with a strong eastward electric field, and are not associated with the increase of the O/N₂ ratio obtained from the GUVI instruments aboard the TIMED satellite. It is also inferred that the increase in NmF2 is not caused by the changes in neutral composition, but is related to other nonchemical effects, such as dynamical changes of vertical ion motions induced by winds and E\ \texttimes\ B drifts, tides and waves in the mesosphere/lower thermosphere region, which can be dynamically coupled upward to generate ionospheric perturbations and oscillations.

Jin, Shuanggen; Luo, O.; Park, P.;

Published by: Journal of Geodesy      Published on: 03/2008

YEAR: 2008     DOI: 10.1007/s00190-008-0217-x

F2-layer; geomagnetic storm; GPS; Ionosphere; Tomography

A data-model comparative study of ionospheric positive storm phase in the midlatitude F region

Lu, G; Goncharenko, LP; Coster, AJ; Richmond, AD; Roble, RG; Aponte, N; Paxton, LJ;

Published by:       Published on:

YEAR: 2008     DOI:

Performing Science Research with the Virtual ITM Observatory

Morrison, D; Weiss, M; Immer, L; Patrone, D; Potter, M; Holder, R; Barnes, R; Colclough, C; Nylund, S; Yee, J; , others;

Published by:       Published on:

YEAR: 2008     DOI:

Variations of Auroral Electron Precipitation Measured by TIMED/GUVI

Luan, X; Wang, W; Burns, A; Zhang, Y; Solomon, S;

Published by:       Published on:

YEAR: 2008     DOI:

Polar rain aurora

Zhang, Yongliang; Paxton, Larry; Lui, Anthony;

Published by: Geophysical research letters      Published on:

YEAR: 2007     DOI: 10.1029/2007GL031602

Prelude to THEMIS tail conjunction study

Lui, ATY; Zheng, Y; Zhang, Y; , Angelopoulos; Parks, GK; Mozer, FS; Reme, H; Kistler, LM; Dunlop, MW; Gustafsson, Georg; , others;

Published by:       Published on:

YEAR: 2007     DOI:

Enabling Science with the Virtual ITM Observatory

Morrison, D; Weiss, M; Immer, L; Holder, R; Barnes, R; Colclough, C; Potter, M; Daley, R; Hashemian, M; Nylund, S; , others;

Published by:       Published on:

YEAR: 2007     DOI:

Equatorial plasma bubbles in the ionosphere over Eritrea: occurrence and drift speed

Wiens, R.; Ledvina, B.; Kintner, P.; Afewerki, M.; Mulugheta, Z.;

Published by: Annales Geophysicae      Published on: Jan-01-2006

YEAR: 2006     DOI: 10.5194/angeo-24-1443-2006

The HEX experiment: Determination of the neutral wind field from 120 to 185 km altitude near a stable premidnight auroral arc by triangulating the drift of rocket-deployed chemical trails

Wescott, E.; Stenbaek-Nielsen, H.; Conde, M.; Larsen, Miguel; Lummerzheim, Dirk;

Published by: Journal of Geophysical Research      Published on: Jan-01-2006

YEAR: 2006     DOI: 10.1029/2005JA011002

VITMO: A Virtual Observatory for the ITM Community

Morrison, D; Weiss, M; Daley, R; Immer, L; Nylund, S; Yee, J; Talaat, E; Russell, J; Heelis, R; Kozyra, J; , others;

Published by:       Published on:

YEAR: 2006     DOI:

An unusual nightside distortion of the auroral oval: TIMED/GUVI and IMAGE/FUV observations

Zhang, Y; Paxton, LJ; Lui, ATY;

Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012)      Published on:

YEAR: 2006     DOI: