GUVI Biblio


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Found 58 entries in the Bibliography.

Showing entries from 1 through 50


The Far Ultraviolet Signatures of Conjugate Photoelectrons Seen by the Special Sensor Ultraviolet Spectrographic Imager

This study investigates the origin of anomalous far ultraviolet emissions observed at night at the subauroral region by the Special Sensor Ultraviolet Spectrographic Imager on board the Defense Meteorological Satellite System-F16 satellite. The global distribution of the anomalous emission is derived using the measurements of the oxygen atom 130.4-nm emission in 2017. Our results show the extension of the anomalous emission from high latitudes to middle latitudes in the Northern American-Atlantic sector during the Decembe ...

Kil, Hyosub; Schaefer, Robert; Paxton, Larry; Jee, Geonhwa;

YEAR: 2020     DOI: 10.1029/2019GL086383

conjugate photoelectron; far ultraviolet emission; thermosphere; remote sensing data

Impacts of Binning Methods on High-Latitude Electrodynamic Forcing: Static Versus Boundary-Oriented Binning Methods

An outstanding issue in the general circulation model simulations for Earth\textquoterights upper atmosphere is the inaccurate estimation of Joule heating, which could be associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. The binning methods used to develop those empirical models may contribute to the inaccuracy. Traditionally, data are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is ...

Zhu, Qingyu; Deng, Yue; Richmond, Arthur; Maute, Astrid; Chen, Yun-Ju; Hairston, Marc; Kilcommons, Liam; Knipp, Delores; Redmon, Robert; Mitchell, Elizabeth;

YEAR: 2020     DOI: 10.1029/2019JA027270

Electric field; high latitude; Joule heating; particle precipitation


Plasma Blobs Associated With Medium-Scale Traveling Ionospheric Disturbances

Plasma blobs represent plasma density enhancements with respect to ambient plasma. The formation of blobs in low and middle latitudes is understood in association with either equatorial plasma bubbles or medium-scale traveling ionospheric disturbances (MSTIDs). This study reports four blob events identified from the Swarm satellite observations in 2014. Those blobs show the conjugate property and the alignment in the northwest-southeast direction in the Northern Hemisphere and southwest-northeast direction in the Southern ...

Kil, Hyosub; Paxton, Larry; Jee, Geonhwa; Nikoukar, Romina;

YEAR: 2019     DOI: 10.1029/2019GL082026


Tropical Ionization Trough in the Ionosphere Seen by Swarm-A Satellite

A new type of ionization trough, the tropical ionization trough, is identified in the tropical F region from the Swarm-A satellite observations in December 2013 to January 2017. The trough is formed around midnight near 25\textdegree magnetic latitudes in the winter hemisphere during the solstices. The trough is pronounced around 330\textdegreeE longitude in the Southern Hemisphere (negative magnetic declination) during the June solstices and around 210\textdegreeE longitude in the Northern Hemisphere (p ...

Lee, Woo; Kil, Hyosub; Paxton, Larry;

YEAR: 2018     DOI: 10.1029/2018GL080286


Far ultraviolet instrument technology

The far ultraviolet (FUV) spectral range (from about 115 nm to 180 nm) is one of the most useful spectral regions for characterizing the upper atmosphere (thermosphere and ionosphere). The principal advantages are that there are FUV signatures of the major constituents of the upper atmosphere as well as the signatures of the high-latitude energy inputs. Because of the absorption by thermospheric O2, the FUV signatures are seen against a \textquotedblleftblack\textquotedblright background, i.e., one that is not ...

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

YEAR: 2017     DOI: 10.1002/jgra.v122.210.1002/2016JA023578


The Morphology of Equatorial Plasma Bubbles - a review

Plasma bubbles that occur in the equatorial F-region make up one of the most distinguishing phenomena in the ionosphere. Bubbles represent plasma depletions with respect to the background ionosphere, and are the major source of electron density irregularities in the equatorial F-region. Such bubbles are seen as plasma depletion holes (in situ satellite observations), vertical plumes (radar observations), and emission-depletion bands elongated in the north-south direction (optical observations). However, no technique can o ...

Kil, Hyosub;

YEAR: 2015     DOI: 10.5140/JASS.2015.32.1.13

Equatorial ionosphere; irregularities; plasma bubble

Remote Sensing of Earth\textquoterights Limb by TIMED/GUVI: Retrieval of thermospheric composition and temperature

The Global Ultraviolet Imager (GUVI) onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite senses far ultraviolet emissions from O and N2 in the thermosphere. Transformation of far ultraviolet radiances measured on the Earth limb into O, N2, and O2 number densities and temperature quantifies these responses and demonstrates the value of simultaneous altitude and geographic information. Composition and temperature variations are available from 2002 to 2007 ...

Meier, R.; Picone, J.; Drob, D.; Bishop, J.; Emmert, J.; Lean, J.; Stephan, A.; Strickland, D.; Christensen, A.; Paxton, L.; Morrison, D.; Kil, H.; Wolven, B.; Woods, Thomas; Crowley, G.; Gibson, S.;

YEAR: 2015     DOI: 10.1002/2014EA000035

airglow and aurora; remote sensing; thermosphere: composition and chemistry; thermosphere: energy deposition


Geomagnetic control of equatorial plasma bubble activity modeled by the TIEGCM with Kp

Describing the day-to-day variability of Equatorial Plasma Bubble (EPB) occurrence remains a significant challenge. In this study we use the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM), driven by solar (F10.7) and geomagnetic (Kp) activity indices, to study daily variations of the linear Rayleigh-Taylor (R-T) instability growth rate in relation to the measured scintillation strength at five longitudinally distributed stations. For locations characterized ...

Carter, B.; Retterer, J.; Yizengaw, E.; Groves, K.; Caton, R.; McNamara, L.; Bridgwood, C.; Francis, M.; Terkildsen, M.; Norman, R.; Zhang, K.;

YEAR: 2014     DOI: 10.1002/2014GL060953

Equatorial ionosphere; plasma bubbles; TIEGCM

Storm-time behaviors of O/N2 and NO variations

Algorithms have been developed to extract net nitric oxide (NO) radiances in the wavelength range of 172\textendash182\ nm from the dayside TIMED/GUVI spectrograph data and convert them to NO column density (100\textendash150\ km). The thermospheric O/N2 column density ratios (referenced from an altitude ~135\ km with a N2column density of 1017\ cm-2) are also obtained from the spectrograph data. The spatial resolution of the NO and O/N2 products a ...

Zhang, Y.; Paxton, L.J.; Morrison, D.; Marsh, D.; Kil, H.;

YEAR: 2014     DOI: 10.1016/j.jastp.2014.04.003

geomagnetic storm; Thermospheric nitric oxide; Thermospheric O/N2 ratio

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.;

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

equatorial plasma bubbles; GPS scintillation; Ionosphere


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.;

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;

YEAR: 2013     DOI: 10.1002/2013JA019132

geomagnetic storm; GUVI O/N2 ratio; ionospheric effect

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;

YEAR: 2013     DOI: 10.1002/grl.50693

bubbles; Equatorial ionosphere; irregularities

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;

YEAR: 2013     DOI: 10.1002/jgra.50327

GUVI; Ionosphere; UV imager

Multi-Periodic Auroral and Thermospheric Variations in 2006

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

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


A long-lived band of plasma density enhancement at mid-latitudes during the 2003 Halloween magnetic storm

Park, Jaeheung; Lühra, Hermann; Jakowski, Norbert; Gerzen, Tatjana; Kil, Hyosub; Jee, Geonhwa; Xiong, Chao; Min, Kyoung; Noja, Max;

YEAR: 2012     DOI: 10.1016/j.jastp.2012.03.009

The source of the steep plasma density gradient in middle latitudes during the 11\textendash12 April 2001 storm

A steep plasma density gradient has been observed in the middle-latitude F region during large geomagnetic storms. This phenomenon can be understood as a special form of the middle-latitude ionization trough (hereafter trough), but its causal linkage has not yet been clarified. We investigate the association of the steep density gradient and the trough by comparing their morphologies and occurrence locations using the satellite and ground observation data during the 11\textendash12 April 2001 storm. Steep density ...

Park, S.; Kim, K.-H.; Kil, H.; Jee, G.; Lee, D.-H.; Goldstein, J.;

YEAR: 2012     DOI: 10.1029/2011JA017349

geomagnetic storm; plasma trough; steep density gradient


The origin of the nonmigrating tidal structure in the column number density ratio of atomic oxygen to molecular nitrogen

Kil, Hyosub; Paxton, L.;

YEAR: 2011     DOI: 10.1029/2011GL049432

Nightside polar rain aurora boundary gap and its applications for magnetotail reconnection

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

YEAR: 2011     DOI: 10.1029/2011JA016884

O and N 2 disturbances in the F region during the 20 November 2003 storm seen from TIMED/GUVI

Kil, H.; Kwak, Y.-S.; Paxton, L.; Meier, R.; Zhang, Y.;

YEAR: 2011     DOI: 10.1029/2010JA016227

The source of the longitudinal asymmetry in the ionospheric tidal structure

Kil, H.; Kwak, Y.-S.; Oh, S.-J.; Talaat, E.; Paxton, L.; Zhang, Y.;

YEAR: 2011     DOI: 10.1029/2011JA016781

Temporal and spatial components in the storm-time ionospheric disturbances

Kil, Hyosub; Paxton, L.; Kim, Khan-Hyuk; Park, Sarah; Zhang, Yongliang; Oh, Seung-Jun;

YEAR: 2011     DOI: 10.1029/2011JA016750

Causal Link of Longitudinal Plasma Density Structure to Vertical Plasma Drift and Atmospheric Tides \textendash A Review

This chapter reviews recent advances in our understanding of the characteristics and driving mechanisms of the longitudinal plasma density structure in the low-latitude F region. Various ionospheric observations have shown the development of a longitudinal wave-like pattern in plasma density. Typically, the wave number-4 (wave-4) pattern is pronounced during July\textendashSeptember, and the wave-3 pattern is pronounced during December\textendashJanuary. Variation of the longitudinal plasma density pattern with l ...

Kil, Hyosub; Paxton, Larry;

YEAR: 2011     DOI: 10.1007/978-94-007-0326-1_26


The temporal evolution of the large equatorial plasma depletions observed during the 29\textendash30 October 2003 storm

Kil, Hyosub; Paxton, L.;

YEAR: 2010     DOI: 10.1016/j.jastp.2009.10.019

Is DE2 the source of the ionospheric wave number 3 longitudinal structure?

Kil, H.; Paxton, L.; Lee, W.; Ren, Z.; Oh, S.-J.; Kwak, Y.-S.;

YEAR: 2010     DOI: 10.1029/2010JA015979


Formation of a plasma depletion shell in the equatorial ionosphere

An accurate description of the irregularity region defined by a plasma bubble is critically important in understanding the dynamics of the region and its effects on radio scintillation. Here we describe a plasma depletion region as a \textquotedblleftdepletion shell\textquotedblright and show how two-dimensional optical images from space can be used to define the shape of the depletion shell. Our simple model calculation demonstrates that the space-based optical observation can detect the plasma-depleted magnetic flux tub ...

Kil, Hyosub; Heelis, Roderick; Paxton, Larry; Oh, Seung-Jun;

YEAR: 2009     DOI: 10.1029/2009JA014369

Equatorial ionosphere; plasma depletion shell; zonal shear flow


Effects of solar activity variations on the low latitude topside nighttime ionosphere

Park, S.M.; Kim, H.; Min, S.; Park, J.; Lee, J.H.; Kil, H.; Paxton, L.; Su, S.-Y.; Lee, J.; Min, K.W.;

YEAR: 2008     DOI: 10.1016/j.asr.2007.11.031

Wave structures of the plasma density and vertical E \texttimes B drift in low-latitude F region

Kil, H.; Talaat, E.; Oh, S.-J.; Paxton, L.; England, S.; Su, S.-Y.;

YEAR: 2008     DOI: 10.1029/2008JA013106


A climatology of nonmigrating semidiurnal tides from TIMED Doppler Interferometer (TIDI) wind data

Oberheide, J.; Wu, Q.; Killeen, T.L.; Hagan, M.E.; Roble, R.G.;

YEAR: 2007     DOI: 10.1016/j.jastp.2007.05.010

The ionospheric and thermospheric response to CMEs: Challenges and successes

Burns, A.G.; Solomon, S.C.; Wang, W.; Killeen, T.L.;

YEAR: 2007     DOI: 10.1016/j.jastp.2006.06.010


F-region Pedersen conductivity deduced using the TIMED/GUVI limb retrievals

Kil, H.; DeMajistre, M.; Paxton, L.; Zhang, Y.;

YEAR: 2006     DOI: 10.5194/angeo-24-1311-2006

Nightside thermospheric FUV emissions due to energetic neutral atom precipitation during magnetic superstorms

Zhang, Y.; Paxton, L.; Kozyra, J.; Kil, H.; Brandt, P.;

YEAR: 2006     DOI: 10.1029/2005JA011152

Ionospheric disturbances during the magnetic storm of 15 July 2000: Role of the fountain effect and plasma bubbles for the formation of large equatorial plasma density depletions

We investigate the role of the fountain effect and plasma bubbles for the formation of the large equatorial plasma depletions during the geomagnetic storm of 15 July 2000. The large equatorial plasma depletions are detected in the Atlantic sector on the night of the 15th by the Defense Meteorological Satellite Program (DMSP) F15 and the first Republic of China Satellite (ROCSAT-1). The observations show discontinuous drop of the plasma density at the walls of the depletions, flat plasma density inside the depletions, and ...

Kil, Hyosub; Paxton, Larry;

YEAR: 2006     DOI: 10.1029/2006JA011742

Equatorial ionosphere; geomagnetic storm; ionospheric disturbances

Characteristics of the storm-induced big bubbles (SIBBs)

Large equatorial plasma depletions, referred to as storm-induced big bubbles (SIBBs), are detected from the Defense Meteorological Satellite Program F15 and from the first Republic of China Satellite during the large magnetic storms of 31 March 2001, 29 October 2003, and 20 November 2003. They occur in the equatorial region at night, are elongated in the north-south direction, have steep walls, and always coexist with plasma bubbles. These observations are consistent with the SIBB characteristics described in the companio ...

Kil, Hyosub; Paxton, L.; Su, Shin-Yi; Zhang, Yongliang; Yeh, Hweyching;

YEAR: 2006     DOI: 10.1029/2006JA011743

Equatorial ionosphere; geomagnetic storm; irregularities

Nighttime F-region morphology in the low and middle latitudes seen from DMSP F15 and TIMED/GUVI

We investigate the seasonal, longitudinal, and altitudinal variations of the FF-region morphology at 2100\textendash2300\ LT in the low- and middle-latitudes using the data collected in August, September, and November of 2003. The topside morphology is investigated using in situ measurements of the O+O+ fraction and total ion density by the Defense Meteorological Satellite Program (DMSP) F15 satellite. The morphology of the equatorial ionization anomaly (EIA) near the FF peak altitude is investigated using ...

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

YEAR: 2006     DOI: 10.1016/j.jastp.2006.05.024

Equatorial ionization anomaly; FF-region plasma distribution; low-latitude ionosphere; Neutral wind

Effects of Solar Activity Variations on the Low Latitude Topside Nighttime Ionosphere

Min, K.; Kim, H.; Park, J.; Kil, H.; Lee, J.; Lee, E.;

YEAR: 2006     DOI:


Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations

Undulations on the equatorward edge of the diffuse proton aurora have been identified by using TIMED/GUVI auroral images in the far ultraviolet wavelengths. While undulations have been previously reported on the duskside (Lui et al., 1982), GUVI observations show the undulation also occurs in the dayside, nightside, and morningside. The GUVI proton auroral images provide direct optical evidence that the undulations occur in the proton aurora. It is also the first detection of the undulation in the dayside indicating stron ...

Zhang, Y.; Paxton, L.; Morrison, D.; T. Y. Lui, A.; Kil, H.; Wolven, B.; Meng, C.-I.; Christensen, A.;

YEAR: 2005     DOI: 10.1029/2004JA010668

auroral undulation; K-H instability; Magnetic storm; plasma convection

Far-ultraviolet signature of polar cusp during southward IMF Bz observed by TIMED/Global Ultraviolet Imager and DMSP

The coincident TIMED/Global Ultraviolet Imager (TIMED/GUVI) optical and DMSP particle observations have revealed new features of the optical signature of the polar cusp under a southward interplanetary magnetic field (IMF). We have found that cusp auroras usually take the shape of a thin arc with a width around 100\textendash200 km. This provides the first far-ultraviolet evidence of the narrow cusp under a southward IMF [

Zhang, Y; Meng, C-I; Paxton, LJ; Morrison, D; Wolven, B; Kil, H; Newell, P; Wing, S; Christensen, AB;

YEAR: 2005     DOI: 10.1029/2004JA010707

cusp aurora

GUVI Observations of storm-time control and coupling of the ionosphere and thermosphere

Paxton, L.; Kil, H.; DeMajistre, R.; Zhang, Y.;

YEAR: 2005     DOI:

Imaging the Low-Latitude Ionosphere: Future Collaborations with C/NOFS

Paxton, L.; Kil, H.; DeMajistre, R.; Zhang, Y.; Morrison, D.; Wolven, B.; Meng, C.-I;

YEAR: 2005     DOI:

Nightside detached auroras due to precipitating protons/ions during intense magnetic storms

Nightside detached auroras (NDA) during intense magnetic storms are studied by using FUV image data from Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED)/Global Ultraviolet Imager (GUVI), Imager for Magnetopause-to-Aurora Global Exploration (IMAGE)/FUV, and particle data from DMSP/SSJ/4 instruments. We found that NDA are caused by proton/ion precipitation only. Thin arc-shaped NDA are very likely due to soft (\<1 keV) proton/ion precipitation. Thick or patch-shaped NDA are caused by energetic (\~10 ke ...

Zhang, Y; Paxton, LJ; Morrison, D; Wolven, B; Kil, H; Wing, S;

YEAR: 2005     DOI: 10.1029/2004JA010498

detached aurora; proton precipitation; ring current; Magnetic storm

TIMED/GUVI Observations of the Ionosphere and Thermosphere Interaction

Paxton, L.; Kil, H.; DeMajistre, R.; Zhang, Y.; Morrison, D.; Wolven, B.; Meng, C.-I.;

YEAR: 2005     DOI:


Coincident equatorial bubble detection by TIMED/GUVI and ROCSAT-1

Kil, Hyosub; Su, S.-Y.; Paxton, L.; Wolven, B.; Zhang, Y.; Morrison, D.; Yeh, H.;

YEAR: 2004     DOI: 10.1029/2003GL018696

O/N 2 changes during 1\textendash4 October 2002 storms: IMAGE SI-13 and TIMED/GUVI observations

Thermospheric O/N2 column density ratios referenced at a N2 column density of 1017 cm-2 are obtained using the IMAGE SI-13 and TIMED/GUVI far-ultraviolet (FUV) dayglow data, AURIC simulation results, and MSIS86 model. Each of the magnetic storms occurring during a 4-day period (1\textendash4 October 2002) caused significant O/N2 depletion that was detected by both of the IMAGE SI-13 and GUVI instruments. The depletion extended down to latitudes of 10\textdegree and -5 ...

Zhang, Y.; Paxton, L.; Morrison, D.; Wolven, B.; Kil, H.; Meng, C.-I.; Mende, S.; Immel, T.;

YEAR: 2004     DOI: 10.1029/2004JA010441

Magnetic storm; thermospheric composition change

Double dayside detached auroras: TIMED/GUVI observations

On August 19, 2003, TIMED/GUVI detected, for the first time, two separated (double) dayside detached auroras (D-DDA) simultaneously in all the GUVI channels, 121.6 nm, 135.6 nm, LBHS, and LBHL. The D-DDA was located at magnetic latitudes around -57\textdegree and -63\textdegree (L shell 3.4 and 4.9) in the 0900\textendash1030 MLT region. The high-latitude part of the D-DDA is much brighter than the low-latitude part. DMSP particle observation indicates that the source of the D-DDA is energetic (\~10 keV) precipitating pro ...

Zhang, Y.; Paxton, L.; Meng, C.-I.; Morrison, D.; Wolven, B.; Kil, H.; Christensen, A.;

YEAR: 2004     DOI: 10.1029/2003GL018949

F -region plasma distribution seen from TIMED/GUVI and its relation to the equatorial spread F activity

The OI 135.6-nm nightglow images from GUVI on board the TIMED satellite provide a unique opportunity to investigate the global plasma distribution in the F region. We report that there exist large seasonal-longitudinal variations in the F-region plasma density which may explain some aspects of the equatorial spread F (ESF) morphology. We suggest that an occurrence of high plasma density is responsible for the strong ESF activity during equinox periods at most longitudes, whereas an occurrence of ...

Kil, Hyosub; DeMajistre, Robert; Paxton, L.;

YEAR: 2004     DOI: 10.1029/2003GL018703

GUVI: a hyperspectral imager for geospace

The Global Ultraviolet Imager (GUVI) is an imaging spectrometer on the NASA TIMED spacecraft which was launched on December 7, 2001. This instrument produces a far ultraviolet (FUV) data cube of spatial and spectral information at each step of a scan mirror - that scan mirror covers 140 deg in the cross track direction - a span that includes on limb. GUVI produces simultaneous monochromatic images at five "colors" (121.6 nm, 130.4 nm, 135.6 nm, and in broader bands at 140-150 nm and 165-180 nm) as its field of view is sca ...

Paxton, L.; Christensen, Andrew; Morrison, Daniel; Wolven, Brian; Kil, Hyosub; Zhang, Yongliang; Ogorzalek, Bernard; Humm, David; Goldsten, John; DeMajistre, Robert; Meng, Ching-I.;

YEAR: 2004     DOI: 10.1117/12.579171


The use of far ultraviolet remote sensing to monitor space weather

This paper discusses the connection between changes in Earth\textquoterights thermosphere and ionosphere induced by changes in the Earth\textquoterights local space environment (or \textquotedblleftspace weather\textquotedblright) and the phenomena observed in far ultraviolet images of the Earth. Two new experiments, the Global Ultraviolet Imager (GUVI) and the Special Sensor Ultraviolet Imager (SSUSI), will provide a new capability for monitoring changes in thermospheric composition and ionospheric density as they change ...

Paxton, L.; Morrison, Daniel; Strickland, Douglas; McHarg, M.Geoff; Zhang, Yongliang; Wolven, Brian; Kill, Hyosub; Crowley, Geoff; Christensen, Andrew; Meng, Ching-I;

YEAR: 2003     DOI: 10.1016/S0273-1177(02)00886-4

Case study of the 15 July 2000 magnetic storm effects on the ionosphere-driver of the positive ionospheric storm in the winter hemisphere

The ionospheric response to the magnetic storm of 15 July 2000 is investigated using the global total electron content (TEC) maps provided by global positioning system and the measurements of ion density, composition, and drift velocity from the Defense Meteorological Satellite Program (DMSP) F13 and F15 spacecraft. The global TEC maps showed clear seasonal effects that can be characterized by a dominance of a negative ionospheric storm (decrease in plasma density) in the summer (northern) hemisphere and the pronounced po ...

Kil, Hyosub; Paxton, L.; Pi, X.; Hairston, M.; Zhang, Y.;

YEAR: 2003     DOI: 10.1029/2002JA009782

ionosphere-thermosphere coupling; Ionospheric storm; thermospheric disturbance

The first coordinated ground- and space-based optical observations of equatorial plasma bubbles

We report on ionospheric optical emissions detected by the GUVI instrument on the TIMED satellite. As the satellite crosses the equatorial zone the bright Appleton Anomaly region is imaged. Often these bright zones are interrupted by regions slanted from west to east as the equator is approached forming a backwards \textquoteleftC\textquoteright-shape in the image. To explain this feature we use simultaneous ground-based observations looking equatorward from Hawaii using the 777.4-nm emission. We also compare these optica ...

Kelley, Michael; Makela, J.; Paxton, L.; Kamalabadi, F.; Comberiate, J.; Kil, H.;

YEAR: 2003     DOI: 10.1029/2003GL017301

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