Bibliography

Notice:

Clicking on the title will open a new window with all details of the bibliographic entry.
Clicking on the DOI link will open a new window with the original bibliographic entry from the publisher.
Clicking on a single author will show all publications by the selected author.
Clicking on a single keyword, will show all publications by the selected keyword.

Found 215 entries in the Bibliography.

Showing entries from 151 through 200

2005

Observations of solar and magnetospheric inputs and atmospheric responses to the January 2005 long duration flares and fast coronal mass ejections

Paxton, LJ; Kozyra, J; Demajistre, B; Kil, H; Morrison, D; Wolven, B; Mitchell, D; Brandt, P; Zhang, Y; Meng, C;

Published by: Published on:

YEAR: 2005 DOI:

2004

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.;

Published by: Geophysical Research Letters Published on: Jan-01-2004

YEAR: 2004 DOI: 10.1029/2003GL018696

O/N ₂ changes during 1--4 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\textdegree in the Northern and Southern Hemispheres, respectively. Simultaneous measurements show an excellent agreement between the SI-13 and GUVI O/N₂ on both global and local scales. The IMAGE SI-13 O/N₂ data provide direct optical evidence that the O/N₂ depletion corotates with the Earth. The GUVI O/N₂ indicate the depletion in both of the hemispheres is not symmetric owing to the seasonal effect and differences in heating and convection induced winds. Both the IMAGE SI-13 and GUVI O/N₂ maps also provide a good opportunity for future modeling efforts.

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

Published by: Journal of Geophysical Research Published on: 10/2004

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 protons/electrons from the ring current due to the solar wind dynamic pressure enhancements [Zhang et al., 2002] and/or northward turning of the IMF B_z. Observations of the D-DDA provide the first single-event evidence of multiple peaks in the statistical distribution of proton fluxes at energetic around and below 10 keV at low L-shells [Milillo et al., 2001].

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

Published by: Geophysical Research Letters Published on: 05/2004

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 low plasma density is responsible for the suppressed ESF activity during northern summer in the American-Atlantic sector.

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

Published by: Geophysical Research Letters Published on: 03/2004

YEAR: 2004 DOI: 10.1029/2003GL018703

GUVI/TIMED Observations of the auroral inputs and thermospheric response during the October and November 2003 Superstorms

Zhang, Y; Paxton, LJ; Kozyra, JU; DeMajistre, R; Kil, H; Morrison, D; Wolven, B; Brandt, PC; Mitchell, DG; Talaat, E;

Published by: Published on:

YEAR: 2004 DOI:

Statistical Analysis of Equatorial Spread F Activity Seen From TIMED/GUVI

Comberiate, JM; Krekeler, JM; Kamalabadi, F; Paxton, LJ; Kil, H;

Published by: Published on:

YEAR: 2004 DOI:

A climatology of the nighttime ionosphere acquired by the TIMED/GUVI instrument and the changes associated with storm time

DeMajistre, R; Kil, H; Paxton, LJ;

Published by: Published on:

YEAR: 2004 DOI:

Observational and Modeling Analysis of the Coupling Between Neutral Winds and the Low-Latitude Ionosphere

Talaat, ER; DeMajistre, R; Yee, J; Paxton, LJ; Crowley, G; Palo, S; Christensen, AB; Azeem, I; Roble, R; Kil, H; , others;

Published by: Published on:

YEAR: 2004 DOI:

Observations of the Ionospheric and Thermospheric Response During the October and November 2003 Storms

Paxton, L; Crowley, G; Zhang, Y; DeMajistre, R; Kil, H; Morrison, D; Wolven, B; Straus, P; Christensen, A;

Published by: Published on:

YEAR: 2004 DOI:

Far Ultraviolet Imaging of the low-Latitude Nightside Ionosphere with the GUVI Instrument on TIMED

Paxton, LJ; Kil, H; DeMajistre, R; Morrison, D; Straus, P; Talaat, E; Christensen, A; Wolven, B; Zhang, Y; Crowley, G; , others;

Published by: Published on:

YEAR: 2004 DOI:

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

Kil, Hyosub; DeMajistre, Robert; Paxton, Larry;

Published by: Geophysical research letters Published on:

YEAR: 2004 DOI:

The nighttime F-region climatology during magnetically quiet periods seen from TIMED/GUVI and DMSP

Kil, H; Paxton, L; Zhang, Y; Wolven, B; Morrison, D;

Published by: Published on:

YEAR: 2004 DOI:

Storm-time modifications of the mid-latitude nighttime ionosphere measured by the TIMED/GUVI instrument

Eichert, J; DeMajistre, R; Paxton, LJ; Kil, H; Talaat, E;

Published by: Published on:

YEAR: 2004 DOI:

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 scanned from horizon to horizon. The instrument consists of a scan mirror feeding a parabolic telescope and Rowland circle spectrometer, with a wedge-and-strip detector at the focal plane. We describe the design, and give an overview of the environmental parameters that will be measured. GUVI is a modified version of the Special Sensor Ultraviolet Spectrographic Imager (SSUSI), which was launched on the DMSP Block 5D3 F16 satellite on October 18, 2003 and is slated to fly on DMSP satellites F17 through F20, as well. We present some results the science analysis of the GUVI data to demonstrate its relevance to the space weather community.

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

Published by: Published on:

YEAR: 2004 DOI: 10.1117/12.579171

2003

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 in response to space weather. These sensors provide a ten-fold improvement in spatial and temporal resolution and a greater than ten-fold improvement in sensitivity over that provided by sensors on the POLAR and IMAGE satellites. These sensors are expected to provide new insights into the mesoscale coupling between the ionosphere and thermosphere, as well as allowing us to develop a better specification of the high latitude convection electric field pattern.

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

Published by: Advances in Space Research Published on: Jan-01-2003

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 positive ionospheric storm (increase in plasma density) in the winter (southern) hemisphere. The northern negative storm phase rapidly expanded to the equator at midnight and even penetrated to the opposite hemisphere during the storm main phase. In the southern hemisphere, the negative storm phase began in the morning sector but was confined to narrow latitude and local time sectors owing to strong poleward winds and ion drag on the dayside. The negative storm phases in the opposite hemispheres kept out of phase, lasted for a day, and corotated with Earth. These characteristics show good qualitative similarity with the predictions of global model simulations. The positive storm phase prevailed in the southern low-middle latitudes and was most pronounced during nighttime. In that region, the quiet time DMSP measurements at 1800 LT, 2100 LT, 0600 LT, and 0900 LT showed low ion density, low O⁺ proportion, and large downward ion drift velocity compared with those in the northern hemisphere. During storm time the O⁺ proportion and ion concentration increased to the levels seen in the northern hemisphere while the downward ion drift velocity was much decreased. The excellent temporal and spatial correspondence of the increase in ion concentration with the decrease in downward ion drift velocity indicates that the maintenance of the F layer at high altitudes by the storm-induced equatorward neutral winds was the main driver of the positive ionospheric storm. The quiet time hemispheric asymmetry was most significant at nighttime, and therefore the positive storm effect appeared most pronounced at nighttime in the winter hemisphere.

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

Published by: Journal of Geophysical Research Published on: 11/2003

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 optical observations to inverted electron density maps, as well as to those made by radar and to numerical simulations of the Rayleigh-Taylor instability. The characteristic shape is a result of a shear in the eastward plasma flow velocity, which peaks near the F peak at the equator and decreases both above and below that height. The ability to detect these unstable and usually turbulent ionospheric regions from orbit provides a powerful global remote sensing capability for an important space weather process.

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

Published by: Geophysical Research Letters Published on: 07/2003

YEAR: 2003 DOI: 10.1029/2003GL017301

Automatic Detection of Equatorial Plasma Bubbles in GUVI Data

Henderson, S; Swenson, C; Straus, P; Kil, H; Christensen, A; Paxton, L; Morrison, D; Crowley, G; Meier, R; Craven, J; , others;

Published by: Published on:

YEAR: 2003 DOI:

Space Weather Effects of the April 15-23 2002 Geomagnetic Storm

Hackert, C; Crowley, G; Paxton, L; Christensen, A; Kil, Y; Zhang, Y; Morrison, D; Goncharenko, L; Makela, J; Sahai, Y; , others;

Published by: Published on:

YEAR: 2003 DOI:

TIMED instruments

Yee, Jeng-Hwa; Talaat, Elsayed; Christensen, Andrew; Killeen, Timothy; Russell, James; Woods, Thomas;

Published by: Johns Hopkins APL Technical Digest Published on:

YEAR: 2003 DOI:

TIMED science: First light

Talaat, Elsayed; Yee, Jeng-Hwa; Christensen, Andrew; Killeen, Timothy; Russell, James; Woods, Thomas;

Published by: Johns Hopkins APL technical digest Published on:

YEAR: 2003 DOI:

F-Region Plasma Distribution seen from TIMED/GUVI and its Effect on the Equatorial Spread F Activity

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

Published by: Published on:

YEAR: 2003 DOI:

TIMED/GUVI and DMSP/SSUSI-Operational Data Products for Space Weather

Hsieh, Syau-Yun; Paxton, Larry; Zhang, Yongliang; Schaefer, Robert; DeMajistre, Robert; Wolven, Brian; Morrison, Daniel; Comberiate, Joseph; Kil, Hyosub;

Published by: Published on:

YEAR: 2003 DOI:

GUVI nighttime observations of the equatorial and mid-latitude ionosphere

Straus, PR; Paxton, LJ; Crowley, G; Henderson, S; Kil, H; Morrison, D; Swenson, C; Christensen, AB;

Published by: Published on:

YEAR: 2003 DOI:

Studies on the coupling between the neutral winds and the ionosphere at low latitudes

Talaat, ER; DeMajistre, R; Kil, H; Yee, JH; Paxton, L; Azeem, SM; Crowley, G; Christensen, A; Roble, RG;

Published by: Published on:

YEAR: 2003 DOI:

Retrieval of thermospheric temperature and N2, O, and O2 concentrations from GUVI limb scans

Meier, RR; Strickland, DJ; Picone, JM; Christensen, AB; Paxton, LJ; Morrison, D; Kil, H; Bishop, J; Drob, D; Craven, JD; , others;

Published by: Published on:

YEAR: 2003 DOI:

Space Weather in the ITM: The May-June 2003 Storm and NASA TIMED/GUVI Observations and TIMEGCM Model Results

Paxton, LJ; Zhang, Y; Crowley, G; DeMajistre, R; Kil, H; Kusterer, T; Morrison, D; Wolven, B; Meng, C; Christensen, AB; , others;

Published by: Published on:

YEAR: 2003 DOI:

FUV Spectroscopy of the Dayglow and Aurora from the TIMED/GUVI Sensor

Wolven, B; Morrison, D; Paxton, L; Zhang, Y; Kil, H; Meng, CI; Christensen, AB;

Published by: Published on:

YEAR: 2003 DOI:

Low-Latitude Ionospheric Plasma Depletions: Imaging, Modeling, and Interpretation Using Space-Based Ultraviolet Measurements

Comberiate, JM; Kamalabadi, F; Paxton, L; Kil, H;

Published by: Published on:

YEAR: 2003 DOI:

Detection and Mapping of Plasma Bubbles With the Global Ultraviolet Imager

Kamalabadi, F; Comberiate, J; Paxton, L; Kil, H;

Published by: Published on:

YEAR: 2003 DOI:

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

Kelley, Michael; Makela, Jonathan; Paxton, Larry; Kamalabadi, Farzad; Comberiate, Joseph; Kil, Hyosub;

Published by: Geophysical Research Letters Published on:

YEAR: 2003 DOI:

Initial observations with the Global Ultraviolet Imager (GUVI) in the NASA TIMED satellite mission

The Global Ultraviolet Imager (GUVI) instrument carried aboard the NASA TIMED satellite measures the spectral radiance of the Earth\textquoterights far ultraviolet airglow in the spectral region from 120 to 180 nm using a cross-track scanning spectrometer design. Continuous operation of the instrument provides images of the Earth\textquoterights disk and limb in five selectable spectral bands. Also, spectra at fixed scanning mirror position can be obtained. Initial results demonstrate the quantitative functionality of the instrument for studies of the Earth\textquoterights dayglow, aurora, and ionosphere. Moreover, through forward modeling, the abundance of the major constituents of the thermosphere, O, N₂, and O₂\ and thermospheric temperatures can be retrieved from observations of the limb radiance. Variations of the column O/N₂\ ratio can be deduced from sunlit disk observations. In regions of auroral precipitation not only can the aurora regions be geographically located and the auroral boundaries identified, but also the energy flux Q, the characteristic energy E_o, and a parameter f_o\ that scales the abundance of neutral atomic oxygen can be derived. Radiance due to radiative recombination in the ionospheric F region is evident from both dayside and nightside observations of the Earth\textquoterights limb and disk, respectively. Regions of depleted F-region electron density are evident in the tropical Appleton anomaly regions, associated with so-called ionospheric \textquotedblleftbubbles.\textquotedblright Access to the GUVI data is provided through the GUVI website\ www.timed.jhuapl.edu\guvi.

Christensen, AB; Paxton, LJ; Avery, S; Craven, J; Crowley, G; Humm, DC; Kil, H; Meier, RR; Meng, C-I; Morrison, D; , others;

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

YEAR: 2003 DOI: 10.1029/2003JA009918

airglow; AURORA; ultraviolet; imaging; satellite; atmosphere

Negative ionospheric storms seen by the IMAGE FUV instrument

Data from the IMAGE SI-13 instrument are used to study depletions in the OI 135.6 nm dayglow intensity due to two magnetic storms observed on 8 June and 15 July 2000. Results show that the SI-13 instrument is sensitive to changes in the 135.6 nm dayglow caused by depletion of the O/N₂\ column density ratio. It is found that depletion levels in the SI-13 images are weaker than those in the true O/N₂\ values or electron density parameters, such as NmF2 (peak F2 electron density) due to the N₂\ LBH contribution in the SI-13 intensities. A depletion of -20\% (8 June 2000) and -50\% (15 July 2000) in the SI-13 intensities corresponds to -50\% and -90\% reductions in NmF2, respectively. AURIC simulations indicate that -67\% is the maximum depletion level that can be seen in the SI-13 intensities. The Millstone radar, digisonde and DMSP observations reveal that the electron density depletion extended from the low F-layer altitudes up to 840 km. Owing to the prevailing thermospheric circulation pattern, the depletions cover a wide area (at least 1/8 Earth surface) over the Northern Hemisphere for both of the cases. A deep depletion was always seen first in the morning side and then at later local times. The atmosphere took about 12 hours (8 June case) and more than 24 hours (15 July case) to recover. The results from the SI-13 images are in a good agreement with digisonde, radar, and DMSP observations. The depletion in the SI-13 intensity can be explained by the Joule and particle heating in the high-latitude regions. The heating has two effects: (1) The heated air is nitrogen-rich/oxygen-depleted and (2) a wind surge created by the heating in the night side moves the oxygen-deplete air upward and transports it to lower latitudes together with the neutral wind. Corotation with the Earth brings the oxygen-depleted air to the dayside.

Zhang, Y.; Paxton, L.J.; Kil, H.; Meng, C.-I.; Mende, S.~B.; Frey, H.~U.; Immel, T.~J.;

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

YEAR: 2003 DOI: 10.1029/2002JA009797

Atmospheric Composition and Structure: Airglow and aurora; Atmospheric Composition and Structure: Thermosphere-composition and chemistry; atmospheric composition change; depletion of OI 135.6 nm dayglow; Ionosphere: Ionospheric disturbances; Ionosphere: Plasma temperature and density; Magnetospheric Physics: Storms and substorms; negative ionospheric storms

Optical Signature of Polar Cusp During Southward IMF Bz Observed by TIMED/GUVI and DMSP

The GUVI instrument on board the TIMED satellite provides unique multi-wavelength observations of polar region emissions. In this study we focus on the identification of the polar cusp region during southward IMF conditions. Using simultaneous DMSP particle observations, the optical signatures and dynamics of the polar cusp region are investigated. We will address which of the five GUVI wavelengths can best be used for optical identification of the cusp precipitation by comparing images of various wavelengths. These new GUVI observations suggest that cusp aurora in the FUV extends over a relatively wide MLT range during a large southward IMF Bz. Characteristics and morphology of the cusp auroras in the FUV will also be discussed.

Zhang, Y.; Meng, C.~I.; Paxton, L.~J.; Morrison, D.; Wolven, B.; Kil, H.; Newell, P.; Wing, S.; Christensen, A.~B.;

Published by: AGU Fall Meeting Abstracts Published on:

YEAR: 2003 DOI:

2455 Particle precipitation; 2704 Auroral phenomena (2407); 2724 Magnetopause; and boundary layers; cusp

2002

Characterization of Low Latitude Ionospheric Plasma Depletions Using Space-Based Ultraviolet Imaging

Comberiate, JM; Kamalabadi, F; Paxton, LJ; Kil, H;

Published by: Published on:

YEAR: 2002 DOI:

TIMED/GUVI observations of the equatorial anomaly: first-principles model comparisons

Straus, P; Crowley, G; Paxton, L; Christensen, A; Morisson, D; Kil, H;

Published by: Published on: