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Found 215 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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Simultaneous Detection of Signatures of Conjugate Photoelectrons in the Ionosphere and Thermosphere We investigate the impact of conjugate photoelectrons (CPEs) on the topside (∼600 km altitude) ionosphere at low and midlatitudes using measurements of the ion temperature, density, and composition from the first Republic of China satellite during a period of the high to moderate solar activity (March 1999 to June 2004). Elevated ion temperatures and densities are observed in the dark Northern American-Atlantic sector during the December solstice and in the Australian sector during the June solstice. The oxygen ion fractio ... Kil, Hyosub; Paxton, Larry; Schaefer, Robert; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA030121 airglow; conjugate photoelectron; ion density; ion temperature |
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Far ultraviolet (FUV) imaging of the aurora from space provides great insight into the dynamic coupling of the atmosphere, ionosphere, and magnetosphere on global scales. To gain a quantitative understanding of these coupling processes, the global distribution of auroral energy flux is required, but the inversion of FUV emission to derive precipitating auroral particles energy flux is not straightforward. Furthermore, the spatial coverage of FUV imaging from Low Earth Orbit (LEO) altitudes is often insufficient to achieve g ... Li, J.; Matsuo, T.; Kilcommons, L.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029739 |
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Kil, Hyosub; Chang, Hyeyeon; Lee, Woo; Paxton, Larry; Sun, Andrew; Lee, Jiyun; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Hong, Junseok; Kil, Hyosub; Lee, Woo; Kwak, Young-Sil; Choi, Byung-Kyu; Paxton, Larry; Published by: Published on: |
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Increased Sensitivity FUV Spectrographic Imager
Schaefer, RK; Paxton, LJ; Zhang, Y; Kil, H; Liou, K; Published by: Published on: |
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Hemispheric Asymmetry in the Auroral Ionosphere-Thermosphere System
Liou, K; Zhang, Y-L; Paxton, LJ; Kil, H; Schaefer, R; Published by: Published on: |
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Ionospheric Disturbances in Low- and Midlatitudes During the Geomagnetic Storm on 26 August 2018 Plasma density depletions at midlatitudes during geomagnetic storms are often understood in terms of equatorial plasma bubbles (EPBs) due to their morphological similarity. However, our study reports the observations that reveal the generation of plasma depletions at midlatitudes by local sources. During the geomagnetic storm on 26 August 2018, the Defense Meteorological Satellite Program and Swarm satellites detected plasma depletions at midlatitudes in the Asian sector in the absence of EPBs in the equatorial region. This ... Chang, Hyeyeon; Kil, Hyosub; Sun, Andrew; Zhang, Shun-Rong; Lee, Jiyun; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2022 DOI: 10.1029/2021JA029879 |
| 2021 |
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Exploring the Upper Atmosphere In this chapter, we describe how we can understand the state of the upper atmosphere (the ionosphere, thermosphere, and aurora) using optical observations and how one produces a global view of the Earth s upper atmosphere from optical remote sensing, especially using far ultraviolet (FUV) wavelengths, to advance our understanding of the near Earth space environment. We examine the choice of optical signatures, the basic science behind the signatures, and the techniques for observations. Examples of the technique as applied t ... Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Schaefer, Robert; Published by: Published on: YEAR: 2021 DOI: 10.1002/9781119815631.ch23 Earth space environment; far ultraviolet wavelengths; high-latitude regions; optical remote sensing; solar wind; upper atmosphere |
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Lee, Woo; Kil, Hyosub; Paxton, Larry; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Far Ultraviolet Hyperspectral Imager: NASA's TIMED/GUVI and DMSP SSUSI
Paxton, Larry; Zhang, Yongliang; Schaefer, Robert; Kil, Hyosub; Wolven, Brian; Romeo, Giuseppe; Yonker, Justin; Published by: Published on: |
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Signatures of conjugate photoelectrons in the ionosphere and thermosphere
Kil, Hyosub; Paxton, Larry; Schaefer, Robert; Huba, Joseph; Published by: Published on: |
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Exploring the Upper Atmosphere: Using Optical Remote Sensing
Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Schaefer, Robert; Published by: Upper Atmosphere Dynamics and Energetics Published on: |
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Schaefer, Robert; Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Romeo, Giuseppe; Wolven, Brian; Yonker, Justin; Published by: Published on: |
| 2020 |
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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; Published by: Geophysical Research Letters Published on: 01/2020 YEAR: 2020 DOI: 10.1029/2019GL086383 conjugate photoelectron; far ultraviolet emission; thermosphere; remote sensing data |
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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; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2020 YEAR: 2020 DOI: 10.1029/2019JA027270 Electric field; high latitude; Joule heating; particle precipitation |
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Kil, Hyosub; Schaefer, Robert; Paxton, Larry; Jee, Geonhwa; Published by: Geophysical Research Letters Published on: |
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Origin and distribution of daytime electron density irregularities in the low-latitude F region
Kil, Hyosub; Lee, Woo; Paxton, Larry; Published by: Journal of Geophysical Research: Space Physics Published on: |
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The Origin of Bubble-like Structures in Midlatitudes during Geomagnetic Storms
Kil, Hyosub; Paxton, Larry; Lee, Woo; Published by: Published on: |
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This study aims to identify the characteristics of electron density irregularities in the ionosphere and their creation mechanisms. Ionospheric electron density irregularities which are Published by: Published on: |
| 2019 |
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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; Published by: Geophysical Research Letters Published on: 03/2019 YEAR: 2019 DOI: 10.1029/2019GL082026 |
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Addressing O2R with the SSUSI Operational Space Sensor: Lessons Learned
Schaefer, Robert; Paxton, Larry; Romeo, Giuseppe; Kil, Hyosub; Wolven, Brian; Zhang, Yongliang; Published by: Published on: |
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Plasma blobs associated with medium-scale traveling ionospheric disturbances
Kil, Hyosub; Paxton, Larry; Jee, Geonhwa; Nikoukar, Romina; Published by: Geophysical Research Letters Published on: |
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Daytime evolution of equatorial plasma bubbles observed by the first Republic of China satellite
Kil, Hyosub; Paxton, Larry; Lee, Woo; Jee, Geonhwa; Published by: Geophysical Research Letters Published on: |
| 2018 |
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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; Published by: Geophysical Research Letters Published on: 11/2018 YEAR: 2018 DOI: 10.1029/2018GL080286 |
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Kil, Hyosub; Lee, Woo; Paxton, Larry; Published by: 42nd COSPAR Scientific Assembly Published on: |
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The morphology and driver of the tropical ionization trough
Lee, Woo; Kil, Hyosub; Paxton, Larry; Published by: 42nd COSPAR Scientific Assembly Published on: |
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The role of plasma bubbles and traveling ionospheric disturbances in the creation of plasma blobs
Published by: 42nd COSPAR Scientific Assembly Published on: |
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SSUSI and SSUSI-Lite: Providing space situational awareness and support for over 25 years
Paxton, Larry; Schaefer, Robert; Zhang, Yongliang; Kil, Hyosub; Hicks, John; Published by: Johns Hopkins APL Technical Digest Published on: |
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Tropical ionization trough in the ionosphere seen by Swarm-A satellite
Lee, Woo; Kil, Hyosub; Paxton, Larry; Published by: Geophysical Research Letters Published on: |
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The effect of equatorial fountain on the evolution of equatorial plasma bubbles
Published by: Published on: |
| 2017 |
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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; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2017 YEAR: 2017 DOI: 10.1002/jgra.v122.210.1002/2016JA023578 |
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Published by: Geophysical Research Letters Published on: |
| 2016 |
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Climatological aspect of the equatorial ionospheric dynamics seen by TIMED/GUVI
Published by: Published on: |
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Structure and Variability in the Ionosphere using DMSP/SSUSI and TIMED/GUVI Data
Bruntz, Robert; Paxton, Larry; Kil, Hyosub; Schaefer, Robert; Zhang, Yongliang; Miller, Ethan; Published by: Published on: |
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Solar flare impact on FUV based thermospheric O/N2 estimation
Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: |
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Kil, Hyosub; Lee, Woo; Paxton, Larry; Hairston, Marc; Jee, Geonhwa; Published by: Journal of Geophysical Research: Space Physics Published on: |
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NASA Timed Guvi and Dmsp Ssusi Observations of the St. Patricks Day Storm of
Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Mitchell, Elizabeth; Schaefer, Robert; Published by: 41st COSPAR Scientific Assembly Published on: |
| 2015 |
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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 ... Published by: Journal of Astronomy and Space Sciences Published on: 03/2013 YEAR: 2015 DOI: 10.5140/JASS.2015.32.1.13 |
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Remote sensing of Earth's 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.; Published by: Earth and Space Science Published on: 01/2015 YEAR: 2015 DOI: 10.1002/2014EA000035 airglow and aurora; remote sensing; thermosphere: composition and chemistry; thermosphere: energy deposition |
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During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7–17 March 2012 caused geomagnetic storms that strongly Prikryl, P; Ghoddousi-Fard, R; Spogli, L; Mitchell, CN; Li, G; Ning, B; Cilliers, PJ; , Sreeja; Aquino, M; Terkildsen, M; , others; Published by: Published on: YEAR: 2015 DOI: 10.5194/angeo-33-637-2015 |
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Structures in Polar Rain Auroras
Zhang, Yongliang; Paxton, Larry; Kil, Hyosub; Published by: Auroral Dynamics and Space Weather Published on: |
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The morphology of equatorial plasma bubbles-a review
Published by: Journal of Astronomy and Space Sciences Published on: |
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Morphology of the postsunset vortex in the equatorial ionospheric plasma drift
Lee, Woo; Kil, Hyosub; Kwak, Young-Sil; Paxton, Larry; Published by: Geophysical Research Letters Published on: |
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GUVI and SSUSI Observations of the St. Patrick's Day Storms
Paxton, Larry; Schaefer, Robert; Zhang, Yongliang; Bust, Gary; Kil, Hyosub; Published by: Published on: |
| 2014 |
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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.; Published by: Geophysical Research Letters Published on: 08/2014 YEAR: 2014 DOI: 10.1002/2014GL060953 |
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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.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2014 YEAR: 2014 DOI: 10.1016/j.jastp.2014.04.003 geomagnetic storm; Thermospheric nitric oxide; Thermospheric O/N2 ratio |
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Presented is an analysis of the occurrence of postsunset Equatorial Plasma Bubbles (EPBs) detected using a Global Positioning System (GPS) receiver at Vanimo. The three year data set shows that the EPB occurrence maximizes (minimizes) during the equinoxes (solstices), in good agreement with previous findings. The Vanimo ionosonde station is used with the GPS receiver in an analysis of the day-to-day EPB occurrence variability during the 2000 equinox period. A superposed epoch analysis (SEA) reveals that the altitude, and ... Carter, B.; Yizengaw, E.; Retterer, J.; Francis, M.; Terkildsen, M.; Marshall, R.; Norman, R.; Zhang, K.; Published by: Journal of Geophysical Research: Space Physics Published on: 04/2014 YEAR: 2014 DOI: 10.1002/jgra.v119.410.1002/2013JA019570 |
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The thermospheric O/N2 and NO products from TIMED/GUVI The Global Ultraviolet Imager (GUVI) on TIMED satellite detects FUV (~ 110-185nm) emissions from the thermosphere and ionosphere. The major emission features include HI (Lyman α Zhang, Yongliang; Paxton, Larry; Kil, Hyosub; Published by: 40th COSPAR Scientific Assembly Published on: |
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Investigation of the Tidal Signatures in the Thermosphere Using the TIMED/GUVI Data
Kil, Hyosub; Paxton, Larry; Zhang, Yongliang; Kwak, Young-Sil; Lee, Woo; Published by: Published on: |
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Paxton, LJ; Schaefer, RK; Zhang, Y; Bust, GS; Kil, H; Published by: Published on: |