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Found 78 entries in the Bibliography.
Showing entries from 1 through 50
| 2022 |
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Low-latitude plasma blobs above Africa: Exploiting GOLD and multi-satellite in situ measurements Low-latitude plasma blobs are localized density enhancements of electron density that are occasionally observed in the night-time tropical ionosphere. Two-dimensional (2D) imaging of this phenomenon has been rare and frequently restricted to Central/South America, which is densely covered with ground-based airglow imagers and Global Navigation Satellite System (GNSS) receivers. In Africa, on the contrary, no 2D image of a blob has been reported. Here we present two low-latitude blob events above Africa, one in the Northern s ... Park, Jaeheung; Min, Kyoung; Eastes, Richard; Chao, Chi; Kim, Hee-Eun; Lee, Junchan; Sohn, Jongdae; Ryu, Kwangsun; Seo, Hoonkyu; Yoo, Ji-Hyeon; Lee, Seunguk; Woo, Changho; Kim, Eo-Jin; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.05.021 |
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Low-latitude plasma blobs above Africa: Exploiting GOLD and multi-satellite in situ measurements Low-latitude plasma blobs are localized density enhancements of electron density that are occasionally observed in the night-time tropical ionosphere. Two-dimensional (2D) imaging of this phenomenon has been rare and frequently restricted to Central/South America, which is densely covered with ground-based airglow imagers and Global Navigation Satellite System (GNSS) receivers. In Africa, on the contrary, no 2D image of a blob has been reported. Here we present two low-latitude blob events above Africa, one in the Northern s ... Park, Jaeheung; Min, Kyoung; Eastes, Richard; Chao, Chi; Kim, Hee-Eun; Lee, Junchan; Sohn, Jongdae; Ryu, Kwangsun; Seo, Hoonkyu; Yoo, Ji-Hyeon; Lee, Seunguk; Woo, Changho; Kim, Eo-Jin; Published by: Advances in Space Research Published on: may YEAR: 2022 DOI: 10.1016/j.asr.2022.05.021 |
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Disappearance of the Polar Cap Ionosphere During Geomagnetic Storm on 11 May 2019 Multi-instrument data from Jang Bogo Station (JBS) in Antarctica were utilized to study ionospheric responses to the 11 May 2019 moderate geomagnetic storm. These include Vertical Incident Pulsed Ionospheric Radar (VIPIR)/Dynasonde, Fabry-Perot Interferometer (FPI), GPS vertical total electron content (vTEC), and magnetometer. The VIPIR/Dynasonde observed long-lasting (\textgreater11 hr) severe depletion of the electron density in the F-region ionosphere over JBS. During the depletion interval, GPS TEC also correspondingly d ... Kwon, H.-J.; Kim, K.-H.; Jee, G.; Seon, J.; Lee, C.; Ham, Y.-B.; Hong, J.; Kim, E.; Bullett, T.; Auster, H.-U.; Magnes, W.; Kraft, S.; Published by: Space Weather Published on: YEAR: 2022 DOI: 10.1029/2022SW003054 |
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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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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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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 |
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Retrospect and prospect of ionospheric weather observed by FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2 FORMOSAT-3/COSMIC (F3/C) constellation of six micro-satellites was launched into the circular low-earth orbit at 800 km altitude with a 72-degree inclination angle on 15 April 2006 Liu, Tiger; Lin, Charles; Lin, Chi-Yen; Lee, I-Te; Sun, Yang-Yi; Chen, Shih-Ping; Chang, Fu-Yuan; Rajesh, Panthalingal; Hsu, Chih-Ting; Matsuo, Tomoko; , others; Published by: Terrestrial, Atmospheric and Oceanic Sciences Published on: YEAR: 2022 DOI: 10.1007/s44195-022-00019-x |
| 2021 |
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Transpolar Arcs During a Prolonged Radial Interplanetary Magnetic Field Interval Transpolar arcs (TPAs) are believed to predominantly occur under northward interplanetary magnetic field (IMF) conditions with their hemispheric asymmetry controlled by the Sun-Earth (radial) component of the IMF. In this study, we present observations of TPAs that appear in both the northern and southern hemispheres even during a prolonged interval of radially oriented IMF. The Defense Meteorological Satellite Program (DMSP) F16 and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellites observed T ... Park, Jong-Sun; Shi, Quan; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiu-Gang; Degeling, Alexander; Tian, An; Pitkänen, Timo; Zhang, Yongliang; Rae, Jonathan; Hairston, Marc; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2021 DOI: 10.1029/2021JA029197 radial IMF; solar wind-magnetosphere-ionosphere coupling; transpolar arc |
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Lee, Woo; Kil, Hyosub; Paxton, Larry; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2020 |
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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: |
| 2019 |
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Aeronomy: General Contributions I Posters
Nikoukar, Romina; Lee, Christina; MacDonald, Elizabeth; Published by: Published on: |
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The total electron content (TEC) data from Global Ionosphere Maps are used to obtain the tidal modes through two-dimensional Fourier transform in both universal time and LT (local time) frames. In the LT frame, a north-south TEC asymmetry is observed along the longitude, where there is a large displacement of the geomagnetic equator from the geographic equator. The phases of tidal modes lead to a constructive or destructive interference of contributing tidal modes, producing different zonal waves and longitudinal peaked stru ... Tsai, TC; Jhuang, HK; Lee, LC; Ho, YY; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2019 DOI: 10.1029/2019JA026899 |
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Park, Jong-Sun; Shi, Quanqi; Nowada, Motoharu; Shue, Jih-Hong; Kim, Khan-Hyuk; Lee, Dong-Hun; Zong, Qiugang; Degeling, Alexander; Tian, Anmin; Pitkänen, Timo; , others; Published by: 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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Tropical ionization trough in the ionosphere seen by Swarm-A satellite
Lee, Woo; Kil, Hyosub; Paxton, Larry; Published by: Geophysical Research Letters Published on: |
| 2017 |
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The non--storm time corrugated upper thermosphere: What is beyond MSIS? Observations in the recent decade have revealed many thermospheric density corrugations/perturbations under nonstorm conditions (Kp \< 2). They are generally not captured by empirical models like Mass Spectrometer Incoherent Scatter (MSIS) but are operationally important for long-term orbital evolution of Low Earth Orbiting satellites and theoretically for coupling processes in the atmosphere-ionosphere system. We review these density corrugations by classifying them into three types which are driven ... Liu, Huixin; Thayer, Jeff; Zhang, Yongliang; Lee, Woo; Published by: Space Weather Published on: 06/2017 YEAR: 2017 DOI: 10.1002/swe.v15.610.1002/2017SW001618 |
| 2016 |
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The main purpose of this paper is to investigate the effects of rapid assimilation-forecast cycling on the performance of ionospheric data assimilation during geomagnetic storm conditions. An ensemble Kalman filter software developed by the National Center for Atmospheric Research (NCAR), called Data Assimilation Research Testbed, is applied to assimilate ground-based GPS total electron content (TEC) observations into a theoretical numerical model of the thermosphere and ionosphere (NCAR thermosphere-ionosphere-electrodyn ... Chen, C.; Lin, C.; Matsuo, T.; Chen, W.; Lee, I.; Liu, J; Lin, J.; Hsu, C.; Published by: Journal of Geophysical Research: Space Physics Published on: 05/2016 YEAR: 2016 DOI: 10.1002/2015JA021787 |
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Kil, Hyosub; Lee, Woo; Paxton, Larry; Hairston, Marc; Jee, Geonhwa; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2015 |
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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: |
| 2014 |
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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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Schwadron, NA; Moebius, E; Fuselier, SA; McComas, DJ; Funsten, HO; Janzen, P; Reisenfeld, D; Kucharek, H; Lee, MA; Fairchild, K; , others; Published by: The Astrophysical Journal Supplement Series Published on: |
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The role of the postsunset vortex in the creation of turbulence in the bottomside F region
Lee, Woo; Kil, Hyosub; Kwak, Young-Sil; Paxton, Larry; Published by: Published on: |
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The zonal motion of equatorial plasma bubbles relative to the background ionosphere
Kil, Hyosub; Lee, Woo; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry; Milla, Marco; Published by: Journal of Geophysical Research: Space Physics Published on: |
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The zonal motion of equatorial plasma bubbles relative to the background ionosphere
Kil, Hyosub; Lee, Woo; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry; Milla, Marco; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Equatorial broad plasma depletions associated with the enhanced fountain effect
Lee, Woo; Kil, Hyosub; Kwak, Young-Sil; Paxton, Larry; Zhang, Yongliang; Galkin, Ivan; Batista, Inez; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2013 |
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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.; Published by: Journal of Geophysical Research: Space Physics Published on: Jan-02-2013 YEAR: 2013 DOI: 10.1029/2012JA018112 |
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[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; Published by: Journal of Geophysical Research: Space Physics Published on: 12/2013 YEAR: 2013 DOI: 10.1002/2013JA019132 |
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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 ... Published by: Geophysical Research Letters Published on: 07/2014 YEAR: 2013 DOI: 10.1002/grl.50693 |
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The Study of the origin of broad plasma depletions in the equatorial F region
Oh, S; Lee, W; Kil, H; Kwak, Y; Paxton, L; Zhang, Y; Published by: Published on: |
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Drivers of the hemispheric asymmetry in the low-latitude electron density distribution
Kil, H; Kwak, Y; Lee, W; Paxton, L; Zhang, Y; Published by: Published on: |
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Behaviors of the ionospheric and thermospheric disturbances during geomagnetic storms
Kil, H; Lee, W; Zhang, Y; Paxton, LJ; Published by: Published on: |
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The effect of the 135.6 nm emission originated from the ionosphere on the TIMED/GUVI O/N2 ratio
Kil, H; Lee, WK; Shim, J; Paxton, LJ; Zhang, Y; Published by: Journal of Geophysical Research: Space Physics Published on: |
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Lee, Woo; Kil, Hyosub; Paxton, Larry; Zhang, Yongliang; Shim, Ja; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2012 |
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Day-to-day variability of equatorial anomaly in GPS-TEC during low solar activity period
Aggarwal, Malini; Joshi, H.P.; Iyer, K.N.; Kwak, Y.-S.; Lee, J.J.; Chandra, H.; Cho, K.S.; Published by: Advances in Space Research Published on: Jan-06-2012 YEAR: 2012 DOI: 10.1016/j.asr.2012.03.005 |
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Dayside and nightside segments of a polar arc: The particle characteristics
Park, J.; Min, K.; Parks, G.; Zhang, Y.; Lee, J.-J.; Baker, J.; Kim, H.; Hwang, J.; Yumoto, K.; Uozumi, T.; Lee, C.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017323 |
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Dayside and nightside segments of a polar arc: The particle characteristics
Park, J.; Min, K.; Parks, G.; Zhang, Y.; Lee, J.-J.; Baker, J.; Kim, H.; Hwang, J.; Yumoto, K.; Uozumi, T.; Lee, C.; Published by: Journal of Geophysical Research Published on: Jan-01-2012 YEAR: 2012 DOI: 10.1029/2011JA017323 |
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Ionospheric plasma caves under the equatorial ionization anomaly This paper reports the existence of plasma caves, minima in the electron density located at 5\textendash10\textdegree to the magnetic equator, in the bottomside ionosphere based on electron densities simulations from the International Reference Ionosphere (IRI-2007) and clear evidences given by plasma density and drift measurements of the Dynamic Explorer 2 (DE 2) satellite during 1981\textendash1983. The IRI simulations suggest plasma caves as daytime features (08:00\textendash19:00 LT; length of 18,158 km in the longitu ... Lee, I.; Liu, J; Lin, C.; Oyama, K.-I.; Chen, C; Chen, C.; Published by: Journal of Geophysical Research Published on: 11/2012 YEAR: 2012 DOI: 10.1029/2012JA017868 Dynamic Explorer 2; Equatorial ionization anomaly; plasma cave |
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This paper presents our effort to assimilate FORMOSAT-3/COSMIC (F3/C) GPS Occultation Experiment (GOX) observations into the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) by means of ensemble Kalman filtering (EnKF). The F3/C electron density profiles (EDPs) uniformly distributed around the globe which provide an excellent opportunity to monitor the ionospheric electron density structure. The NCAR TIE-GCM simulates the Earth\textquoterights ther ... Lee, I.; Matsuo, T.; Richmond, A.; Liu, J; Wang, W.; Lin, C.; Anderson, J.; Chen, M.; Published by: Journal of Geophysical Research Published on: 10/2012 YEAR: 2012 DOI: 10.1029/2012JA017700 data assimilation; ensemble Kalman filter; FORMOSAT-3/COSMIC; Ionosphere |
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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.; Published by: Journal of Geophysical Research Published on: 05/2012 YEAR: 2012 DOI: 10.1029/2011JA017349 |
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The Source of Tidal Signatures in the TIMED/GUVI O/N2 Ratio
Kil, H; Lee, W; Shim, J; Paxton, LJ; Zhang, Y; Published by: Published on: |
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Persistent longitudinal features in the low-latitude ionosphere
Kil, H; Lee, WK; Kwak, Y-S; Oh, S-J; Paxton, LJ; Zhang, Y; Published by: Journal of Geophysical Research: Space Physics Published on: |
| 2011 |
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FUV spectrum in the polar region during slightly disturbed geomagnetic conditions
Lee, C.; Min, K.; Lee, J.-J.; Hwang, J.; Park, J.; Edelstein, J.; Han, W.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011 DOI: 10.1029/2011JA016898 |
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FUV spectrum in the polar region during slightly disturbed geomagnetic conditions
Lee, C.; Min, K.; Lee, J.-J.; Hwang, J.; Park, J.; Edelstein, J.; Han, W.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011 DOI: 10.1029/2011JA016898 |
| 2010 |
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Liu, J; Lin, C; Lin, C.; Tsai, H.; Solomon, S.; Sun, Y; Lee, I.; Schreiner, W.; Kuo, Y.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2009JA015079 |
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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.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010 DOI: 10.1029/2010JA015979 |
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