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Found 66 entries in the Bibliography.
Showing entries from 1 through 50
2021 |
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: |
Schaefer, Robert; Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Romeo, Giuseppe; Wolven, Brian; Yonker, Justin; Published by: Published on: |
2020 |
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 |
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 |
Kil, Hyosub; Schaefer, Robert; Paxton, Larry; Jee, Geonhwa; Published by: Geophysical Research Letters Published on: |
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: |
The Origin of Bubble-like Structures in Midlatitudes during Geomagnetic Storms Kil, Hyosub; Paxton, Larry; Lee, Woo; Published by: Published on: |
2019 |
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 |
Plasma blobs associated with medium-scale traveling ionospheric disturbances Kil, Hyosub; Paxton, Larry; Jee, Geonhwa; Nikoukar, Romina; Published by: Geophysical Research Letters Published on: |
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: |
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: |
2018 |
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 |
2017 |
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 |
2015 |
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 |
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 |
2014 |
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 |
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 |
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 |
2013 |
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 |
[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 |
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 |
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; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2013 YEAR: 2013   DOI: 10.1002/jgra.50327 |
Multi-Periodic Auroral and Thermospheric Variations in 2006 Zhang, Yongliang; Paxton, L.; Kil, Hyosub; Published by: Terrestrial, Atmospheric and Oceanic Sciences Published on: 04/2013 YEAR: 2013   DOI: 10.3319/TAO.2012.09.20.01(SEC) |
2012 |
Park, Jaeheung; Lühra, Hermann; Jakowski, Norbert; Gerzen, Tatjana; Kil, Hyosub; Jee, Geonhwa; Xiong, Chao; Min, Kyoung; Noja, Max; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-05-2012 YEAR: 2012   DOI: 10.1016/j.jastp.2012.03.009 |
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 |
2011 |
Published by: Geophysical Research Letters Published on: Jan-10-2011 YEAR: 2011   DOI: 10.1029/2011GL049432 |
Nightside polar rain aurora boundary gap and its applications for magnetotail reconnection Zhang, Yongliang; Paxton, L.; Kil, Hyosub; Published by: Journal of Geophysical Research Published on: Jan-01-2011 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.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 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.; Published by: Journal of Geophysical Research Published on: Jan-01-2011 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; Published by: Journal of Geophysical Research Published on: Jan-01-2011 YEAR: 2011   DOI: 10.1029/2011JA016750 |
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 ... Published by: Published on: YEAR: 2011   DOI: 10.1007/978-94-007-0326-1_26 |
2010 |
Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-03-2010 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.; Published by: Journal of Geophysical Research Published on: Jan-01-2010 YEAR: 2010   DOI: 10.1029/2010JA015979 |
2009 |
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; Published by: Journal of Geophysical Research Published on: 11/2009 YEAR: 2009   DOI: 10.1029/2009JA014369 Equatorial ionosphere; plasma depletion shell; zonal shear flow |
2008 |
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.; Published by: Advances in Space Research Published on: Jan-08-2008 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.; Published by: Journal of Geophysical Research Published on: Jan-01-2008 YEAR: 2008   DOI: 10.1029/2008JA013106 |
2007 |
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.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-12-2007 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.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-02-2007 YEAR: 2007   DOI: 10.1016/j.jastp.2006.06.010 |
2006 |
F-region Pedersen conductivity deduced using the TIMED/GUVI limb retrievals Kil, H.; DeMajistre, M.; Paxton, L.; Zhang, Y.; Published by: Annales Geophysicae Published on: Jan-01-2006 YEAR: 2006   DOI: 10.5194/angeo-24-1311-2006 |
Zhang, Y.; Paxton, L.; Kozyra, J.; Kil, H.; Brandt, P.; Published by: Journal of Geophysical Research Published on: Jan-01-2006 YEAR: 2006   DOI: 10.1029/2005JA011152 |
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 ... Published by: Journal of Geophysical Research Published on: 12/2006 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; Published by: Journal of Geophysical Research Published on: 10/2006 YEAR: 2006   DOI: 10.1029/2006JA011743 |
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; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 09/2006 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.; Published by: Published on: |
2005 |
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.; Published by: Journal of Geophysical Research Published on: 09/2005 YEAR: 2005   DOI: 10.1029/2004JA010668 auroral undulation; K-H instability; Magnetic storm; plasma convection |
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; Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012) Published on: YEAR: 2005   DOI: 10.1029/2004JA010707 |
GUVI Observations of storm-time control and coupling of the ionosphere and thermosphere Paxton, L.; Kil, H.; DeMajistre, R.; Zhang, Y.; Published by: special ISEA issue Published on: |
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; Published by: Published on: |
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; Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012) Published on: 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.; Published by: Ann. Geophys., special ISEA Published on: |
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