Bibliography

Next Generation Instrumentation in Solar and Space Physics: Critical Measurements from Low-Cost Missions/Platforms I

DeLuca, Edward; Paxton, Larry; Schwadron, Nathan; Millan, Robyn;

Published by:       Published on:

YEAR: 2014     DOI:

Interannual Variability of the Atmospheric Tides over South Pole from a Decade of Meteor Wind Observations

Paxton, LJ; Schaefer, RK; Zhang, Y; Bust, GS; Kil, H;

Published by:       Published on:

YEAR: 2014     DOI:

The Cost of Climate Disruption: Rising Ozone Concentration \& Public Health

Strong, Shadrian; Novak, Alexandra; Paxton, Larry;

Published by:       Published on:

YEAR: 2014     DOI:

Quantification of upper thermosphere composition and its dynamic charge exchange coupling to the mid-latitude topside ionosphere

Waldrop, Lara; Paxton, Larry; Aponte, Nestor; Gonzalez, Sixto;

Published by:       Published on:

YEAR: 2014     DOI:

A comprehensive empirical model of the ionospheric conductivity derived from SSUSI/GUVI, SuperMAG and SuperDARN data.

Gjerloev, Jesper; Schaefer, Robert; Paxton, Larry; Zhang, Yongliang;

Published by:       Published on:

YEAR: 2014     DOI:

FUSION++: A New Data Assimilative Model for Electron Density Forecasting

Bust, Gary; Comberiate, Joseph; Paxton, Larry; Kelly, Mike; Datta-Barua, Seebany;

Published by:       Published on:

YEAR: 2014     DOI:

Understanding Hemispheric Asymmetry and Space Weather I Posters

Paxton, Larry; Newell, Patrick; Stromme, Anja; Ridley, Aaron;

Published by:       Published on:

YEAR: 2014     DOI:

Ionospheric Data Assimilation from a Data Provider's Perspective

Schaefer, Robert; Paxton, Larry; Bust, G; Zhang, Yongliang; Romeo, Giuseppe; Comberiate, Joseph; Gelinas, Lynette;

Published by:       Published on:

YEAR: 2014     DOI:

EMIC Wave Induced Radiation Belt Losses and Proton Aurora

Erlandson, Robert; Paxton, Larry; Zhang, Yongliang; Schaefer, Robert;

Published by:       Published on:

YEAR: 2014     DOI:

Magnetospheric Physics General Contributributions Posters

Millan, Robyn; Paxton, Larry; Richardson, Ian;

Published by:       Published on:

YEAR: 2014     DOI:

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:

YEAR: 2014     DOI:

Hydroepidemiology: Bridging Hydrology and Climate with Human Health II Posters

Jutla, Antarpreet; Illangasekare, Tissa; Akanda, Ali; Paxton, Larry;

Published by:       Published on:

YEAR: 2014     DOI:

Specification of Auroral Ionospheric Conductances Using SSUSI and GUVI UV Imagery

Paxton, Larry; Zhang, Yongliang; Schaefer, Robert; Weiss, Michele; Miller, Ethan;

Published by:       Published on:

YEAR: 2014     DOI:

Operational Space Weather Needs-Perspectives from SEASONS 2014

Comberiate, Joseph; Kelly, MA; Paxton, Larry; Schaefer, Robert; Bust, Gary; Sotirelis, Thomas; Fox, Nicola;

Published by:       Published on:

YEAR: 2014     DOI:

Thermospheric Composition Variability and Its Coupling to the Ionosphere I

Zhang, Yongliang; Paxton, Larry; Fuller-Rowell, Timothy; Knipp, Delores;

Published by:       Published on:

YEAR: 2014     DOI:

OVATION Prime-2013: Solar Wind Driven Precipitation Model Extended to Higher Geomagnetic Activity Levels

Newell, Patrick; Liou, Kan; Zhang, Yongliang; Sotirelis, Thomas; Paxton, Larry; Mitchell, Elizabeth;

Published by:       Published on:

YEAR: 2014     DOI:

Transequatorial Propagation and Depletion Precursors

Miller, Ethan; Bust, Gary; Kaeppler, Stephen; Frissell, Nathaniel; Paxton, Larry;

Published by:       Published on:

YEAR: 2014     DOI:

Accomplishing Transformative Research in a Challenging Fiscal Environment

Mitchell, Elizabeth; Paxton, Larry; Bust, G;

Published by:       Published on:

YEAR: 2014     DOI:

Progress toward forecasting of space weather effects on UHF SATCOM after Operation Anaconda

Kelly, Michael; Comberiate, Joseph; Miller, Ethan; Paxton, Larry;

Published by: Space Weather      Published on:

YEAR: 2014     DOI:

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:

YEAR: 2014     DOI:

The MSX/UVISI Stellar Occultation Experiments: Proof-of-Concept Demonstration of a New Approach to Remote Sensing of Earth’s Atmosphere

Vervack, Ronald; Yee, Jeng-Hwa; Swartz, William; DeMajistre, Robert; Paxton, Larry;

Published by: JOHNS HOPKINS APL TECHNICAL DIGEST      Published on:

YEAR: 2014     DOI:

Establishing the connection between crowd-sourced data and decision makers

Paxton, Larry; Swartz, W; Strong, Shadrian; Nix, MG; Schaefer, Robert; Weiss, Michele;

Published by:       Published on:

YEAR: 2014     DOI:

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:

YEAR: 2014     DOI:

Storm-Time Behaviors of the Thermospheric O/N2 and NO Variations

Zhang, Yongliang; Paxton, Larry; Morrison, Daniel; Kil, Hyosub; Marsh, Daniel;

Published by:       Published on:

YEAR: 2014     DOI:

Updated Global Data from the Guvi Instrument: New Products, Updated Calibration, and a New Web Interface

Schaefer, Robert; Paxton, Larry; Romeo, Giuseppe; Wolven, Brian; Zhang, Yongliang; Comberiate, Joseph;

Published by:       Published on:

YEAR: 2014     DOI:

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:

YEAR: 2014     DOI:

Near real-time global auroral observations and their application to IRI

Zhang, Yongliang; Paxton, Larry; Bilitza, Dieter;

Published by: 40th COSPAR Scientific Assembly      Published on:

YEAR: 2014     DOI:

Lyman $\alpha$ airglow emission: Implications for atomic hydrogen geocorona variability with solar cycle

Satellite-based measurements of geocoronal Lyman α (Ly_α) emission at 121.6 nm, created through multiple scattering of solar Ly_αphotons by atomic hydrogen, offer a valuable means of inferring the hydrogen abundance, [H], in the terrestrial thermosphere and exosphere on a global, long-term basis. We present initial results from an analysis of Ly_α radiance measurements acquired across the Earth\textquoterights limb from 2002 to 2007 by the Global UltraViolet Imager (GUVI) onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft. This data spans nearly half of a solar cycle, and both the absolute Ly_α radiance as well as its relative variation across the limb are shown to exhibit a significant dependence on solar activity. We describe sensitivities of a forward radiative transport (RT) model to key parameters governing the [H] distribution in order to assess implications for [H] estimation from the GUVI limb scan data throughout the solar cycle. Based on data-model comparisons, we conclude that the observed solar cycle variability is indicative of a decrease in dayside H density at the exobase with increasing solar activity. These results, along with additional forward RT modeling based on NRLMSISE-00 model specification of [H], are also used to assess contemporary semiempirical model accuracy.

Waldrop, L.; Paxton, L.;

Published by: Journal of Geophysical Research: Space Physics      Published on: Jan-09-2013

YEAR: 2013     DOI: 10.1002/jgra.50496

atmospheric escape; hydrogen geocorona; radiative transport

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\ ratio contamination by the ionosphere using the GUVI observations and model ionosphere acquired from 31 August to 2 September 2002. During this period, the local time of the GUVI observation was near 1500 and the average\ Kp\ index was 2\textdegree. The 135.6 nm emission originated from the ionosphere is estimated using the electron density profiles provided by the Utah State University-Global Assimilation of Ionospheric Measurements model. Our results show that the 135.6 nm emission originated from the equatorial ionization anomaly (EIA) contributes 5 ~ 10\% to the total 135.6 nm intensity and O/N₂\ ratio. The EIA feature and longitudinal wave patterns in the GUVI 135.6 nm intensity maps are identified above an altitude of 300 km and show a good agreement with those in the\ F\ region plasma density. However, the EIA feature and longitudinal wave patterns do not appear in the GUVI 135.6 nm intensity maps below an altitude of 300 km and in the GUVI N₂\ Lyman-Birge-Hopfield band intensity maps in any altitude. These observations indicate that the longitudinal wave patterns in the GUVI O/N₂\ ratio represent the ionospheric phenomenon.

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

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 emission arises from two sources: photoelectron impact excitation of neutral atomic oxygen and the radiative recombination of O⁺ with electrons. We estimate the O/N₂ ratio disturbance associated with the O⁺ density enhancement during geomagnetic storms through the case study of the storms on 20 November 2003 and 8 November 2004. The OI 135.6 nm emission enhancement originating from the ionosphere is derived using the Utah State University Global Assimilation of Ionospheric Measurements model ionosphere. Our results show that the O/N₂ ratio increase from the equator to middle latitudes during the storm periods is primarily associated with thermospheric neutral composition disturbances. However, the contribution of the OI 135.6 nm emission originating from the ionosphere to the storm time O/N₂ ratio increase is substantial in the northern low-middle latitude regions where severe plasma density enhancements occur during the main phase of the storms. Therefore, the ionospheric contribution should be considered for an accurate assessment of the storm time O/N₂ ratio increase at low-middle latitudes during these large storm events.

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

geomagnetic storm; GUVI O/N2 ratio; ionospheric effect

System and method for tomographic retrieval of parameter profile from traveling path

Paxton, Larry; Comberiate, Joseph; Kelly, Michael;

Published by:       Published on: 11

YEAR: 2013     DOI:

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 electrons in the nightside ionosphere. The GUVI data show that the MLA occurred in all seasons under geomagnetically quiet condition (mean Kp ~ 1.0) and during periods of low solar activity. Hemispheric symmetric MLA were observed during equinox. During solstice, the MLA were seen only in the winter hemisphere. The MLA were more frequently observed at local times between ~21:00 and 02:00 on nightside. They were rarely observed at local times between 03:00 and sun rise. The MLA were observed with an occurrence frequency of ~75\% of the time. Coincident GPS total electron current data confirm that the MLA were due to enhanced ionospheric electron density. GUVI 135.6 nm limb data further show that the altitude of the MLA is higher than that of the equatorial arcs created by the equatorial ionization anomaly or fountain effect. The appearance of the MLA at higher altitude than the equatorial arcs supports the idea that the creation of the MLA is associated with the uplift of the ionosphere by the equatorward neutral wind.

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

GUVI; Ionosphere; UV imager

Statistical comparison of isolated and non-isolated auroral substorms

The present study compares isolated and non-isolated substorms in terms of their global morphology and energy deposition. The analysis is based on a list of geomagnetic substorm onsets identified with magnetometer data from SuperMAG and published previously by Newell and Gjerlove (2011a). Isolated substorms are defined as those with separation of two consecutive onsets no less than 3 h. The auroral data are obtained from the global ultraviolet imager (GUVI) on board the TIMED satellite and are rebinned into typical magnetic latitude-magnetic local time maps. The auroral maps are then averaged in 1 min intervals to show the dynamic change of the aurora. The three phases of the substorm are clearly demonstrated in both isolated and non-isolated substorms. However, there are noticeable differences between the two types of substorms: (1) While the nighttime auroral power for both types of substorms slightly increases in the growth phase, isolated (non-isolated) substorms are associated with smaller (greater) nighttime auroral power. (2) In the expansion phase, isolated substorms are associated with greater and more explosive energy release than non-isolated substorms. (3) The time for the recovery phase is ~2 times longer for isolated than for non-isolated substorms. (4) The winter-to-summer auroral power ratio is approximately constant throughout the three substorm phases and the ratio is larger for isolated (~30\%) than that for non-isolated (~10\%) substorms. It is also found that the polar cap area increases during the growth phase until ~10 min prior to the magnetic substorm onset and decreases rapidly thereafter. The decrease is found to result from the closure of the nightside polar cap associated with substorm expansion. It is found that the observed differences between the two types of substorms simply reflect the differences in the solar wind and EUV drivers. Thus, we conclude that there is no intrinsic difference between isolated and non-isolated substorms in terms of auroral energy release and subsequent auroral power decay.

Liou, Kan; Newell, Patrick; Zhang, Yong-Liang; Paxton, Larry;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2013

YEAR: 2013     DOI: 10.1002/jgra.50218

auroral power; auroral substorm; GUVI; SuperMAG; TIMED

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)

Empirical relationship between electron precipitation and far-ultraviolet auroral emissions from DMSP observations

Auroral emissions observed in the far-ultraviolet wavelength range are compared with measurements of the coincident precipitating electrons and ions that produce the emissions in a large-scale correlative study. The auroral emissions and particle precipitation are observed with the Special Sensor Ultraviolet Spectrographic Imager and SSJ5 detectors, respectively, both onboard the DMSP F16 satellite. Coincident observations along the same magnetic field line in the Northern Hemisphere are assembled from two consecutive winters (during 2005\textendash2007). A numerical fit to 27,922 coincident observations provides an empirical relationship between the electron energy flux and the intensity of Lyman-Birge-Hopfield long emissions, J_Ee = 4.90 .10⁸ (eV s^\textendash1 sr^\textendash1 cm^\textendash2)/R I_LBHL (valid in the absence of significant ion fluxes: J_Ee \> 10 J_Eion). A fit to 1308 coincident observations provides the relationship between the average electron energy and the Lyman-Birge-Hopfield short to Lyman-Birge-Hopfield long emission ratio, \<E_e \> = 19.6 keV exp(\textendash2.34 I_LBHS / I_LBHL) (valid from 3 to 19.6 keV). These resulting empirical relationships permit the energy flux and average energy of precipitating electrons to be inferred from far-ultraviolet imagery, in the absence of significant ion precipitation.

Sotirelis, Thomas; Korth, Haje; Hsieh, Syau-Yun; Zhang, Yongliang; Morrison, Daniel; Paxton, Larry;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2013

YEAR: 2013     DOI: 10.1002/jgra.50157

DMSP; electron aurora; electron precipitation; FUV Aurora

The quiet nighttime low-latitude ionosphere as observed by TIMED/GUVI

In this paper, we examine the nighttime ionosphere climatology structure in the low latitude region and discrepancies between Global Ultraviolet Imager (GUVI) observations and the IRI model predictions using (1) the magnetic zonal mean of electron number density as a function of altitude and magnetic latitude, (2) vertical electron density profiles at various levels of F10.7 index, (3) nighttime descent and magnitude decrease of the ionosphere, (4) point-to-point comparisons of F-peak height (hmF2) and density (NmF2), and (5) the magnetic longitudinal variations of hmF2 and NmF2. The data collected from the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) mission since its launch in December 2001 have provided great opportunities for many scientific investigations of the ionosphere. In this analysis, we investigate the climatology of the nighttime low-latitude ionosphere under low geomagnetic activity (kp\ ⩽\ 4) using the electron density profiles inferred from the airglow measurements obtained by the GUVI aboard the TIMED spacecraft and compared with the results obtained from IRI (International Reference Ionosphere) model-2001. The observed climatology is an essential tool for further understanding the electrodynamics in the low-latitude region and improving the model\textquoterights prediction capability. The time range of the GUVI data used in this study is from 2002 (day 053) to 2006 (day 304), and the IRI model predictions were produced at every GUVI location. The ionosphere observed is generally of greater density than what IRI predicts throughout the night for all four seasons for low and moderate solar activity while the model over-predicts the electron density near the F-region peak at high solar activity before midnight. Observations show that the height of the F-region peak has a steep descent from dusk to midnight and near midnight the height of layer is insensitive to solar conditions, significantly different than what is predicted by IRI. Longitudinal features shown in GUVI data are present in the low-latitude ionosphere after sunset and continue through to midnight after which the low-latitude ionosphere is largely zonally symmetric.

Talaat, E.R.; Yee, J.-H.; Hsieh, S.-Y.; Paxton, L.J.; DeMajistre, R.; Christensen, A.B.; Bilitza, D.;

Published by: Advances in Space Research      Published on: 02/2013

YEAR: 2013     DOI: 10.1016/j.asr.2012.11.012

Electron density; GUVI; Ionosphere; IRI; TIMED

Multi-Instrument Observations at High Latitudes

Miller, E; Paxton, L; Schaefer, RK; Weiss, M; Wolven, BC; Zhang, Y;

Published by:       Published on:

YEAR: 2013     DOI:

Observing the mid-and low-latitude ionosphere-global UV remote sensing

Paxton, LJ; Kil, H; Miller, ES; Comberiate, J; Schaefer, RK; Zhang, Y; Team, GUVI; , others;

Published by:       Published on:

YEAR: 2013     DOI:

Observing the Edge of the Inner Radiation Belt: the South Atlantic Anomaly Seen with Photometers in Low Earth Orbit

Schaefer, RK; Wolven, BC; Paxton, L; Romeo, G; Selby, C; Hsieh, SW;

Published by:       Published on:

YEAR: 2013     DOI:

Ring current and polar rain auroras

Zhang, Y; Paxton, L; Kil, H;

Published by:       Published on:

YEAR: 2013     DOI:

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:

YEAR: 2013     DOI:

Evidence of auroral oval TEC enhancement and simultaneous plasma patch break-off events in the Arctic and Antarctic ionosphere during the initial phase of a geomagnetic storm event at equinox, 26 September 2011

Kinrade, Joe; Mitchell, Cathryn; Paxton, Larry; Bust, Gary;

Published by:       Published on:

YEAR: 2013     DOI:

Future Needs for Remote Sensing in Heliophysics: Photonic Observations

DeLuca, EE; Paxton, L;

Published by:       Published on:

YEAR: 2013     DOI:

The Mesoscale Ionospheric Simulation Testbed (MIST) Regional Data Assimilation Model

Comberiate, J; Kelly, MA; Miller, E; Paxton, L;

Published by:       Published on:

YEAR: 2013     DOI:

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:

YEAR: 2013     DOI:

UV Remote Sensing Data Products-Turning Data Into Knowledge

Weiss, M; Paxton, L; Schaefer, RK; Comberiate, J; Hsieh, SW; Romeo, G; Wolven, BC; Zhang, Y;

Published by:       Published on:

YEAR: 2013     DOI:

SSUSI: A Newly Available Resource for the Upper Atmosphere Community to Study the Global Response of the Coupled Ionosphere Thermosphere System

Paxton, L; Schaefer, RK; Weiss, M; Wolven, BC; Zhang, Y; Miller, E; Bust, GS; Romeo, G;

Published by:       Published on:

YEAR: 2013     DOI:

Ultraviolet Observations of the Equatorial Ionosphere at the Terminator

Miller, ES; Comberiate, J; Paxton, LJ;

Published by:       Published on:

YEAR: 2013     DOI:

Behaviors of the ionospheric and thermospheric disturbances during geomagnetic storms

Kil, H; Lee, W; Zhang, Y; Paxton, LJ;

Published by:       Published on:

YEAR: 2013     DOI:

SSUSI Aurora Forecast Model

A new capability has been developed at JHU/APL for forecasting the global aurora quantities based on the DMSP SSUSI data and the TIMED/GUVI Global Aurora Model. The SSUSI Aurora Forecast Model predicts the electron energy flux, mean energy, and equatorward boundary in the auroral oval for up to 1 day or 15 DMSP orbits in advance. In our presentation, we will demonstrate this newly implemented capability and its results. The future improvement plan will be discussed too.

Hsieh, S.~W.; Zhang, Y.; Schaefer, R.~K.; Romeo, G.; Paxton, L.;

Published by: AGU Fall Meeting Abstracts      Published on:

YEAR: 2013     DOI:

Auroral phenomena; forecasting; Ionosphere/magnetosphere interactions; Modeling and forecasting