GUVI Biblio

Quantifying the Impact of Dynamic Storm-Time Exospheric Density on Plasmaspheric Refilling

As soon as the outer plasmasphere gets eroded during geomagnetic storms, the greatly depleted plasmasphere is replenished by cold, dense plasma from the ionosphere. A strong correlation has been revealed between plasmaspheric refilling rates and ambient densities in the topside ionosphere and exosphere, particularly that of atomic hydrogen (H). Although measurements of H airglow emission at plasmaspheric altitudes exhibit storm-time response, temporally static distributions have typically been assumed in the H density in pla ...

Waldrop, Lara; Cucho-Padin, Gonzalo; site, this; Maruyama, Naomi; site, this;

Published by: Earth and Space Science Open Archive ESSOAr      Published on: jan

YEAR: 2021     DOI: 10.1002/essoar.10505771.1

Atmospheric Sciences; Atmospheric Sciences / Magnetospheric Particles

Understanding the role of exospheric density in the ring current recovery rate

Atomic Hydrogen (H) is the most abundant constituent of the terrestrial exosphere. Its charge exchange interaction with ring current ions (H+ and O+) serves to dissipate magnetospheric energy during geomagnetic storms, resulting in the generation of energetic neutral atoms (ENAs). Determination of ring current ion distributions through modeling depends critically on the specification of the exospheric H density distribution. Furthermore, theoretical studies have demonstrated that ring current recovery rate after the storm on ...

Cucho-Padin, Gonzalo; site, this; Ferradas, Cristian; Waldrop, Lara; Fok, Mei-Ching; site, this;

Published by: Earth and Space Science Open Archive ESSOAr      Published on: jan

YEAR: 2021     DOI: 10.1002/essoar.10505770.1

Atmospheric Sciences; Atmospheric Sciences / Magnetospheric Particles

Quantification of the vertical transport and escape of atomic hydrogen in the terrestrial upper atmosphere

Measurements of the limiting escape rate of atomic hydrogen (H) atoms at Earth, and the relative significance of thermal evaporation and non-thermal escape mechanisms, such as charge exchange and polar wind, have long been lacking. Our recent development of sophisticated radiative transport analysis techniques now enables the reliable interpretation of remotely-sensed measurements of optically-thick H emission, such as those acquired along the Earth\textquoterights limb by the Global Ultraviolet Imager (GUVI) onboard the ...

Joshi, P.P.; Phal, Y.D.; Waldrop, L.S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2019

YEAR: 2019     DOI: 10.1029/2019JA027057

Time-Dependent Response of the Terrestrial Exosphere to a Geomagnetic Storm

Recent observations of significant enhancements in exospheric hydrogen (H) emission in response to geomagnetic storms have been difficult to interpret in terms of the evolution of the underlying global, 3-D exospheric structure. In this letter, we report the first measurement of the timescales and spatial gradients associated with the exospheric response to a geomagnetic storm, which we derive from a novel, time-dependent tomographic analysis of H emission data. We find that global H density at 3 R_E be ...

Cucho-Padin, Gonzalo; Waldrop, Lara;

Published by: Geophysical Research Letters      Published on: 09/2019

YEAR: 2019     DOI: 10.1029/2019GL084327

Nonparametric H Density Estimation Based on Regularized Nonlinear Inversion of the Lyman Alpha Emission in Planetary Atmospheres

Inversion of space-borne remote sensing measurements of the resonantly scattered solar Lyman alpha (121.6-nm) emission in planetary atmospheres is the most promising means of quantifying the H density in a vast volume of space near terrestrial planets. Owing to the highly nonlinear nature of the inverse problem and the lack of sufficient data constraints over the large volume of space where H atoms are present, previous inversion methods relied on physics-based parametric formulations of the H density distributions to gua ...

Qin, Jianqi; Harding, Brian; Waldrop, Lara;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2018

YEAR: 2018     DOI: 10.1029/2018JA025954

Empirical quantification of the vertical transport and escape of atomic hydrogen in the terrestrial upper atmosphere

Waldrop, Lara; Phal, Yamuna; Kerr, Robert; Qin, Jianqi;

Published by:       Published on:

YEAR: 2018     DOI:

Parametric estimation of neutral hydrogen density under charge exchange and quantification of its effect on plasmasphere-ionosphere coupling

Joshi, Pratik; Waldrop, Lara;

Published by:       Published on:

YEAR: 2018     DOI:

Redistribution of H atoms in the upper atmosphere during geomagnetic storms

Geocoronal H emission data acquired by NASA\textquoterights Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission are analyzed to quantify the H density distribution over the entire magnetosphere-ionosphere-thermosphere region in order to investigate the response of the atmospheric system as a whole to geomagnetic storms. It is shown that at low and middle latitudes the H density averaged over storm times in the thermosphere-exosphere transition region decreases by \~30\%, while the H density at exospheric al ...

Qin, Jianqi; Waldrop, Lara; Makela, Jonathan;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2017

YEAR: 2017     DOI: 10.1002/jgra.v122.1010.1002/2017JA024489

Non-thermal hydrogen atoms in the terrestrial upper thermosphere

Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, m ...

Qin, Jianqi; Waldrop, Lara;

Published by: Nature Communications      Published on: 12/2016

YEAR: 2016     DOI: 10.1038/ncomms13655

Thermal structure of the ITM: old challenges and new insights

Waldrop, Lara; Qin, Jianqi;

Published by:       Published on:

YEAR: 2016     DOI:

Climatology of neutral hydrogen in the terrestrial thermosphere

Qin, Jianqi; Waldrop, Lara;

Published by:       Published on:

YEAR: 2016     DOI:

Hydrogen in the Upper Atmosphere II Posters

Paxton, Larry; Waldrop, Lara; Mierkiewicz, Edwin; Mlynczak, Martin;

Published by:       Published on:

YEAR: 2015     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:

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 UltraV ...

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

Global Spatial and Climatological Dependencies of the Hydrogen Geocorona Inferred From TIMED/GUVI Measurements of Lyman $\alpha$ Radiance

Space-based measurements of geocoronal Lyman-α (Ly-α) emission at 121.6 nm, created through multiple scattering of solar Ly-α photons by atomic hydrogen, offer a

Waldrop, LS; Paxton, LJ;

Published by:       Published on:

YEAR: 2010     DOI: