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Found 6 entries in the Bibliography.
Showing entries from 1 through 6
| 2019 |
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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.; YEAR: 2019 DOI: 10.1029/2019JA027057 |
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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 RE be ... Cucho-Padin, Gonzalo; Waldrop, Lara; YEAR: 2019 DOI: 10.1029/2019GL084327 |
| 2018 |
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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; YEAR: 2018 DOI: 10.1029/2018JA025954 |
| 2017 |
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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; YEAR: 2017 DOI: 10.1002/jgra.v122.1010.1002/2017JA024489 |
| 2016 |
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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 ... YEAR: 2016 DOI: 10.1038/ncomms13655 |
| 2013 |
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Lyman α airglow emission: Implications for atomic hydrogen geocorona variability with solar cycle Satellite-based measurements of geocoronal Lyman α (Lyα) emission at 121.6 nm, created through multiple scattering of solar Lyαphotons 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 Lyα radiance measurements acquired across the Earth\textquoterights limb from 2002 to 2007 by the Global UltraV ... YEAR: 2013 DOI: 10.1002/jgra.50496 |
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