Author:
Fahr Hans J.,Nass Uwe,Dutta-Roy Robindro,Zoennchen Jochen H.
Abstract
Abstract. In a most recent paper by Qin and Waldrop (2016), it had been found that the
scale height of hydrogen in the upper exosphere of the Earth, especially
during solar minimum conditions, appears to be surprisingly large. This
indicates that during minimum conditions when exobasic temperatures should be
small, large exospheric H-scale heights predominate. They thus seem to
indicate the presence of a non-thermal hydrogen component in the upper
exosphere. In the following parts of the paper we shall investigate what
fraction of such expected hot hydrogen atoms could have their origin from
protons of the shocked solar wind ahead of the magnetopause converted into
energetic neutral atoms (ENAs) via charge-exchange
processes with normal
atmospheric, i.e., exospheric hydrogen atoms that in the first step evaporate
from the exobase into the magnetosheath plasma region. We shall show that, dependent on the sunward location of the magnetopause,
the density of these types of non-thermal hydrogen atoms (H-ENAs) becomes
progressively comparable with the density of exobasic hydrogen with increasing
altitude. At
low exobasic heights, however, their contribution is negligible. At the end
of this paper, we finally study the question of whether the H-ENA population
could even be understood as a self-consistency phenomenon of the H-ENA
population, especially during solar activity minimum conditions, i.e., H-ENAs
leaving the exosphere being replaced by H-ENAs injected into the exosphere. Keywords. Magnetospheric physics (plasmasphere; solar wind-magnetosphere interactions) – solar physics, astrophysics, and astronomy (energetic particles)
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geology,Astronomy and Astrophysics
Cited by
4 articles.
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