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Observations of atomic deuterium in the mesosphere from ATLAS 1 with ALAE Instrument
Author(s) -
Bertaux JeanLoup,
Quémerais Eric,
Goutail Florence,
Kockarts Gaston,
Sandel Bill
Publication year - 1993
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/93gl00077
Subject(s) - exosphere , thermosphere , solar zenith angle , mesosphere , zenith , physics , deuterium , atomic physics , atmospheric sciences , ionosphere , geophysics , stratosphere , optics , ion , quantum mechanics
During the first ATLAS mission, the ALAE Lyman α spectrophotometer collected various measurements of hydrogen and deuterium atoms, from the mesosphere, the thermosphere, the exosphere and the interplanetary medium. In this paper is presented a preliminary analysis of some observations of atomic deuterium, which Lyman α emission is excited by resonance scattering of solar photons. Nadir measurements along the sunlit Earth part of the orbit show that the emission changes as a function of solar zenith angle. Comparison with a simple model shows that, from the shuttle altitude of 300 km and at low solar zenith angles, the line‐of‐sight probes atomic deuterium down to 80 km of altitude (where O 2 absorption is complete), whereas at angles from 60° to 90°, the mesospheric part of the emission progressively vanishes. Then, the remaining emission mainly consist of the thermospheric part ( z ≥ 100 km). This type of observations provides a sounding of atomic deuterium at its peak production and concentration, and D atoms can be used as a proxy to H atoms (which cannot be observed from a satellite) in this particularly active region of the mesosphere.