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Surface recombination of O and H 2 on meteoric dust as a source of mesospheric water vapor
Author(s) -
Summers Michael E.,
Siskind David E.
Publication year - 1999
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 - 10.1029/1999gl900430
Subject(s) - atmosphere (unit) , water vapor , mesosphere , mixing ratio , atmospheric sciences , altitude (triangle) , meteoric water , surface layer , layer (electronics) , environmental science , astrobiology , physics , meteorology , stratosphere , materials science , nanotechnology , nuclear physics , geometry , mathematics , stable isotope ratio
One of the most provocative recent developments in mesospheric science is the discovery of a narrow layer of water vapor located near 70 km altitude where the H 2 O mixing ratio reaches the highest values observed in the middle atmosphere [ Summers et al. , 1997a]. This layer can only be explained by a local source of H 2 O, which is contrary to conventional gas phase chemistry that predicts net H 2 O destruction in that part of the mesosphere. Although suggestions have been made that this layer is produced by an influx of small comets releasing water in the upper atmosphere, we propose that the reaction O + H 2 → H 2 O on the surface of meteoric dust can account for the observed H 2 O layer. Using a chemical‐transport model we find that the inclusion of this reaction with a reaction probability of ∼0.01 yields a model H 2 O layer with the observed characteristics. We suggest that the key to understanding the origin of the H 2 O layer lies in coincident observations of mesospheric H 2 and H 2 O.