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Kinetic requirements for the measurement of mesospheric water vapor at 6.8 µm under non‐LTE conditions
Author(s) -
Mlynczak Martin G.,
Zhou Daniel K.,
LopezPuertas Manuel,
Zaragoza Guillermo,
Russell James M.
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 - 10.1029/1998gl900232
Subject(s) - water vapor , quenching (fluorescence) , excited state , kinetic energy , ozone , mesosphere , atmosphere (unit) , reaction rate constant , infrared , photodissociation , analytical chemistry (journal) , materials science , environmental science , atmospheric sciences , atomic physics , meteorology , stratosphere , chemistry , photochemistry , physics , environmental chemistry , kinetics , optics , fluorescence , quantum mechanics
We present accuracy requirements for specific kinetic parameters used to calculate the populations and vibrational temperatures of the H 2 O(010) and H 2 O(020) states in the terrestrial mesosphere. The requirements are based on rigorous simulations of the retrieval of mesospheric water vapor profiles from measurements of water vapor infrared emission made by limb scanning instruments on orbiting satellites. Major improvements in the rate constants that describe vibration‐to‐vibration exchange between the H 2 O(010) and O 2 (1) states are required in addition to improved specification of the rate of quenching of O 2 (1) by atomic oxygen (O). It is also necessary to more accurately determine the yield of vibrationally excited O 2 (1) resulting from ozone photolysis. A contemporary measurement of the rate of quenching of H 2 O(010) by N 2 and O 2 is also desirable. These rates are either highly uncertain or have never before been measured at atmospheric temperatures. The suggested improvements are necessary for the interpretation of water vapor emission measurements at 6.8 µm to be made from a new spaceflight experiment in less than 2 years. The approach to retrieving water vapor under non‐LTE conditions is also presented.