TITLE:
  Kinetic and spectroscopic requirements for the measurement of
  mesospheric water vapor at 6.8 mu under non-LTE conditions

AUTHORS:
  Mlynczak, M. G., D. K. Zhou, M. Lopez-Puertas, and G. Zaragoza

REFERENCE:
  Geophy. Res. Lett., 26, 63-66, 1999 

ABSTRACT:
We present accuracy requirements for specific kinetic parameters used to 
calculate the populations and vibrational temperatures of the H2O(010) and 
H2O(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 orbitting satellites. Improvement in the rate constants which 
describe vibration-to-vibration exchange between the H2O(010) and O2(1) 
states is required in addition to improved specification of the rate of the 
quenching of O2(1) by atomic oxygen (O). It is also necessary to more 
accurately determine the yield of vibrationally excited O2(1) resulting from 
ozone photolysis. A contemporary measurement of the rate of quenching of 
H2O(010) by N2 and O2 is also desirable. These rates are either highly 
uncertain of have never before been measured at atmospheric temperatures. 
The suggested improvements are necessary for the interpretation of water 
vapor emission measurements at 6.8 mu 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.