Kinetic requirements for the measurement of mesospheric water vapor at 6.8 µm under non‐LTE conditions

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.

[1]  Martin G. Mlynczak,et al.  Kinetic and spectroscopic requirements for the inference of chemical heating rates and atomic hydrogen densities from OH Meinel band measurements , 1998 .

[2]  F. S. Klein,et al.  Kinetics of the isotope exchange reaction of 18O with NO and O2 at 298 K , 1985 .

[3]  Jane L. Fox,et al.  Structure, luminosity, and dynamics of the Venus thermosphere , 1991 .

[4]  Manuel López-Puertas,et al.  Non‐local thermodynamic equilibrium in H2O 6.9 μm emission as measured by the improved stratospheric and mesospheric sounder , 1998 .

[5]  Martin G. Mlynczak,et al.  Rapid computation of spectrally integrated non-local thermodynamic equilibrium limb emission , 1994 .

[6]  R. R. Conway,et al.  Implications of Satellite OH Observations for Middle Atmospheric H2O and Ozone , 1997 .

[7]  J. Breen,et al.  Vibrational relaxation of O2 in the presence of atomic oxygen , 1973 .

[8]  A. Kutepov,et al.  Non-local thermodynamic equilibrium in CO 2 in the middle atmosphere. I. Input data and populations of the ν 3 mode manifold states , 1998 .

[9]  G. Bingham,et al.  CIRRIS‐1A limb spectral measurements of mesospheric 9.6‐µm airglow and ozone , 1998 .

[10]  Martin G. Mlynczak,et al.  Rapid computation of spectrally integrated non-LTE limb emission , 1994, Optics & Photonics.

[11]  Manuel López-Puertas,et al.  Non-local thermodynamic equilibrium model for H2O 6.3 and 2.7-μm bands in the middle atmosphere , 1995 .

[12]  Martin G. Mlynczak,et al.  An Overview of the SABER Experiment for the TIMED Mission , 1994, Optical Remote Sensing of the Atmosphere.