Technical Note: Evaluation of simultaneous measurements of mesospheric OH, HO<sub>2</sub>, and O<sub>3</sub> under photochemical equilibrium assumption: Statistical approach
Аннотация:Abstract. The Technical Note presents a statistically correct approach to evaluating simultaneous measurements of several atmospheric components under the assumption of photochemical equilibrium. We consider simultaneous measurements of OH, HO2, and O3 at the altitudes of the mesosphere as a specific example and their daytime photochemical equilibrium as an evaluating relationship. A simplified algebraic equation relating local concentrations of these components in the 50–100 km altitude range has been derived. The parameters of the equation are air temperature, air concentration, local zenith angle, and the rates of 9 reactions. We have performed one-year simulation of the mesosphere and lower thermosphere using a 3D chemical-transport model. The simulation shows that the discrepancy between the calculated evolution of the components and the equilibrium value given by the equation does not exceed 3–4 % in the full range of altitudes independent of season or latitude. We have developed the technique of statistic Bayesian evaluation of simultaneous measurements of OH, HO2 and O3 based on the equilibrium equation taking into account the measurement error. The first results of application of the technique to MLS/Aura data are presented in this Technical Note. It has been found that the satellite data of HO2 distribution regularly demonstrates essentially lower altitudes of mesospheric maximum of this component. This has also been confirmed by offline retrieval of HO2 from the MLS primary data.
