Stratospheric hydrogen peroxide: the relationship of theory and observation.

Current theory of stratospheric photochemistry indicates that the photochemical lifetime of hydrogen peroxide (H₂O₂) is short enough in the middle stratosphere (1 day) that the H₂O₂ abundance can be considered to be photochemically controlled. However, H₂O₂ should still be expected to show significant temporal and spatial variability through its sensitivity to transport-related fluctuations in O₃, NO_y(=NO + NO₂ + HNO₃ + HNO₄), and H₂O. From the available observational data on short-term variability in these longer-lived species, H₂O₂ concentrations should vary temporally 4 or 5-fold at altitudes between 15 and 35km. This concentration range about the model profile includes 2 recently reported upper limits for mid-stratospheric H₂O₂. The earlier tentative identification of stratospheric H₂O₂ by Waters et al. (1981) is somewhat larger than the expected upper limit of variation based on a 1D transport-kinetics model. Several implications for stratospheric observation of H₂O₂ arise from its expected variability. Model-predicted H₂O₂ abundances are very sensitive to important kinetic parameters, but small sets of H₂O₂ measurements alone will not be useful to test model behavior. In concert with simultaneous measurements of O₃, H₂O, and HO_y, H₂O₂ abundances could be used to closely verify model treatment of HO_x(=HO + HO₂) photochemistry.-from Authors