Model of electronic-vibrational kinetics of the O3 and O2 photolysis products in the middle atmosphere: applications to water vapour retrievals from SABER/TIMED 6.3 μm radiance measurements

Abstract

In this work, we present a methodology of simple yet accurate calculations of H2O(v 2) vibrational levels pumping from the collisions with vibrationally excited O2(X3Σ − g , v = 1) molecules, which is required for correct retrievals of H2O volume mixing ratios from the 6.3 μm band radiance. The electronic-vibrational kinetics model of O2 and O3 photolysis products used in this study includes 44 electronic-vibrational states of the O2 molecule (three states of O2(b1Σ + g , v), six states of O2(a1Δ g , v) and 35 states of O2(X3Σ − g , v)) as well as the first excited state of atomic oxygen, O(1D) and considers more than 100 photochemical reactions linking these states. We introduce the Resulting Quantum Output (RQO) approach that describes the O2(X3Σ − g , v = 1) production quantum yield per one act of O3 photolysis in the Hartley, Huggins, Chappuis and Wulf bands (200–900 nm). We demonstrate that the RQO weakly depends on latitude and season, and suggest a parameterization formula for the altitude dependence of this parameter. We show the application of RQO to H2O retrievals from the 6.3 µm broadband radiance measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER)/Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) instrument that has been performing remote sensing of the Earth's atmosphere in the 13–110 km altitude range from 2002 onwards.