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.

Acknowledgements

We are grateful to Dr Fabrizio Esposito and his colleagues from the Istituto di Metodologie Inorganiche e dei Plasmi, Bari, Italy for providing the code of calculation of reaction (11)11 rate constant. The study was supported by grant RFBR no. 09-05-00 694-а.