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Chapter 8. Methane oxidation
IFS documentation Front Page
Chapter 1. Overview
Chapter 2. Radiation
Chapter 3. Turbulent diffusion and interactions with the surface
Chapter 4. Subgrid-scale orographic drag
Chapter 5. Convection
Chapter 6. Clouds and large-scale precipitation
Chapter 7. Land suface parametrization
Chapter 8. Methane oxidation
Chapter 9. Climatological data
REFERENCES
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8.1 Introduction
A study of stratospheric humidity in analyses and multi-year simulations has shown that the ECMWF system prior to 1999 was capable of producing a broadly realistic distribution of water vapour at, and immediately above, the tropopause, and that the slow upward transfer of water vapour in the tropical stratosphere could be captured quite reasonably given sufficiently fine vertical resolution in the model (Simmons et al. 1999). However, values of water vapour in the tropical upper stratosphere, and throughout much of the extratropical stratosphere, were too low. This deficiency has now been remedied by the introduction of a simple parametrization of the upper-stratospheric moisture source due to methane oxidation. A sink representing photolysis in the mesosphere is also included. The scheme was derived as a simplification of an approach adopted by Peter Stott and Anne Pardaens at the Department of Meteorology, University of Edinburgh, notes on which and helpful references were supplied by Bob Harwood.
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05.04.2002 |
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