GLOMAP-mode in UKCA linked to Stratospheric Chemistry (StratChem)

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This configuration involves an extension to the UKCA Stratospheric Chemistry (StratChem) scheme to additionally include stratospheric aerosol-precursor chemistry.

In addition to the 36 advected tracers in StratChem, 8 extra gas phase tracers are added for the aerosol chemistry (DMS, SO2, SO3, H2SO4, MSA, CS2, COS, H2S). The sulphur chemistry scheme is essentially that from Weisenstein et al (1997) including updates from WMO (2006).

In this configuration, H2SO4 in the aerosol phase has a non-zero vapour pressure in the stratosphere, calculated following Ayers et al (1980). The GLOMAP-mode aerosol routines have been modified to calculate this vapour pressure and allow evaporation or condensation of sulphuric acid depending on the atmospheric conditions, with the Kelvin effect included according to the mean radius calculated by GLOMAP-mode. The nucleation mechanism of Vehkamakki et al (2002) which is applicable to both tropospheric and stratospheric conditions has also been added.

As for the StratChem chemistry, this extended scheme (StratChem+Aero) uses the sparse-matrix Newton-Raphson solver.

Ayers, G. P., Gillett, R. W. and Gras, J. L. et al (1980) On the vapor pressure of sulfuric acid, Geophys. Res. Lett., vol. 7, no. 6, pp. 433-436, 1980.

WMO (2006): SPARC Assessment of Stratospheric Aerosol Properties, Ed. L. Thomason and T. Peter.

Vehkamakki, H., Kulmala, M., Napari, I. et al (2002): An improved parameterization for sulfuric acid - water nucleation rates for tropospheric and stratospheric conditions, J. Geophys. Res., vol 107, D22, doi:10.1029/2002JD002184, 2002.

Weisenstein, D. K., Yue, G. K., Ko, M. K. W. et al.: A two-dimension model of sulfur species and aerosol, J. Geophys. Res., vol. 102, D11, pp. 13,019-13,035.