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The OsloCTM3 was introduced by Søvde et al. (2012). The model is based on the University of California, Irvine (UCI) CTM. With a few exceptions, the code is fully Fortran90.

Its predecessor, the OsloCTM2, was a fusion of a tropospheric CTM and a stratospheric CTM. The tropospheric CTM, Oslo CTM-1 (Sundet, 1997; Berntsen and Isaksen, 1997), was based on the NASA/Goddard Institute for Space Studies (GISS) CTM with the incorporation of an extensive photochemical scheme and was later extended with various applications. The chemistry part of the stratospheric Oslo SCTM-1 (Rummukainen, 1996), based on Stordal et al (1985), was later included in the CTM-1 to create the Oslo CTM2, a CTM with comprehensive chemistry schemes for both the troposphere and the stratosphere (Gauss, 2003). In developing the OsloCTM2 with full tropospheric and stratospheric chemistry, a heterogeneous chemistry scheme (Carslaw et al, 1995) was included. However, it yielded too low chlorine activation and was later improved with a new scheme for microphysics and heterogeneous chemistry, to better represent the formation of PSCs, including denitrification and dehydration (see Søvde et al, 2008). Additionally, the calculation of photo-dissociation coefficients was updated to the Fast-J method (Wild et al, 2000; Bian and Prather, 2002), and the vertical resolution was improved. The parametrization of lightning and aircraft emissions, both important for the nitrogen budget in the UTLS, were refined in that process.

 

References

Berntsen, T., and I. S. A. Isaksen: A global 3-D chemical transport model for the troposphere, 1, Model description and CO and Ozone results, J. Geophys. Res., 102(D17), 21239-21280, doi:10.1029/97JD01140, 1997.

Bian, H. S., and M. J. Prather: Fast-J2: Accurate simulation of stratospheric photolysis in global chemical models, J. of Atmos. Chem., 41(3), 281-296, doi:10.1023/A:1014980619462, 2002.

Carslaw, K., B. Luo, and T. Peter: An analytic expression for the composition of aqueous HNO3+H2SO4 stratospheric aerosols including gas phase removal of HNO3, Geophys. Res. Letters, 22(14), 1877-1880, doi:10.1029/95GL01668, 1995.

Gauss, M.: Impact of aircraft emissions and ozone changes in the 21st century: 3-D model studies, PhD thesis, Department of Geosciences, University of Oslo, ISSN 1501-7710, No. 304. Contact address: Section of Meteorology and Oceanography, PB. 1022 Blindern, 0315 Oslo, Norway, 2003.

Rummukainen, M.: Modeling stratospheric chemistry in a global three-dimensional chemical transport model, SCTM-1. Model development, Finnish Meteorological Institute Contributions, vol 19, 1996.

Stordal, F., I. S. A. Isaksen, and K. Horntvedt: A diabatic circulation two-dimensional model with photochemistry: Simulations of ozone and long-lived tracers with surface sources, J. Geophys. Res., 90, 5757-5776, doi:10.1029/JD090iD03p05757, 1985.

Sundet, J. K.: Model Studies with a 3-D Global CTM using ECMWF data, PhD thesis, Department of Geosciences, University of Oslo. Contact address: Section of Meteorology and Oceanography, PB. 1022 Blindern, 0315 Oslo, Norway, 1997.

Søvde, O. A.; M. J. Prather, I. S. A. Isaksen, T. K. Berntsen, F. Stordal, X. Zhu, C. D. Holmes and J. Hsu: The chemical transport model Oslo CTM3, Geosci. Model Dev., 5, 1441-1469, doi:10.5194/gmd-5-1441-2012, 2012.

Søvde, O. A., M, Gauss, S. Smyshlyaev, and I. S. A. Isaksen: Evaluation of the chemical transport model Oslo CTM2 with focus on Arctic winter ozone depletion. J. Geophys. Res., vol. 113, D09304, doi:10.1029/2007JD009240, 2008.