Publication


F. Kolonjari, et al.
Assessing stratospheric transport in the CMAM30 simulations using ACE-FTS measurements
Atmospheric Chemistry and Physics Discussions, 2017, 2017; doi: 10.5194/acp-2017-352
CMAM30 CFC-11 trichlorofluoromethane CFC-12 dichlorodifluoromethane N2O
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Abstract


Stratospheric transport in global circulation models and chemistry-climate models is an important component in simulating the recovery of the ozone layer as well as changes in the climate system. The Brewer-Dobson circulation is not well constrained by observations and further investigation is required to resolve uncertainties related to the mechanisms driving the circulation. This study has assessed the specified dynamics mode of the Canadian Middle Atmosphere Model (CMAM30) by comparing to the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) profile measurements of CFC-11 (CCl3F), CFC-12 (CCl2F2), and N2O. In the CMAM30 specified dynamics simulation, the meteorological fields are nudged using the ERA-Interim Reanalysis and a specified tracer was used for each species, with hemispherically-defined surface measurements used as the boundary condition. A comprehensive sampling technique along the line-of-sight of the ACE-FTS measurements has been employed to allow for direct comparisons between the simulated and measured tracer concentrations. The model consistently overpredicts tracer concentrations in the lower stratosphere, particularly in the Northern Hemisphere winter and spring seasons. The three mixing barriers investigated, including the polar vortex, the extratropical tropopause, and the tropical pipe, show that there are significant inconsistencies between the measurements and the simulations. In particular, the CMAM30 simulation exhibits too little isentropic mixing in the June-July-August season.

Reference


@article{acp-2017-352,
  author = "F. Kolonjari and D. A. Plummer and K. A. Walker and C. D. Boone and J. W. Elkins and M. I. Hegglin and G. L. Manney and F. L. Moore and D. Pendlebury and E. A. Ray and K. H. Rosenlof and G. P. Stiller",
  title = "Assessing stratospheric transport in the CMAM30 simulations using ACE-FTS measurements",
  year = 2017,
  journal = "Atmospheric Chemistry and Physics Discussions",
  publisher = "Copernicus Publications",
  volume = 2017,
  month = "May",
  keywords = "CMAM30, CFC-11, trichlorofluoromethane, CFC-12, dichlorodifluoromethane, N2O",
  doi = "10.5194/acp-2017-352",
  url = "http://www.atmos-chem-phys-discuss.net/acp-2017-352/"
}
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