Results from a new linear O3 scheme with embedded heterogeneous chemistry compared with the parent full-chemistry 3-D CTM 1Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK
2Centre Européen de Recherche et Formation Avancée en Calcul Scientifique, Toulouse, France
3Météo-France, Toulouse, France
Received: 23 Apr 2010 – Published in Atmos. Chem. Phys. Discuss.: 20 May 2010Abstract. A detailed full-chemistry 3-D chemistry and transport model (CTM) is used to evaluate
the current stratospheric O3 parameterisation in the European Centre for
Medium-Range Weather Forecasts (ECMWF) model and to obtain an alternative
version of the ozone scheme implicitly including heterogeneous chemistry.
The approach avoids the inaccurate treatment currently given to
heterogeneous ozone chemistry in the ECMWF model, as well as the
uncertainties of a cold-tracer.
The new O3 scheme (COPCAT) is evaluated within the same CTM used to calculate it.
It is the first time such a comparison has been possible, providing direct information
on the validity of the linear parameterisation approach for stratospheric ozone.
Simulated total column and O3 profiles are compared against Total Ozone Mapping
Spectrometer (TOMS) and Halogen Occultation Experiment (HALOE) observations.
COPCAT successfully simulates polar loss and reproduces a
realistic Antarctic O3 hole.
The new scheme is comparable to the full-chemistry in many regions for multiannual runs.
The parameterisation produces less ozone over the tropics around 10 hPa, compared to
full-chemistry and observations. However, this problem
can be ameliorated by choosing a different ozone climatology for the scheme.
The new scheme is compared to the current ECMWF scheme in the same CTM runs.
The Antarctic O3 hole with the current ECMWF scheme is weaker and disappears earlier
than with the new COPCAT scheme.
Differences between the current ECMWF scheme and COPCAT are difficult to explain
due to the different approach used for heterogeneous chemistry
and differences in the photochemical models used to
calculate the scheme coefficients. Results with the new COPCAT scheme
presented here show that heterogeneous and
homogeneous ozone chemistry can be included in a consistent way in a linear
ozone parameterisation, without any additional tunable parameters, providing a
parameterisation scheme in better agreement with the current knowledge of
stratospheric O3 chemistry than previous approaches.
Revised: 21 Jan 2011 – Accepted: 26 Jan 2011 – Published: 14 Feb 2011
Citation: Monge-Sanz, B. M., Chipperfield, M. P., Cariolle, D., and Feng, W.: Results from a new linear O3 scheme with embedded heterogeneous chemistry compared with the parent full-chemistry 3-D CTM, Atmos. Chem. Phys., 11, 1227-1242, doi:10.5194/acp-11-1227-2011, 2011.