Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
doi:10.5194/gmd-2017-19
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Model description paper
07 Mar 2017
Review status
This discussion paper is under review for the journal Geoscientific Model Development (GMD).
Update of the SWIFT model for polar stratospheric ozone loss (SWIFT version 2)
Ingo Wohltmann, Ralph Lehmann, and Markus Rex Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
Abstract. The SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in Global Climate Models (GCMs) and Earth System Models (ESMs) to enable the simulation of interactions between the ozone layer and climate. So far, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. SWIFT is based on a set of coupled differential equations, which simulate the polar vortex averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at single processes and an independent validation of the different parameterizations for the single processes contained in the differential equations. The training of the original SWIFT model was based on fitting complete model runs to satellite observations and did not allow this. A revised formulation of the system of differential equations is developed, which closely fits vortex averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the SWIFT model are purely chemical rates of change in the new version, while the rates of change in the original SWIFT version included a transport effect caused by the original training on satellite data. Hence, the new version allows for an implementation into climate models in combination with an existing stratospheric transport scheme. Finally, the model is now formulated on several vertical levels encompassing the vertical range in which polar ozone depletion is observed. The results of the SWIFT model are validated with independent MLS satellite observations and the results of the original detailed chemistry model of ATLAS.

Citation: Wohltmann, I., Lehmann, R., and Rex, M.: Update of the SWIFT model for polar stratospheric ozone loss (SWIFT version 2), Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-19, in review, 2017.
Ingo Wohltmann et al.
Ingo Wohltmann et al.
Ingo Wohltmann et al.

Viewed

Total article views: 215 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
174 29 12 215 3 13

Views and downloads (calculated since 07 Mar 2017)

Cumulative views and downloads (calculated since 07 Mar 2017)

Viewed (geographical distribution)

Total article views: 215 (including HTML, PDF, and XML)

Thereof 215 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 27 Apr 2017
Publications Copernicus
Download
Share