Preprints
https://doi.org/10.5194/gmd-2022-215
https://doi.org/10.5194/gmd-2022-215
Submitted as: model description paper
15 Dec 2022
Submitted as: model description paper | 15 Dec 2022
Status: this preprint is currently under review for the journal GMD.

Description and evaluation of the new UM-UKCA (vn11.0) Double Extended Stratospheric-Tropospheric (DEST vn1.0) scheme for comprehensive modelling of halogen chemistry in the stratosphere

Ewa M. Bednarz1,a, Ryan Hossaini1,2, Luke Abraham3,4, and Martyn P. Chipperfield5,6 Ewa M. Bednarz et al.
  • 1Lancaster Environment Centre, Lancaster University, Lancaster, UK
  • 2Centre of Excellence in Environmental Data Science, Lancaster University, Lancaster UK
  • 3Department of Chemistry, University of Cambridge, Cambridge, UK
  • 4National Centre for Atmospheric Science (NCAS), UK
  • 5School of Earth and Environment, University of Leeds, Leeds, UK
  • 6National Centre for Earth Observation (NCEO), University of Leeds, Leeds, UK
  • anow at: CIRES, University of Colorado Boulder, and NOAA Chemical Sciences Laboratory, Boulder, CO, USA

Abstract. The paper describes the development and performance of the Double Extended Stratospheric-Tropospheric (DEST vn1.0) chemistry scheme, which forms a part of the Met Office’s Unified Model coupled to the United Kingdom Chemistry and Aerosol (UM-UKCA) chemistry-climate model, the atmospheric composition model of the United Kingdom Earth System Model (UKESM). The scheme extends the standard Stratospheric-Tropospheric Chemistry scheme (StratTrop) by including a range of important updates to the halogen chemistry. These allow process-oriented studies of stratospheric ozone depletion and recovery, including the impacts from both controlled long-lived ozone-depleting substances (ODSs) and emerging issues around uncontrolled very short-lived substances (VSLS). The main updates in DEST are (i) an explicit treatment of 14 of the most important long-lived ODSs; (ii) an inclusion of Br-VSLS emissions and chemistry; and (iii) an inclusion of Cl-VSLS emissions/lower boundary conditions and chemistry. We evaluate the scheme’s performance by comparing DEST simulations against analogous runs made with the standard StratTrop scheme, as well as against observational and reanalysis datasets. Overall, our scheme addresses some significant shortcomings in the representation of atmospheric halogens in the standard StratTrop scheme, and will thus be particularly relevant for studies of ozone layer recovery and processes affecting it, in support of future Ozone Assessment reports.

Ewa M. Bednarz et al.

Status: open (until 11 Feb 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Ewa M. Bednarz et al.

Ewa M. Bednarz et al.

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Short summary
Development and performance of the new DEST chemistry scheme of UM-UKCA is described. The scheme extends the standard StratTrop scheme by including important updates to the halogen chemistry, thus allowing process-oriented studies of stratospheric ozone depletion and recovery, including impacts from both controlled long-lived ozone-depleting substances and emerging issues around uncontrolled very short-lived substances. It will hence aid studies in support of future WMO Ozone Assessment reports.