Improvements to stratospheric chemistry scheme in the UM-UKCA (v10.7) model: solar cycle and heterogeneous reactions

Dennison, Fraser; Keeble, James; Morgenstern, Olaf; Zeng, Guang; Abraham, N Luke; Yang, Xin ORCID: https://orcid.org/0000-0002-3838-9758. 2019 Improvements to stratospheric chemistry scheme in the UM-UKCA (v10.7) model: solar cycle and heterogeneous reactions. Geoscientific Model Development, 12 (3). 1227-1239. 10.5194/gmd-12-1227-2019

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Official URL: https://www.geosci-model-dev.net/12/1227/2019/

Abstract/Summary

Improvements are made to two areas of the United Kingdom Chemistry and Aerosol (UKCA) module, which forms part of the Met Office Unified Model (UM) used for weather and climate applications. Firstly, a solar cycle is added to the photolysis scheme. The effect on total column ozone of this addition was found to be around 1–2% in mid-latitude and equatorial regions in phase with the solar cycle. Secondly, reactions occurring on the surfaces of polar stratospheric clouds and sulfate aerosol are updated and extended by modification of the uptake coefficients of five existing reactions and the addition of a further eight reactions involving bromine species. These modifications are shown to reduce the overabundance of modeled total-column ozone in the Arctic during October to February, southern mid-latitudes during August, and the Antarctic during September. Antarctic springtime ozone depletion is shown to be enhanced by 25 DU on average, which now causes the ozone hole to be somewhat too deep compared to observations. We show that this is in part due to a cold bias of the Antarctic polar vortex in the model.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.5194/gmd-12-1227-2019
ISSN:	1991959X
Date made live:	21 Nov 2018 13:18 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/521660

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.5194/gmd-12-1227-2019

ISSN:

1991959X

Date made live:

21 Nov 2018 13:18 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/521660