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

摘要: Abstract. Improvements are made to two areas of the United Kingdom Chemistry and Aerosol (UKCA) module, which forms part 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 this addition was found be around 1 %–2 % in midlatitude equatorial regions, in phase with cycle. Secondly, reactions occurring surfaces of polar stratospheric clouds sulfate aerosol updated extended by modification uptake coefficients five existing the addition further eight involving bromine species. These modifications shown reduce overabundance modelled column ozone Arctic during October February, southern midlatitudes during August Antarctic September. springtime ozone depletion enhanced by 25 DU average, now causes the ozone hole somewhat too deep compared observations. We show that this due cold bias polar vortex the model.