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

Geoscientific Model Development (2019)

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.

These modifications reduced the overabundance of modelled total column ozone in the Arctic during October to February, southern midlatitudes during August and the Antarctic during September.

Antarctic springtime ozone depletion was 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.