Modelled long term trends of surface ozone over South Africa

Abstract

Currently little is understood about the potential local response of air quality to anthropogenically induced changes in the regional climate of southern Africa. Such changes are likely to influence the future transport and chemistry of air pollutants over the region. Previous monitoring campaigns have described local trends of surface and profile ozone (e.g. Thompson et al, 2007); however results are spatially limited and temporally sparse. The modelling of surface ozone within a large timescale seeks to provide a spatially comprehensive view of trends while also creating a baseline for comparisons with future projections of air quality through the forcing of air quality models with modelled predicted long term meteorology. Previous research within CSIR Climate Studies, Modelling and Environmental Health (CSM&EH) group has enabled the photochemical air quality model CAMx to be forced with fields from the CCAM atmospheric model, which is also capable of simulating forecasted meteorological conditions at the climate change time scale. The use of forecasted climate change data to drive CAMx is the final objective in a larger research initiative that aims to understand the influence future projected changes in climate will have on air quality. The research presented in this poster discusses the model simulations used to derive the baseline from which comparisons with future simulations will be made. For this baseline trend study, the period 1989-2009 was chosen since necessary ancillary input for CAMx, such as total column ozone and background air quality data, is readily available for this time. Additionally, for CCAM to provide CAMx with realistic meteorological fields, representative real world initial and boundary conditions were required. This came in the form of the NCEP Reanalysis dataset. To date years 1997, 2000, 2003, 2006 and 2009 have been simulated by the CCAMCAMx system, and are presented here as an analysis of trends.