Preprints
https://doi.org/10.5194/acp-2021-552
https://doi.org/10.5194/acp-2021-552

  05 Jan 2022

05 Jan 2022

Review status: this preprint is currently under review for the journal ACP.

Evaluation of WRF-CHIMERE coupled models for the simulation of PM2.5 in large East African urban conurbations

Andrea Mazzeo1,2, Michael Burrow1, Andrew Quinn1, Eloise A. Marais3, Ajit Singh2, David Ng'ang'a4, Michael J. Gatari4, and Francis D. Pope2 Andrea Mazzeo et al.
  • 1School of Civil Engineering, University of Birmingham, Birmingham UK
  • 2School of Geography Earth and Environmental Sciences – GEES, University of Birmingham, Birmingham UK
  • 3Department of Geography, University College London, London, UK
  • 4Institute of Nuclear Science and Technology, University of Nairobi, Nairobi, Kenya

Abstract. Urban conurbations of East Africa are affected by harmful levels of air pollution. The paucity of local air quality networks and the absence of capacity to forecast air quality make it difficult to quantify the real level of air pollution in this area. The chemistry-transport model CHIMERE has been coupled with the meteorological model WRF and used to simulate hourly concentrations of Particulate Matter PM2.5 for three East African urban conurbations: Addis Ababa in Ethiopia, Nairobi in Kenya and Kampala in Uganda. Two existing emission inventories were combined to test the performance of CHIMERE as an air quality tool for a target monthly period of 2017 and the results compared against observed data from urban and rural sites. The results show that the model is able to reproduce hourly and daily temporal variability of aerosol concentrations close to observations both in urban and rural environments. CHIMERE’s performance as a tool for managing air quality was also assessed. The analysis demonstrated that despite the absence of high-resolution data and up-to-date biogenic and anthropogenic emissions, the model was able to reproduce 66–99 % of the daily PM2.5 exceedances above the WHO 24-hour mean PM2.5 guideline (25 µg m−3) in the three cities. An analysis of the 24-hour mean levels of PM2.5 was also carried out for 17 constituencies in the vicinity of Nairobi. This showed that 47 % of the constituencies in the area exhibited a low air quality index for PM2.5 in the unhealthy category for human health exposing between 10000 to 30000 people/km2 to harmful levels of air contamination.

Andrea Mazzeo et al.

Status: open (until 16 Feb 2022)

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

Andrea Mazzeo et al.

Andrea Mazzeo et al.

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Short summary
The modelling system for meteorology and chemistry-transport processes WRF-CHIMERE has been tested and validated for three conurbations of East Africa using the most up-to-date anthropogenic emissions available. Results show that the model is able to reproduce hourly and daily temporal variability of aerosol concentrations close to observations both in urban and rural environments encouraging the adoption of numerical modelling as a tool for air quality management in East Africa.
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