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Air Pollution

Transboundary Pollutant Dispersion (Regional/Urban Scale)

Multi-scale numerical simulation on transboundary air pollutant dispersion

In Singapore, citizens are exposed to PM pollution seasonally caused by large-scale burning from Indonesia, including Sumatra and Kalimantan. Air pollution, such as gaseous pollutants and particulate matter (PM) pollutants, has been linked to cardiopulmonary morbidity and mortality as well as to lung cancer (Kunzli, Kaiser et al. 2000, World Health Organization (WHO) 2008).

Given its nature of ubiquitous and involuntary exposure, air pollution in cities is considered a significant public health concern. To address the above-mentioned air quality issue, this study aims to improve urban permeability to promote air pollutant dispersion.

Multi-scale numerical simulations, i.e., Weather Research and Forecasting (WRF) and Computational Fluid Dynamics (CFD), were applied. We conducted WRF modelling to investigate the regional dispersion, and downscale the modelling results to the urban scale using CFD simulation. On one hand,  WRF can describe the transport of transboundary pollution from emission sources to other cities or countries, but cannot model the impact of urban surface roughness elements (i.e. buildings) on air pollutant dispersion. On the other hand,  CFD can include detailed building typologies and urban morphologies in simulations.

Outputs:

  • WRF modelling results indicate that the surrounding terrain, i.e. high mountains and seasonal monsoon, are the main two reasons why concentrations at Singapore and emission locations could even be similar.
  • CFD simulation indicates that the way of urban planning or urban morphology has little impact on pollutant dispersion, since transboundary pollutant is at larger scale and well mixed by turbulence.

Conference presentation:

  • Li XX, Yuan C, 2021, Multiscale Modelling of Transboundary Transport of Air Pollution in 2015 Southeast Asia Biomass Burning, Proceeding in Asia Oceania Geoscience Society (AOGS), Singapore. (Invited)

Figure. WRF modelling results.