24 Mar 2021

24 Mar 2021

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

Dispersion of particulate matter (PM2.5) from wood combustion for residential heating: Optimisation of mitigation actions based on large-eddy simulations

Tobias Wolf, Lasse H. Pettersson, and Igor Esau Tobias Wolf et al.
  • Nansen Environmental and Remote Sensing Center, Thormøhlens gate 47, 5006, Bergen, Norway

Abstract. Many cities in the world experience significant air pollution from residential wood combustion. Such an advection-diffusion problem as applied to geographically distributed small-scale pollution sources presently does not have a satisfactory theoretical or modelling solution. For example, statistical models do not allow for pollution accumulation in local stagnation zones – a type of phenomena that is commonly observed over complex terrain. This study applies a Parallelized Atmospheric Large-eddy simulation Model (PALM) to investigate dynamical phenomena that control variability and pathways of the atmospheric pollution emitted by wood-burning household stoves. The model PALM runs with a real spatial distribution of the pollution source and with realistic surface boundary conditions that characterize a medium-sized urban area fragmented by water bodies and hills. Such complex geography is expected to favor local air quality hazards, which makes this study of general interest. The case study here is based on winter conditions in Bergen, Norway. We investigate the turbulent diffusion of a passive scalar associated with small sized particles (PM2.5) emitted by household stoves. The study considers air pollution effects that could be observed under different policy scenarios of stove replacement; modern wood stoves emit significantly less PM2.5 than the older ones, but replacement of stoves is costly and challenging process. To solve the advection-diffusion problem, we used the PALM model at spatial resolution of 10 m in an urban-sized modelling domain of 15 km by 15 km. We found significant accumulation of near-surface pollution in the local stagnation zones. The observed concentrations were larger than concentrations due to the local PM2.5 emission, thus, indicating dominant trans-boundary contribution of pollutants for other districts. We demonstrate how the source of critical pollution can be attributed through model disaggregation of emissions from specific districts. The study reveals a decisive role of local air circulations over complex terrain that makes high-resolution modelling indispensable for adequate management of the urban air quality.

This modelling study has important policy-related implications. Uneven spatial distribution of the pollutants suggests prioritizing certain limited urban districts in policy scenarios. We show that focused efforts towards stove replacement in specific areas may have dominant positive effect on the air quality in the whole municipality. The case study identifies urban districts where limited incentives would result in the strongest reduction of the population’s exposure to PM2.5.

Tobias Wolf et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-81', Anonymous Referee #2, 13 Apr 2021
    • AC1: 'Reply on RC1', Igor Esau, 10 May 2021
  • RC2: 'Comment on acp-2021-81', Anonymous Referee #1, 31 May 2021

Tobias Wolf et al.

Tobias Wolf et al.


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Short summary
House heating by wood-burning stoves is cozy and needed in boreal cities, e.g., Bergen, Norway. But smoke (aerosols) from stoves may reduce urban air quality. It can be transported over long distance excessively polluting some neighborhoods. Who will suffer the most? Our modelling study looks at urban pollution in unprecedented meter-sized details tracing smoke pathways and turbulent dispersion in a typical city. We prototype effective policy scenarios to mitigate urban air quality problems.