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Turbulence barrier effect during heavy haze pollution events
Yan Ren1, Hongsheng Zhang1, Xiaoye Zhang2
1Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100081, PR China.
The Science of the Total Environment
|November 19, 2020
Summary
Low wind speeds cause intermittent turbulence, hindering pollutant diffusion and leading to heavy haze. A distinct "barrier effect" was identified, explaining pollutant accumulation during these events.
Area of Science:
- Atmospheric Science
- Environmental Science
- Air Quality Research
Background:
- Heavy haze events are linked to low wind speeds and weakened turbulent diffusion in the atmospheric boundary layer (ABL).
- Turbulence can cease at specific altitudes, creating laminar flow and a "barrier layer" that impedes vertical pollutant transport.
- Understanding these phenomena is crucial for explaining pollutant accumulation during severe air pollution episodes.
Purpose of the Study:
- To investigate the physical mechanisms behind pollutant accumulation during heavy haze events.
- To analyze the role of intermittent turbulence and the "barrier effect" in the atmospheric boundary layer (ABL).
- To correlate vertical turbulence characteristics with PM2.5 concentration changes at different heights.
Main Methods:
- Utilized turbulent data from five atmospheric layers.
- Measured PM2.5 (fine particulate matter) concentration at two distinct levels.
- Analyzed the relationship between vertical turbulence variations and PM2.5 distribution.
Main Results:
- A strong correlation was observed between changes in PM2.5 concentration at different heights and the vertical turbulence "barrier effect".
- The "barrier effect" was found to significantly hinder vertical pollutant diffusion.
- Turbulent diffusion conditions directly influence the vertical distribution of PM2.5 concentrations.
Conclusions:
- The study elucidates the physical mechanism driving pollutant accumulation in heavy haze conditions.
- The identified "barrier effect" is a key factor in exacerbating air pollution events.
- Turbulent diffusion dynamics are critical in determining PM2.5 concentration patterns within the ABL.
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