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Characterization of submicron aerosols and effect on visibility during a severe haze-fog episode in Yangtze River Delta, China
Abstract Particle size, composition and optical properties were measured at a regional atmosphere background station in the Yangtze River Delta (YRD) to understand the formation and evolution of haze-fog episodes in Jan. 2013. The peak of particle number size distribution was in the size range of 80–100 nm during the measurements. PM1 mass concentration contributed 84% to the total particle mass (PM10). Based on visibility and ambient relative humidity, three types of weather conditions (i.e., clear, haze and fog) were classified in this study. The extinction coefficients of PM1 and PM10 under dry conditions were simulated by the Mie model. Under dry conditions, PM1 was found to contribute approximately 91% to the light extinction coefficient of PM10. However, the PM1 with the assumption of dry state was found to contribute approximately 85% to the ambient extinction coefficient of PM10 during clear conditions, 58% during haze conditions and approximately 41% during fog conditions. The variation of the dry PM1 contribution was related to the water uptake of particles under different relative humidity conditions. A severe haze-fog event on Jan. 14–17 was discussed in more detail as a case study. Two episodes were chosen to show that nitrate and organics dominated the aerosol component during the severe haze-fog episode and were related to secondary aerosol formation and air mass origin. Nitrate played a more dominant role than sulfate in heavy haze formation in the YRD region, which was different from the North China Plain region.
Highlights Particle number size distribution characteristic during haze-fog episode. Submicron aerosol influence on light extinction coefficient is evaluated. Secondary aerosol formation controlling haze-fog episode. The effect of air mass origin on haze-fog formation episode.
Characterization of submicron aerosols and effect on visibility during a severe haze-fog episode in Yangtze River Delta, China
Abstract Particle size, composition and optical properties were measured at a regional atmosphere background station in the Yangtze River Delta (YRD) to understand the formation and evolution of haze-fog episodes in Jan. 2013. The peak of particle number size distribution was in the size range of 80–100 nm during the measurements. PM1 mass concentration contributed 84% to the total particle mass (PM10). Based on visibility and ambient relative humidity, three types of weather conditions (i.e., clear, haze and fog) were classified in this study. The extinction coefficients of PM1 and PM10 under dry conditions were simulated by the Mie model. Under dry conditions, PM1 was found to contribute approximately 91% to the light extinction coefficient of PM10. However, the PM1 with the assumption of dry state was found to contribute approximately 85% to the ambient extinction coefficient of PM10 during clear conditions, 58% during haze conditions and approximately 41% during fog conditions. The variation of the dry PM1 contribution was related to the water uptake of particles under different relative humidity conditions. A severe haze-fog event on Jan. 14–17 was discussed in more detail as a case study. Two episodes were chosen to show that nitrate and organics dominated the aerosol component during the severe haze-fog episode and were related to secondary aerosol formation and air mass origin. Nitrate played a more dominant role than sulfate in heavy haze formation in the YRD region, which was different from the North China Plain region.
Highlights Particle number size distribution characteristic during haze-fog episode. Submicron aerosol influence on light extinction coefficient is evaluated. Secondary aerosol formation controlling haze-fog episode. The effect of air mass origin on haze-fog formation episode.
Characterization of submicron aerosols and effect on visibility during a severe haze-fog episode in Yangtze River Delta, China
Shen, X.J. (author) / Sun, J.Y. (author) / Zhang, X.Y. (author) / Zhang, Y.M. (author) / Zhang, L. (author) / Che, H.C. (author) / Ma, Q.L. (author) / Yu, X.M. (author) / Yue, Y. (author) / Zhang, Y.W. (author)
Atmospheric Environment ; 120 ; 307-316
2015-09-02
10 pages
Article (Journal)
Electronic Resource
English