| Autor: |
Yang, Guowei1, Ren, Guoyu1,2 guoyoo@cma.gov.cn, Zhang, Panfeng1,3, Xue, Xiaoying1, Tysa, Suonam Kealdrup1, Jia, Wenqian1, Qin, Yun1, Zheng, Xiang1, Zhang, Siqi1,2 |
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| Zdroj: |
Journal of Geophysical Research. Atmospheres. 9/16/2021, Vol. 126 Issue 17, p1-25. 25p. |
| Abstrakt: |
Whether the urban heat island (UHI) is affected by air pollution in urban areas has attracted much attention. By analyzing the observation data of automatic weather stations and environmental monitoring stations in Beijing from 2016 to 2018, we found a seasonally dependent interlink of the UHI intensity (UHII) and PM2.5 concentration in urban areas. PM2.5 pollution weakens the UHII in summer and winter night, but strengthens it during winter daytime. The correlation between the UHI and PM2.5 concentration has been regulated by the interaction of aerosol with radiation, evaporation and planetary boundary layer (PBL) height. The former two change the surface energy balance via sensible and latent heat fluxes, while the latter affects atmospheric stability and energy exchange. In summer daytime, aerosol‐radiation interaction plays an important role, and the energy balance in urban areas is more sensitive to PM2.5 concentration than in rural areas, thereby weakening UHII. In winter daytime, aerosol‐PBL interaction is dominant, because aerosols lower the PBL height and stabilize atmosphere, weaken the heat exchange with the surrounding, with more heat accumulated in the urban areas and the increased UHII. Changes in evaporation and radiation strengthen the relationship. At night, the change of UHII more depends on the energy stored in the urban canopy. Aerosols effectively reduce the incident energy during daytime, and the long‐wave radiation from the buildings of urban canopy at night becomes less, leading to a weakened UHII. Our analysis results can improve the understanding of climate‐aerosols interaction in megacities like Beijing. Plain Language Summary: A detailed understanding of the relationship between PM2.5 and the urban heat island (UHI) effect is significant for climate change adaption, planning, and sustainable development in urban regions. While Beijing is among the cities with the highest population densities and fastest urbanization rates in China and even the world, the impacts of PM2.5 pollution on UHI remain unclear, and the works using different methods (observations or models), observational data (stations or satellites) and the selecting procedures to classify stations deliver different results. This study demonstrates that the UHI intensities in summer and winter, respectively, exhibit weakening and strengthening tendency as PM2.5 concentration increases. These effects are modulated by aerosol‐radiation interaction in summer and winter, and aerosol interaction with planetary boundary layer and evaporation in winter. Our analysis improves the understanding of interaction of urban climate and air pollution. Key Points: With increasing PM2.5, summer urban heat island intensity (UHII) weakens and winter UHII strengthensWinter PM2.5 pollution weakens the UHII at night but strengthens it during daytimePM2.5 affects UHII via aerosol‐radiation interaction in summer and via aerosol‐planetary boundary layer interaction in winter [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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