随着城市化和工业化进程的加快,南京城市热岛效应显著,细颗粒物污染加剧,对大气环境、气候变化和人体健康产生重要影响。本文基于观测资料,分析了南京市不同颗粒物浓度水平下城市热岛强度的变化特征;利用光学特性模型OPAC(optical properties of aerosols and clouds model)和辐射传输模型TUV(troposphere ultraviolet-visible model)估计了气溶胶的光学厚度及辐射强迫;定量分析了细颗粒物对城市热岛强度的影响及其可能机制。结果表明:南京城市热岛强度范围为-0.5~1.3K,冬季强于夏季。细颗粒物质量浓度范围为32~135mug/m~3,冬季高于夏季,城区和郊区差别不大;当大气中细颗粒物质量浓度较高时,城市热岛强度相对较弱;南京城郊气溶胶光学厚度变化范围为0.28~1.01,在地面产生的辐射强迫达-3.88~-4.72 W·m~(-2);由于城区和郊区下垫面、人为热、细颗粒物浓度水平的差异,造成城郊近地面降温的不同,导致细颗粒物对城市热岛强度的削弱,夏季减弱0.1K,冬季减弱0.2K。
英文摘要:
With the rapid development of the urbanization and industrialization,heat island effect in Nanjing has been more striking.The air pollution of particulate matters has a bad impact on the atmospheric environment,climate change and citizens.This paper analyses variation characteristics of heat island intensity under different particulate matters concentration levels with the observations in Nanjing.The OPAC(optical properties of aerosols and clouds)and TUV(troposphere ultraviolet-visible)models are used to calculate optical thickness and radiation forcing of aerosols as well as study the physical mechanism of the aerosols affecting the heat island intensity.The heat island intensity of Nanjing,which is stronger in winter than in summer,changes between-0.5K and 1.3K.The fine particle mass concentration ranges from 32to 135mug/m~3,which is higher in winter than in summer.The aerosols have an extinction effect on the heat island.The higher aerosols mass concentration,the lower heat island intensity.There is an apparent difference in different seasons.The optical thickness of aerosols in the suburb in Nanjing changes between 0.28 and1.01 and the radiation forcing ranges from -3.88 W·m~(-2) to-4.72 W·m~(-2).Due to the differences of underlying surface,anthropogenic heat and particulate matter concentration, the surface temperature declines differently in urban and rural area.In general,the particulate matter weakens the urban heat island as 0.1 K in summer and 0.2 K in winter.