Advection
; Aerosols
; Atmospheric thermodynamics
; Clouds
; Cooling
; Heating
; Land use
; Troposphere
; Anthropogenic aerosols
; Anthropogenic effects
; Atmosphere-land interactions
; Community atmosphere model
; East Asian summer monsoon
; Monsoons
; Tropospheric temperature
; Urban meteorology
; Atmospheric movements
; aerosol
; air temperature
; anthropogenic effect
; atmosphere-biosphere interaction
; atmospheric circulation
; atmospheric transport
; land cover
; land use change
; latent heat flux
; monsoon
; regional climate
; summer
; troposphere
; urban climate
; urbanization
; warming
; China
英文摘要:
Impacts of urbanization and anthropogenic aerosols in China on the East Asian summer monsoon (EASM) are investigated using version 5.1 of the Community Atmosphere Model (CAM5.1) by comparing simulations with and without incorporating urban land cover and/or anthropogenic aerosol emissions. Results show that the increase of urban land cover causes large surface warming and an urban frictional drag, both leading to a northeasterly wind anomaly in the lower troposphere over eastern China (EC). This weakens the southerly winds associated with the EASM and causes a convergence anomaly in southern China (SC) with increased ascent, latent heating, and cloudiness. The enhanced latent heating reinforces surface convergence and upper-level divergence over SC, leading to more northward advection in the upper level into northern China (NC) and descending between 30° and 50°N over East Asia. Cloudiness reduction, adiabatic heating, and warm advection over NC all enhance the urban heating there, together causing anomalous tropospheric warming at those latitudes over East Asia. Anthropogenic aerosols cause widespread cooling at the surface and in the troposphere over EC, which decreases the summer land-ocean thermal contrast, leading to a weakened EASM circulation with reduced moisture transport to NC. This results in wetter and drier conditions over SC and NC, respectively. When both the urbanization and anthropogenic aerosols are included in the model, aerosols' cooling is partially offset by the urban heating, and their joint effect on the circulation is dominated by the aerosols' effect with a reduced magnitude. In the combined experiment, surface and tropospheric temperatures are also altered by the decrease (increase) in cloudiness over NC (SC) with most of the cooling confined to SC, which further weakens the EASM circulation.
Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China; Joint International Research Laboratory of Climate and Environment Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, Jiangsu, China; Department of Geography, Northern Illinois University, DeKalb, IL, United States; Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, NY, United States; National Center for Atmospheric Research, Boulder, CO, United States
Recommended Citation:
Jiang Z.,Huo F.,Ma H.,et al. Impact of Chinese urbanization and aerosol emissions on the East Asian summer monsoon[J]. Journal of Climate,2017-01-01,30(3)