Direct radiative forcing of urban aerosols over Pretoria(25.75°S, 28.28°E) using AERONET Sunphotometer data:First scientific results and environmental impact

作     者：Ayodele Joseph Adesina Kanike Raghavendra Kumar Venkataraman Sivakumar Derek Griffith 

作者机构：Discipline of Physics School of Chemistry and Physics College of Agriculture Engineering and Science Westville CampusUniversity of Kwa Zulu–Natal Durban 4000 South Africa Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration School of Atmospheric PhysicsNanjing University of Information Science and Technology Optronic Sensor Systems Council for Scientific and Industrial Research (CSIR)–DPSS Pretoria 0001 South Africa 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2014年第26卷第12期

页      面：2459-2474页

核心收录：

学科分类：0830[工学-环境科学与工程（可授工学、理学、农学学位）] 07[理学] 070602[理学-大气物理学与大气环境] 0706[理学-大气科学] 

基　　金：supported through Africa Laser Centre (Pretoria) collaborative project funded NRF bi-lateral project(Grand UID:78682) 

主　　题：Pretoria AERONET Aerosol optical depth Single scattering albedo Radiative forcing 

摘      要：The present study uses the data collected from Cimel Sunphotometer of Aerosol Robotic Network（AERONET） for the period from January to December, 2012 over an urban site,Pretoria（PTR; 25.75°S, 28.28°E, 1449 m above sea level）, South Africa. We found that monthly mean aerosol optical depth（AOD, τa） exhibits two maxima that occurred in summer（February） and winter（August） having values of 0.36 ± 0.19 and 0.25 ± 0.14,respectively, high-to-moderate values in spring and thereafter, decreases from autumn with a minima in early winter（June） 0.12 ± 0.07. The Angstrom exponents（α440–870） likewise,have its peak in summer（January） 1.70 ± 0.21 and lowest in early winter（June） 1.38 ± 0.26,while the columnar water vapor（CWV） followed AOD pattern with high values（summer） at the beginning of the year（February, 2.10 ± 0.37 cm） and low values（winter） in the middle of the year（July, 0.66 ± 0.21 cm）. The volume size distribution（VSD） in the fine-mode is higher in the summer and spring seasons, whereas in the coarse mode the VSD is higher in the winter and lower in the summer due to the hygroscopic growth of aerosol *** single scattering albedo（SSA） ranged from 0.85 to 0.96 at 440 nm over PTR for the entire study period. The averaged aerosol radiative forcing（ARF） computed using SBDART model at the top of the atmosphere（TOA） was- 8.78 ± 3.1 W/m2, while at the surface it was- 25.69 ± 8.1 W/m2 leading to an atmospheric forcing of ＋ 16.91 ± 6.8 W/m2, indicating significant heating of the atmosphere with a mean of 0.47 K/day.