Model analysis of aerosol optical depth distributions over East Asia

Based on simulated major aerosol concentrations (e.g., sulfate, nitrate, ammonium, organic carbon, black carbon, and sea salt) over East Asia during the year 2005 by using the Multi-scale Air Quality modeling system (RAMS-CMAQ), the aerosol optical depth (AOD) was calculated by the reconstruction mass-extinction method and then analyzed to explore its characteristics in temporal-spatial distributions. For evaluating the model performances, simulated AOD values were compared against observations at stations of the Aerosol Robotic Network (AERONET) and the Chinese Sun Hazemeter Network (CSHNET). The comparison shows that the model can well reproduce observed temporal and spatial features of AOD, especially in natural environment. However, the simulated AOD values are underestimated over urban and suburban regions with dense human activities. Analysis of simulation results indicates that AOD varies significantly in time and space, and generally, AOD values are lower in summer and higher in winter. Excluding the contribution from soil dust aerosols, high AOD values (over 0.8) are found over the Sichuan Basin, South China, and Central China in several months, while low values (less than 0.2) are over northern and western areas of East Asia and southern sea regions. Analysis also shows that aerosols such as sulfate, nitrate, and ammonium are main contributors to AOD in East Asia, and their contributions are over 80% in most high AOD areas, while black carbon aerosols play an important role in northern China where dense human activities exist, especially in the winter time.

[1]  D. Koch,et al.  Trends in tropospheric aerosol loads and corresponding impact on direct radiative forcing between 1950 and 1990: A model study , 2000 .

[2]  Thomas E. Graedel,et al.  Global gridded inventories of anthropogenic emissions of sulfur and nitrogen , 1996 .

[3]  Steven J. Ghan,et al.  Aerosol Properties and Processes: A Path from Field and Laboratory Measurements to Global Climate Models , 2007 .

[4]  Zhang Mei.  A Multi-Scale Air Quality Modeling System and Its Evaluation I. Introduction to the Model System and Simulation of Meteorological Parameters , 2005 .

[5]  J. Nicolás,et al.  Factors affecting levels of aerosol sulfate and nitrate on the Western Mediterranean coast , 2008 .

[6]  I. Vardavas,et al.  Global distribution of aerosol direct radiative forcing in the ultraviolet and visible arising under clear skies , 2004 .

[7]  Haizhen Yang,et al.  Concentration and chemical composition of PM2.5 in Shanghai for a 1-year period , 2003 .

[8]  M. Jacobson.  Global direct radiative forcing due to multicomponent anthropogenic and natural aerosols , 2001 .

[9]  Yang Sun,et al.  Aerosol optical depth (AOD) and Angstrom exponent of aerosols observed by the Chinese Sun Hazemeter Network from August 2004 to September 2005 , 2007 .

[10]  Byron W. Blomquist,et al.  Transport and transformation of sulfur compounds over East Asia during the TRACE-P and ACE-Asia campaigns , 2004 .

[11]  Kebin He,et al.  The characteristics of PM2.5 in Beijing, China , 2001 .

[12]  B. Holben,et al.  Single-Scattering Albedo and Radiative Forcing of Various Aerosol Species with a Global Three-Dimensional Model , 2002 .

[13]  A. Bouwman,et al.  Emission database for global atmospheric research (Edgar) , 1994, Environmental monitoring and assessment.

[14]  H. Ueda,et al.  MICS-Asia II: The model intercomparison study for Asia Phase II methodology and overview of findings , 2008 .

[15]  P. Russell,et al.  Direct aerosol radiative forcing in the Yangtze delta region of China: Observation and model estimation , 2003 .

[16]  F. Binkowski,et al.  The Regional Particulate Matter Model 1. Model description and preliminary results , 1995 .

[17]  W. Malm,et al.  Spatial and seasonal trends in particle concentration and optical extinction in the United States , 1994 .

[18]  Owen B. Toon,et al.  A global average model of atmospheric aerosols for radiative transfer calculations , 1976 .

[19]  Meigen Zhang.  Large-scale structure of trace gas and aerosol distributions over the western Pacific Ocean during TRACE-P , 2003 .

[20]  D. Koch,et al.  Linking future aerosol radiative forcing to shifts in source activities , 2007 .

[21]  Junji Cao,et al.  Regional modeling of organic aerosols over China in summertime , 2008 .

[22]  G. Carmichael,et al.  Contribution of biomass and biofuel emissions to trace gas distributions in Asia during the TRACE‐P experiment , 2003 .

[23]  James G. Hudson,et al.  Evaluation of aerosol direct radiative forcing in MIRAGE , 2001 .

[24]  M. Jinzhong,et al.  Modeling Sulfate Aerosol and Its Radiative Forcing over China , 2004 .

[25]  J. Roger,et al.  Simulation of aerosol radiative properties with the ORISAM-RAD model during a pollution event (ESCOMPTE 2001) , 2006 .

[26]  Meigen Zhang,et al.  Modeling of organic carbon aerosol distributions over east asia in the springtime , 2004 .

[27]  T. Trautmann,et al.  Aerosol modeling over Europe: 2. Interannual variability of aerosol shortwave direct radiative forcing , 2007 .

[28]  David G. Streets,et al.  Large‐scale structure of trace gas and aerosol distributions over the western Pacific Ocean during the Transport and Chemical Evolution Over the Pacific (TRACE‐P) experiment , 2003 .

[29]  R. Mewaldt,et al.  Charge states of solar energetic particles using the geomagnetic cutoff technique: SAMPEX measurements in the 6 November 1997 solar particle event , 1999 .

[30]  Jonathan P. Taylor,et al.  Aircraft observations and modeling of sky radiance distributions from aerosol during TARFOX , 1999 .

[31]  P. Russell,et al.  Estimation of aerosol direct radiative effects over the mid‐latitude North Atlantic from satellite and in situ measurements , 1999 .

[32]  Rohit Mathur,et al.  A comparison of CMAQ‐based aerosol properties with IMPROVE, MODIS, and AERONET data , 2007 .

[33]  Michael H. Bergin,et al.  Measurement of aerosol chemical, physical and radiative properties in the Yangtze delta region of China , 2002 .

[34]  Wang Xi.  Estimation of the Direct Radiative Forcing Due to Anthropogenic Sulfate over Eastern Asia , 2001 .

[35]  W. Stockwell,et al.  The second generation regional acid deposition model chemical mechanism for regional air quality modeling , 1990 .

[36]  李晓文,et al.  THE COOLING OF SICHUAN PROVINCE IN RECENT 40 YEARS AND ITS PROBABLE MECHANISMS , 1995 .