The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MK II in a cloud-free and nonfrontal dust condition on 24 April...The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MK II in a cloud-free and nonfrontal dust condition on 24 April 2006. The total dust column was calculated by using an integration method of the particle size distribution; the mean value was 1.42±0.30 g m 2. A linear correlation between the total dust column and the aerosol optical depth （AOD） with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study; the results were lower than these calculated by the integration method. A reasonable factor of 3.2 g m^-2 was achieved by minimizing the standard deviation （SD） of the two methods. The two layers model, which includes the deposition processes of turbulent transfer, Brownian diffusion, impaction and gravitational settling over the sea＇s surface, was used to calculate the dry deposition flux; the mean value was 5.05±2.49 μg m^-2 s^-1. A correlation among the total dust column, dry deposition flux, AOD, and effective radius was discussed. The correlation between the total better than that between dust column and the AOD was the total dust column and the effective radius; however, the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.展开更多
The fine-mode aerosol absorption optical depth（AAOD）retrieved from the Aerosol Robotic Network（AERONET）has been used in previous studies to calculate the radiative forcing of black carbon（BC）aerosol,assuming tha...The fine-mode aerosol absorption optical depth（AAOD）retrieved from the Aerosol Robotic Network（AERONET）has been used in previous studies to calculate the radiative forcing of black carbon（BC）aerosol,assuming that the absorption by fine-mode aerosols（diameter ≤ 1 μm）is primarily from BC while the absorption by larger particles（diameter 1 μm）is principally from dust.In the present study,the Community Earth System Model was used to simulate and quantify the contribution of fine-mode dust to fine-mode AAOD in eastern China（29–41°N,104–122°E）—an area where concentrations of BC are high.The simulated fine-mode dust concentrations were constrained by observations from nine sites belonging to the Chinese Meteorological Administration Atmosphere Watch Network.Averaged over eastern China,the simulated annual mean fine-mode dust AAOD was 3.6 × 10-3,with the maximum AAOD in spring and the minimum value in winter.The contribution of fine-mode dust to the total fine-mode AAOD（sum of fine-mode dust,BC,and organic carbon）in winter,spring,summer,and autumn was 3.4%,25.2%,12.5%,and 14.9%,respectively,with an annual mean value of 15.1%.The results indicate the importance of removing fine dust AAOD when the AERONET fine-mode AAOD is used for calculating the radiative forcing of BC in eastern China.展开更多
基金funded by the National BasicResearch Program of China (Grant No. 2006CB403702)the Public Meteorology Special Foundation of Ministry of Science and Technology (Grant No. GYHY200706036)the National Natural Science Foundation of China (Grant No. 60638020)
文摘The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MK II in a cloud-free and nonfrontal dust condition on 24 April 2006. The total dust column was calculated by using an integration method of the particle size distribution; the mean value was 1.42±0.30 g m 2. A linear correlation between the total dust column and the aerosol optical depth （AOD） with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study; the results were lower than these calculated by the integration method. A reasonable factor of 3.2 g m^-2 was achieved by minimizing the standard deviation （SD） of the two methods. The two layers model, which includes the deposition processes of turbulent transfer, Brownian diffusion, impaction and gravitational settling over the sea＇s surface, was used to calculate the dry deposition flux; the mean value was 5.05±2.49 μg m^-2 s^-1. A correlation among the total dust column, dry deposition flux, AOD, and effective radius was discussed. The correlation between the total better than that between dust column and the AOD was the total dust column and the effective radius; however, the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.
基金supported by the National Basic Research Program of China(973 Program,[grant number 2014CB441202])the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA05100503]
文摘The fine-mode aerosol absorption optical depth（AAOD）retrieved from the Aerosol Robotic Network（AERONET）has been used in previous studies to calculate the radiative forcing of black carbon（BC）aerosol,assuming that the absorption by fine-mode aerosols（diameter ≤ 1 μm）is primarily from BC while the absorption by larger particles（diameter 1 μm）is principally from dust.In the present study,the Community Earth System Model was used to simulate and quantify the contribution of fine-mode dust to fine-mode AAOD in eastern China（29–41°N,104–122°E）—an area where concentrations of BC are high.The simulated fine-mode dust concentrations were constrained by observations from nine sites belonging to the Chinese Meteorological Administration Atmosphere Watch Network.Averaged over eastern China,the simulated annual mean fine-mode dust AAOD was 3.6 × 10-3,with the maximum AAOD in spring and the minimum value in winter.The contribution of fine-mode dust to the total fine-mode AAOD（sum of fine-mode dust,BC,and organic carbon）in winter,spring,summer,and autumn was 3.4%,25.2%,12.5%,and 14.9%,respectively,with an annual mean value of 15.1%.The results indicate the importance of removing fine dust AAOD when the AERONET fine-mode AAOD is used for calculating the radiative forcing of BC in eastern China.
