Observational Study Of Size-resolved Aerosol Activation And Hygroscopic Properties In South China

The special properties of an aerosol’s hygroscopic growth and activation can have significant effects on particle number sizes distribution, cloud nucleation, climate forcing, human health and haze formation. This work utilized the data observed at Guangzhou2011.12, Nanjing2012.05, Mt. Huang2012.09-10, to analysis the aerosol activation properties at Guangzhou and Mt. Huang, and make a brief analysis of aerosol hygroscopic characteristics of three areas. A CCN closure has been made based on the size-resolved activation data and environmental aerosol distribution of Guangzhou. A sensitive study of CCN closure has been made to test the three factors used in the calculation of CCN concentration:NCN (Number concentration of Cloud Nuclear), NSD (Normalized Size Distribution), ARSR(Size-resolved Activation Ratio). A single parameter of aerosol hygroscopicity which is named κ has been calculated from GF-PDF data. κ-PDF and the critical point KSC are used to calculate a aerosol activation ratio which also can be used in the CCN Conc. calculation. Here is a brief instruction of the results as follow.(1) The mid-point activation diameters calculated at different SS (0.1%,0.2%,0.4%,0.7%) for Guangzhou and Mt. Huang each are:143.7nm,99.5nm,74.7nm,62.6nm;139.82nm,90.9nm,57.4nm,46.6nm. And the variation of activation ratios shows the activation ability of aerosol particles is mainly determined by its size, but the composition and mixing state have a significant influence (the standard deviation of AR) near the critical position at different supersaturations;(2) The CCN closure study shows:the CCN Conc. calculated by real time NCN, NSD, ARSR correlate well (R2=0.9477) with the observed CCN Conc.,the slope and intercept each is1.156and-39.63. Accurate in loop closing;(3) The sensitive study shows:the influence of the three factors used in CCN Conc. calculation is, NCN> NSD> ARSR. It indicates that mean ARSR, NSD can be used to calculate CCN Conc. in a short time(2or3weeks), the results fix observed data well;(4) ARκ has been calculated from κ-PDF and KSC. A linear fit between computed and measured results was made, the slope and intercept each is1.131and-0.098, correlation coefficient is0.9227. To compare with the observed AR, they fix well at most situation, but have a significant deviation at the critical position at each set SS;(5) The CCN Conc. calculate by ARκhas a good correlation with the observed data, the slope and intercept each is1.265and-455.4, correlation coefficient is0.9412;...