The Study Of Aerosol Hygroscopic Parameterization And The Effect On Cloud Or Fog Microphysics At Mt. Huang

Aerosol chemical composition was an important factor affecting cloud or fog microphysical characteristics, the combined effect of aerosol compositions should be considered in the study of the impact of aerosols on climate. The traditional cloud model, modes were required to set fixed component and a large number of parameters, it makes the calculated error larger and efficiency lower. Therefore we need to use κ comprehensively reflect the influence of multi-component aerosols on cloud microphysical characteristics without having to know the specific chemical composition of aerosols. Due to the current domestic and international research on κ was rare, especially in Mt. Huang, in this study by analyzing the aerosol hygroscopic parameter κ and the aerosol ionic components observed in July,2014 in Mt. Huang, the characterizations of the multi-size aerosol hygroscopic parameter κ, and which parameterization were investigated. Then the aerosol hygroscopic parameter κ distributions and "dry" size spectra were used as input to a κ cloud parcel model to investigate the influence of multi-component aerosols on cloud or fog microphysics. The κ, ionic components and "dry" size spectra were sampled with Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA), Anderson cascade impactor and wide-range particle spectrometer (WPS).The sampling site was mainly affected by the southwest, northern and the southeast air mass during the summer. The values of κ first increased and then decreased, and changed from 0.2 to 0.48. When the particle size less than 1.1μm, the highest value appeared in the air masses from southwest, and the lowest values appeared in the air masses from southeast, but just the opposite when the particle size greater than 1.1 μm. The parametric equation for the aerosol particle size less than 1.1 μm and greater than 1.1 μm were κreg=0.12+0.45fNH++0.63fSO42-+0.18fWSOC and κreg=0.01+0.78fNH4++0.76fNO3-+0.8fSO42--0.28fCa2++0.14fWSOC. The equations can predict the values of multi-size κ well, and the predictive deviation values were in the range of 30%. The forecast values of κreg were highly correlation with calculated values of κ, and passed the test of significance of 99% confidence level.The super saturation of aerosol particles is decreases with the increasing of dry radius. When the radius was less than 0.01 μm, the critical super saturation decreases very rapidly with radius increasing. The critical super saturation quite different with different air masses, the maximum appeared in the air mass from southeast, and the minimum appeared in the air mass from southwest. The number of cloud or fog droplets increases with the rising of updraft velocity. When the updraft velocity was the same, cloud or fog droplet number concentrations were different in different backgrounds, the cloud or fog droplet number concentrations were highest when southwest air mass controlling, but the lowest values appeared in the southeast air mass. Cloud or fog droplet number spectrums were different in different air masses and different updraft velocity. Under the same backgrounds, the cloud or fog droplet number spectrum became wider when updraft velocity was small. When the updraft velocity was the same, cloud or fog droplet number spectrums were widest influenced by the southwest air mass, and narrowest spectrums appeared in the southeast air mass.During the observation, the cloud or fog droplet number concentrations showed a decreasing trend with the particle size increasing. In different air masses backgrounds, the cloud drop number concentrations were largest in the southwest air masses, and the least values were in the southeast air masses. Compared with the observed number spectrum, the simulation number of cloud or fog droplets was higher when the particle radius was within the range of the 3-4μm, and this difference becomes larger with increasing of updraft velocity. The difference between the observed maximum number of cloud or fog droplet and simulation values was smaller. The improved κ cloud model can better simulate the effect of multi-component aerosols on cloud or fog microphysical characteristics than traditional cloud model.