Atmos. Chem. Phys. Discuss., 11, 28969-29002, 2011
www.atmos-chem-phys-discuss.net/11/28969/2011/
doi:10.5194/acpd-11-28969-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
A closure study of cloud condensation nuclei in the North China Plain using droplet kinetic condensational growth model
F. Yang, H. Xue, Z. Deng, C. Zhao, and Q. Zhang
Department of Atmospheric Sciences, School of Physics, Peking University, Beijing, China

Abstract. Aerosol size distribution and cloud condensation nuclei (CCN) number concentration were measured in the North China Plain from 31 December 2009 to 20 January 2010. CCN closure study was performed using these data and droplet kinetic condensational growth model. The calculated CCN concentration with the assumption of pure ammonium sulfate aerosol is 40–140% higher than that observed for the supersaturations in this study. Sensitivity test on aerosol solubility and mixing state indicates that 60–70% mass fraction of ammonium sulfate externally mixed with insoluble material can lead to the calculated CCN concentrations fitting the observations best in the North China Plain during the time period of the field observations, suggesting that a relatively simple scheme may be used for CCN prediction in climate models for this region. Finally, we compare the calculated CCN concentrations from the kinetic condensational growth model and the equilibrium model. The kinetic condensational growth model can simulate droplet growth in a time period under a certain supersaturation, while the equilibrium model only predicts whether a certain aerosol can be activated as CCN under that supersaturation. The CCN concentration calculated with the kinetic model is higher than that with the equilibrium model at supersaturations of 0.056% and 0.083%, because some particles that are not activated from the equilibrium point of view can grow large enough to be considered as CCN in the kinetic model. While at a supersaturation of 0.17%, CCN concentration calculated with the kinetic model is lower than that with the equilibrium model, due to the limitation of droplet kinetic growth. The calculated CCN concentrations using the kinetic model and the equilibrium model are the same at supersaturations of 0.35% and 0.70%.

Citation: Yang, F., Xue, H., Deng, Z., Zhao, C., and Zhang, Q.: A closure study of cloud condensation nuclei in the North China Plain using droplet kinetic condensational growth model, Atmos. Chem. Phys. Discuss., 11, 28969-29002, doi:10.5194/acpd-11-28969-2011, 2011.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share