Theoretical and observational study on below-cloud rain scavenging of aerosol particles

doi:10.7523/j.issn.2095-6134.2014.03.003

Abstract

Abstract:

As the collision theory for raindrop and aerosol particle is important in below-cloud scavenging, collision efficiency as a function of raindrop diameter (D_p) and aerosol diameter (d_p) is discussed. The scavenging coefficient (SC) under thundercloud is 5 to 6 times higher than those under non-thundercloud when d_p is less than 1 μm. Field measurements of aerosol number concentration at bottom and top of Huangshan mountain from June to August of 2011 were used to analyze the variation characteristics of observed and theoretical SCs. The results show that observed SC variation for ultrafine-sized particle is in reasonable agreement with the theoretical one, and the observed SC is 5 to 6 times higher than the theoretical SC. Submicron-sized particle SC is higher under thundercloud than that under non thundercloud. Based on the observations, exponential relationship between the hour-averaged SC and rainfall intensity is derived, in which the correlation coefficient is 0.81.

Key words: scavenging coefficient, collision coefficient, Huangshan mountain, thunderstorm, non-thunderstorm

CLC Number:

WANG Ying, ZHU Bin, KANG Hanqing, GAO Jinhui, JIANG Qi, LIU Xiaohui. Theoretical and observational study on below-cloud rain scavenging of aerosol particles[J]. Journal of University of Chinese Academy of Sciences, 2014, 31(3): 306-313.

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