UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-25 0:01
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Conference: Bucharest University Faculty of Physics 2003 Meeting


Section: Atmosphere and Earth Science; Environment Protection


Title:
Study of the dependence of effective radius of cloud droplets on aerosol type


Authors:
Simona Talpos, Sabina Stefan, Dorin Borsan


Affiliation:
University of Bucharest, Faculty of Physics, MG-11, Bucharest, Romania


E-mail


Keywords:


Abstract:
It is well known that the concentration and chemical characteristics of aerosol particles will directly affect the concentration and maximum size of cloud droplets, forming in an air mass. Hence, aerosol will affects the cloud optical thickness and albedo thus, cloud radiative forcing which is very important for studies of the global climate (Twomey 1974, 1979, Charlson et al. 1992, Bott, 2000). Cloud radiation is calculated in terms of two quantities: the liquid water and ice content, L (gm-3) and the effective cloud droplet radius. The latter parameter was defined by Hansen and Travis (1974) and analyzed, tested and used in a lot of papers (Martin et al. 1994, Lothman et al. 2000, Bott 2000). Effective radius is often assigned as a parameter dependent of the liquid water content (Fouquart et al.1990), or a constant, independent on the microphysical structure of the clouds.The goal of our work is to study the dependence on the microphysical aerosol properties. We choose four real aerosol size distributions for maritime and continental aerosol and assumed the CCN number concentration activated at the cloud base will be the same like the cloud droplets within cloud, when there is no input of extra CCN by entertainment or loss of droplets by drizzle. The results emphasize:effective radius depends on the aerosol size distribution and it is independent on liquid water content and number concentration of aerosol particles, accordingly with the observations of Albercht (1989); it depends on the aerosol type and increase with the increasing of maximum supersaturation in connection with the minimum radius of activated aerosol.