Reduction of Tropical Cloudiness by Soot

Ackerman, A. S. ; Toon, O. B. ; Stevens, D. E. ; Heymsfield, A. J. ; Ramanathan, V.

Lawrence Livermore National Laboratory

关键词: Aerosols;    Clouds;    Pollution;    Indian Ocean;    Cloud Cover;   

DOI  :  10.2172/792796
RP-ID  :  UCRL-ID-138871
RP-ID  :  W-7405-Eng-48
RP-ID  :  792796

美国|英语

来源: UNT Digital Library

【 摘 要 】

Measurements and models show that enhanced aerosol concentrations can augment cloud albedo not only by increasing total droplet cross-sectional area, but also by reducing precipitation and thereby increasing cloud water content and cloud coverage. Aerosol pollution is expected to exert a net cooling influence on the global climate through these conventional mechanisms. Here we demonstrate an opposite mechanism through which aerosols can reduce cloud cover and thus significantly offset aerosol-induced radiative cooling at the top of the atmosphere on a regional scale. In model simulations the daytime clearing of trade cumulus is hastened and intensified by solar heating in dark haze (as found over much of the northern Indian Ocean during the northeast monsoon).