The role of carbonaceous aerosols on short‐term variations of precipitation over North Africa

• Published in: Atmospheric science letters Vol. 17; no. 7; pp. 407 - 414
• Main Authors: Yoon, Jin‐Ho, Rasch, Philip J., Wang, Hailong, Vinoj, V., Ganguly, Dilip
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.07.2016; John Wiley & Sons, Inc; Royal Meteorological Society
• Subjects: Aerosol effects; aerosol indirect effect; Aerosols; Atmospheric precipitations; Atmospheric sciences; Biomass; carbonaceous; Climate models; cloud lifetime effect; Cloud properties; Clouds; Drought; ENVIRONMENTAL SCIENCES; Feedback; General circulation models; GEOSCIENCES; Hydrology; North Africa; Positive feedback; Precipitation; Rain; Rainfall; role; Sahel rainfall; Sea surface; Sea surface temperature; Seasons; short-term; Studies; Surface temperature; variations; United States > US; North Africa; Africa
• ISSN: 1530-261X; 1530-261X
• DOI: 10.1002/asl.672

Subtropical North Africa has been subject to extensive droughts in the late 20th century, linked to changes in the sea surface temperature (SST). However, climate models forced by observed SSTs cannot reproduce the magnitude of the observed rainfall reduction. Here, we propose aerosol indirect effects (AIE) as an important positive feedback mechanism. Model results are presented using two sets of sensitivity experiments designed to distinguish the role of aerosol direct/semi‐direct and indirect effects on regional precipitation. Changes in cloud properties due to the presence of carbonaceous aerosols are proposed as a key mechanism to explain the reduced rainfall over subtropical North Africa.