Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century

In this paper, we demonstrate a global scale southward shift of the tropical rain belt during the latter half of the 20th century in observations and global climate models (GCMs). In rain gauge data, the southward shift maximizes in the 1980s and is associated with signals in Africa, Asia, and South...

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Bibliographic Details
Published in:Geophysical research letters 2013-06, Vol.40 (11), p.2845-2850
Main Authors: Hwang, Yen-Ting, Frierson, Dargan M. W., Kang, Sarah M.
Format: Article
Language:English
Subjects:
20th century
Aerosols
Atmospherics
Climate
climate change and variability
climate dynamics
clouds and aerosols
Computer simulation
Energy budgets
ENVIRONMENTAL SCIENCES
Geology
global climate models
Marine
Meteorology
Precipitation
Rain
Spreads
Sulfates
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Summary:In this paper, we demonstrate a global scale southward shift of the tropical rain belt during the latter half of the 20th century in observations and global climate models (GCMs). In rain gauge data, the southward shift maximizes in the 1980s and is associated with signals in Africa, Asia, and South America. A southward shift exists at a similar time in nearly all CMIP3 and CMIP5 historical simulations, and occurs on both land and ocean, although in most models the shifts are significantly less than in observations. Utilizing a theoretical framework based on atmospheric energetics, we perform an attribution of the zonal mean southward shift of precipitation across a large suite of CMIP3 and CMIP5 GCMs. Our results suggest that anthropogenic aerosol cooling of the Northern Hemisphere is the primary cause of the consistent southward shift across GCMs, although other processes affecting the atmospheric energy budget also contribute to the model‐to‐model spread. Key Points A southward shift of tropical rain in the 1980s is detected in observations Most CMIP3/5 GCMs simulate the shift, although less than observed Anthropogenic sulfate emissions cause most of the southward shift in the GCMs
ISSN:0094-8276
1944-8007
DOI:10.1002/grl.50502