Stratospheric ozone depletion: a key driver of recent precipitation trends in South Eastern South America

• Published in: Climate dynamics Vol. 42; no. 7-8; pp. 1775 - 1792
• Main Authors: Gonzalez, Paula L. M., Polvani, Lorenzo M., Seager, Richard, Correa, Gustavo J. P.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2014; Springer; Springer Nature B.V
• Subjects: Air pollution; Analysis; Atmospheric chemistry; Atmospheric circulation; Climate change; Climate models; Climatology; Climatology. Bioclimatology. Climate change; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Environmental aspects; Equator; Exact sciences and technology; External geophysics; Geophysics/Geodesy; Greenhouse gases; Meteorology; Oceanography; Ozone; Ozone depletion; Ozone layer depletion; Precipitation (Meteorology); Rain; Stratosphere; South America; Brazil; ASW, South America; South America; Ozone depletion; Precipitation; 1970-1980; time series analysis; Multimodel; Coupled model; trend-surface analysis; Atmosphere model; General circulation models; atmospheric precipitation; Model output; 1960-1970; Impact study; Climate models; Ozone holes; Depletion; 1990-2000; stratosphere; 1980-1990
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-013-1777-x

On a hemispheric scale, it is now well established that stratospheric ozone depletion has been the principal driver of externally forced atmospheric circulation changes south of the Equator in the last decades of the 20th Century. The impact of ozone depletion has been felt over the entire hemisphere, as reflected in the poleward drift of the midlatitude jet, the southward expansion of the summertime Hadley cell and accompanying precipitation trends deep into the subtropics. On a regional scale, however, surface impacts directly attributable to ozone depletion have yet to be identified. In this paper we focus on South Eastern South America (SESA), a region that has exhibited one of the largest wetting trends during the 20th Century. We study the impact of ozone depletion on SESA precipitation using output from 6 different climate models, spanning a wide range of complexity. In all cases we contrast pairs of model integrations with and without ozone depletion, but with all other forcings identically specified. This allows for unambiguous attribution of the computed precipitation trends. All 6 climate models consistently reveal that stratospheric ozone depletion results in a significant wetting of SESA over the period 1960–1999. Taken as a whole, these model results strongly suggest that the impact of ozone depletion on SESA precipitation has been as large as, and quite possibly larger than, the one caused by increasing greenhouse gases over the same period.