Intraseasonal Variability Associated with Summer Precipitation Over South America Simulated by 14 IPCC AR4 Coupled GCMs
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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This study evaluates the intraseasonal variability associated with summer precipitation over South America in 14 coupled general circulation models GCMs participating in the Intergovernmental Panel on Climate Change IPCC Fourth Assessment Report AR4. Eight years of each models twentieth-century climate simulation are analyzed. Two dominant intraseasonal bands associated with summer precipitation over South America are focused on the 40- and the 22 day band. The results show that in the southern summer November-April, most of the models underestimate seasonal mean precipitation over central-east Brazil, northeast Brazil, and the South Atlantic convergence zone SAC2, while the Atlantic intertropical convergence zone ITCZ is shifted southward of its observed position. It is found that models with some form of moisture convective trigger tend to produce large variances for the intraseasonal bands.