Analysis of precipitation climatology simulated by high resolution coupled global models over the South America
October 11th, 2012
Maria de Souza Custódio, Rosmeri Porfírio da Rocha, Pier Luigi Vidale
Released: October 11, 2012
Analysis of precipitation climatology simulated by high resolution coupled global models over the South America
Maria de Souza Custódio1), Rosmeri Porfírio da Rocha1), Pier Luigi Vidale2)
1) Department of Atmospheric Sciences, University of São Paulo
2) Department of Meteorology, University of Reading and National Centre for Atmospheric Science (NCAS), UK
The results of coupled high resolution global models (CGCMs) over South America are discussed. HiGEM1.2 and HadGEM1.2 simulations, with horizontal resolution of ~90 and 135 km, respectively, are compared. Precipitation estimations from CMAP (Climate Prediction Center—Merged Analysis of Precipitation), CPC (Climate Prediction Center) and GPCP (Global Precipitation Climatology Project) are used for validation. HiGEM1.2 and HadGEM1.2 simulated seasonal mean precipitation spatial patterns similar to the CMAP. The positioning and migration of the Intertropical Convergence Zone and of the Pacific and Atlantic subtropical highs are correctly simulated by the models. In HiGEM1.2 and HadGEM1.2, the intensity and locations of the South Atlantic Convergence Zone are in agreement with the observed dataset. The simulated annual cycles are in phase with estimations of rainfall for most of the six regions considered. An important result is that HiGEM1.2 and HadGEM1.2 eliminate a common problem of coarse resolution CGCMs, which is the simulation of a semiannual cycle of precipitation due to the semiannual solar forcing. Comparatively, the use of high resolution in HiGEM1.2 reduces the dry biases in the central part of Brazil during austral winter and spring and in most part of the year over an oceanic box in eastern Uruguay.
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