Abstract
Abstract. The performance of the coupled ocean–atmosphere component of the Brazilian Earth System Model version 2.5 (BESM-OA2.5) was evaluated in simulating the historical period 1850–2005. After a climate model validation procedure in which the main atmospheric and oceanic variabilities were evaluated against observed and reanalysis datasets, the evaluation specifically focused on the mean climate state and the most important large-scale climate variability patterns simulated in the historical run, which was forced by the observed greenhouse gas concentration. The most significant upgrades in the model's components are also briefly presented here. BESM-OA2.5 could reproduce the most important large-scale variabilities, particularly over the Atlantic Ocean (e.g., the North Atlantic Oscillation, the Atlantic Meridional Mode, and the Atlantic Meridional Overturning Circulation), and the extratropical modes that occur in both hemispheres. The model's ability to simulate such large-scale variabilities supports its usefulness for seasonal climate prediction and in climate change studies.
Highlights
Climate models, which have recently been expanded into Earth system models via inclusion of biogeochemical cycles, are key tools for investigating climate phenomena that significantly influence human societies (e.g., von Storch, 2010; Flato, 2011)
The atmospheric fields and sea ice concentration were from the Twentieth Century Reanalysis dataset version 2 (20CRv2; Compo et al, 2011) with a global horizontal resolution of 2◦ × 2◦ and 24 vertical levels; the precipitation dataset was obtained from the Global Precipitation Climatology Project version 2.2 Combined Precipitation Dataset (GPCP; Adler et al, 2003; Huffman et al, 2009) with a global horizontal resolution of 2.5◦ × 2.5◦ and from the Climate Prediction Center Merged Analysis of Precipitation (CMAP; Xie and Arkin, 1997), with a global horizontal resolution of 2.5◦ × 2.5◦
To compare Brazilian Earth System Model (BESM)-OA2.5 with the selected CMIP5 models, the grey shading represents the spread of the minimum and the maximum values of the yearly anomalies from the 11 models (Table 1)
Summary
Climate models, which have recently been expanded into Earth system models via inclusion of biogeochemical cycles, are key tools for investigating climate phenomena that significantly influence human societies (e.g., von Storch, 2010; Flato, 2011). Since 2008, the Brazilian climate community has been engaged in setting up the Brazilian Earth System Model (BESM; Nobre et al, 2013; Giarolla et al, 2015) This major scientific task has been carried out by Brazilian scientific institutions and highlights the critical need to produce reliable future climate projections and to understand their potential impact, over South America. The primary objective of this effort was to assemble the scientific expertise capable of developing and maintaining a state-of-the-art Earth system model Such an achievement would represent a significant step forward in establishing a scientific tool that can be used in different types of research activities. One of the fundamental aims of the BESM project is to participate in the Coupled Model Intercomparison Project’s sixth phase (CMIP6; Meehl et al, 2014)
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