Assessing the representation of South American monsoon features in Brazil and U.K. climate model simulations

Coelho, Caio A.S.; de Souza, Dayana C.; Kubota, Paulo Y.; Cavalcanti, Iracema F.A.; Baker, Jessica C.A.; Figueroa, Silvio N.; Firpo, Mári A.F.; Guimarães, Bruno S.; Costa, Simone M.S.; Gonçalves, Layrson J.M.; Bonatti, José P.; Sampaio, Gilvan; Klingaman, Nicholas P.; Chevuturi, Amulya ORCID: https://orcid.org/0000-0003-2815-7221; Andrews, Martin B.. 2022 Assessing the representation of South American monsoon features in Brazil and U.K. climate model simulations [in special issue: Climate Science for Service Partnership Brazil: collaborative research towards climate solutions in Brazil] Climate Resilience and Sustainability, 1 (1), e27. 23, pp. 10.1002/cli2.27

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Abstract/Summary

This paper assesses how well the CPTEC/INPE Brazilian Global Atmospheric Model (BAM-1.2) and the atmospheric component of the UK Met Office Hadley Centre Global Environment Model (HadGEM3-GC3.1) represent the main South American monsoon features. Climatological (1981–2010) ensemble means of Atmospheric Model Intercomparison Project (AMIP)-type climate simulations are evaluated. The assessment evaluated the models’ ability to represent the South America austral summer and winter precipitation contrast and associated circulation, key South American monsoon system elements, the association between south-east Brazil and South America precipitation, and climatological (1997/1998 to 2013/2014) distributions of rainy season onset and demise dates over south-east Brazil (15°S–25°S, 40°W–50°W) and the core monsoon region (10°S–20°S, 45°W–55°W). Despite some identified deficiencies, both models depict the monsoon region and represent the main features, including (1) the north-west–south-east precipitation band and associated ascending motion over central South America; (2) the upper-level Bolivian High and the north-east South America trough during the summer; (3) the lower-level South Atlantic and Pacific subtropical anti-cyclones and (4) the low-level jet east of the Andes. Both models represent upper-level divergence and lower-level convergence over the core monsoon region, and upper-level convergence and lower-level divergence over the Pacific and Atlantic anti-cyclones associated with the regional Walker circulation during the pre-monsoon (spring) and peak monsoon (summer) seasons. Convection over South America is weaker in BAM-1.2 than observed, consistent with continental precipitation deficit. The models reproduce the dipole-like precipitation pattern between south-east Brazil and south-eastern South America during the austral summer but overestimate these patterns spatial extent over the South Atlantic. Both models simulate the main observed climatological features of rainy season onset and demise dates for the two above defined investigated regions. HadGEM3 overestimates onset dates interannual variability. These results can contribute towards understanding climate and land-use change implications for environmental sustainability and for recommending climate adaptation strategies.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1002/cli2.27
UKCEH and CEH Sections/Science Areas:	Water Resources (Science Area 2017-)
ISSN:	2692-4587
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	climate model evaluation, rainy season onset and demise, South America monsoon
NORA Subject Terms:	Meteorology and Climatology
Date made live:	06 Dec 2021 09:51 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531496

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