The Representation of the Southern Annular Mode Signal in the Brazilian Earth System Model

Author(s)

Prado, Luciana F. ^[1] ; Wainer, Ilana ^[1] ; de Souza, Ronald B. ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Oceanog, Praca Oceanog 191, Cidade Univ, BR-05508120 Sao Paulo - Brazil

^[2] Inst Nacl Pesquisas Espaciais CPTEC INPE, Ctr Previsao Tempo & Estudos Climat, Div Modelagem Numer Sistema Terr, Rodovia Presidente Dutra Km 40, BR-12630000 Cachoeira Paulista, SP - Brazil

• Document type: Journal article
• Source: ATMOSPHERE; v. 12, n. 8 AUG 2021.
• Web of Science Citations: 0

Abstract

The Southern Annular Mode (SAM, also known as the Antarctic Oscillation-AAO) explains most of the climate variability in the Southern Hemisphere. A ring pattern in mean sea level pressure (MSLP) or 500 hPa geopotential height around Antarctica characterizes SAM. Differences of MSLP values between SH mid and high latitudes define positive and negative SAM phases with impacts on mean atmospheric circulation. Thus, investigating how different models represent SAM is of paramount importance, as it can improve their ability to describe or even predict most of the SH climate variability. Here we examine how the Brazilian Earth System Model (BESM) represents SAM's signal compared with observations, reanalysis, and other climate models contributing to the Coupled Modeling Intercomparison Project version 5 (CMIP5). We also evaluate how SAM relates to the South American surface temperature and precipitation and discuss the models' limitations and biases compared with reanalysis data. (AU)

• FAPESP's process: 18/14789-9 - Impact of volcanism on the South American Monsoon System and its relationship with the Atlantic Ocean sea surface temperature modes of variability
• Grantee: Ilana Elazari Klein Coaracy Wainer
• Support Opportunities: Regular Research Grants