South Atlantic Subtropical Anticyclone Associated with the Southern Annular Mode and Climate Impacts in Brazil

Abstract

The objective of this study is to investigate the precipitation and winds in Brazil associated with the South Atlantic subtropical anticyclone (SASA) in the different phases of the Southern Annular Mode (SAM). During the positive (negative) phase of the SAM, the SASA is positioned anomalously to the south (north), as well as the Intertropical Convergence Zone, contributing to the increase (reduction) of precipitation in the North (North and Northeast) region. Thus, we observed more intense (weak) winds in some areas of the south-Northeast, Southeast, and southern South -regions (much of the Northeast region and part of Tocantins and Minas Gerais) in the fall and winter (fall). Regarding precipitation, there is a reduction (increase) in south-central (southern-South region/ central-eastern) of Brazil between winter and summer (in spring and autumn/ summer). During the negative phase of the SAM, there is a reduction in the duration of the rainy season in the tropical region associated with a weakening of activity in the South Atlantic Convergence Zone and tropical convection. Autumn is the only season in which the strengthening of winds in the Northeast region can be used to complement hydroelectric power production due to precipitation deficit in both SAM phases.

Keywords:
South Atlantic subtropical anticyclone; Southern Annular Mode; precipitation; winds; Brazil