The poleward shift of South Atlantic Convergence Zone in recent decades

Author(s)

Zilli, Marcia T. ^[1] ; Carvalho, Leila M. V. ^{[2, 1]} ; Lintner, Benjamin R. ^[3]

Affiliation

^[1] Univ Calif Santa Barbara, Dept Geog, 1832 Ellison Hall, Santa Barbara, CA 93106 - USA

^[2] Univ Calif Santa Barbara, Earth Res Inst, Santa Barbara, CA 93106 - USA

^[3] Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ - USA

• Document type: Journal article
• Source: Climate Dynamics; v. 52, n. 5-6, p. 2545-2563, MAR 2019.
• Web of Science Citations: 5

Abstract

During austral summer (December-January-February or DJF), intense precipitation over central-eastern Brazil is modulated by the South American Monsoon System and the South Atlantic Convergence Zone (SACZ). Previous studies identified spatial variability in precipitation trends over this region, suggestive of a poleward shift of the SACZ in recent years. To identify underlying mechanisms associated with changes in the precipitation intensity and position of the SACZ, decadal averages of observed precipitation and the mean state of the atmosphere and ocean during three different periods from 1979 to 2014 are compared. Results show evidence of decreasing (increasing) average daily precipitation along the equatorward (poleward) margin of the climatological SACZ, likely related to a poleward shift of the convergence zone. Precipitation reduction along the equatorward margin of the SACZ is associated with weakening of the poleward winds along the eastern Brazilian coast and drying of low-to-mid troposphere (700hPa) over the tropical Atlantic. These changes in circulation and moisture are likely related to the poleward expansion of the South Atlantic Subtropical High. (AU)

• FAPESP's process: 08/58101-9 - Impact of the Southwestern Atlantic Ocean on South American climate for the 20th and 21st centuries
• Grantee: Tercio Ambrizzi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants