The poleward shift of South Atlantic Convergence Zone in recent decades

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, sugg...

Full description

Saved in:
Bibliographic Details
Published in:Climate dynamics 2019-03, Vol.52 (5-6), p.2545-2563
Main Authors: Zilli, Marcia T., Carvalho, Leila M. V., Lintner, Benjamin R.
Format: Article
Language:English
Subjects:
Analysis
Atmospheric circulation
Climate change
Climatology
Coasts
Convergence
Convergence zones
Daily precipitation
Drying
Earth and Environmental Science
Earth Sciences
Forecasts and trends
Geophysics/Geodesy
Monsoons
Oceanography
Oceans
Precipitation
Precipitation (Meteorology)
Precipitation trends
Precipitation variability
Rainfall intensity
South Atlantic Convergence Zone (SACZ)
Spatial variability
Spatial variations
Trends
Tropical climate
Troposphere
Wind
Winds
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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 (700 hPa) over the tropical Atlantic. These changes in circulation and moisture are likely related to the poleward expansion of the South Atlantic Subtropical High.
ISSN:0930-7575
1432-0894
DOI:10.1007/s00382-018-4277-1