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Title

Impact of projected SST changes on summer rainfall in southeastern South America

Publication Year

2013

Author(s)
  • Junquas, C.
  • Vera, C. S.
  • Li, L.
  • Le Treut, H.
Source
CLIMATE DYNAMICS Volume: 40 Issue: 7-8 Pages: 1569-1589 Published: 2013
ISSN
0930-7575
Abstract

Recent studies have shown that global warming and associated sea-surface temperature (SST) changes may trigger an important rainfall increase in southeastern South America (SESA) during the austral summer (December-January-February, DJF). The goal of this paper is to provide some insight into processes which may link global and SESA changes. For this purpose, a two-way nesting system coupling interactively the regional and global versions of the LMDZ4 atmospheric model is used to study the response to prescribed SST changes. The regional model is a variable-grid version of the global model, with a zoom focused over South America. An ensemble of simulations forced by distinct patterns of DJF SST changes has been carried out using a decomposition of full SST changes into their longitudinal and latitudinal components. The full SST changes are based on projections for the end of the twenty-first century from a multi-model ensemble of WCRP/CMIP3. Results confirm the presence of a major rainfall dipole structure, characterized by an increase in SESA and a decrease in the South Atlantic Convergence Zone region. Rainfall changes found in the WCRP/CMIP3 models are largely explained as a response of this dipole structure to the zonally-asymmetric (or longitudinal) component of SST changes. The rainfall response to the zonal-mean (or latitudinal) SST changes (including the global warming signal itself) shows an opposite contribution. The processes explaining the role of zonally-asymmetric SST changes involve remote effects of SST warming over the equatorial Indian and Pacific oceans inducing an atmospheric wave-train extended across the South Pacific into South America.

Author Keyword(s)
  • South America climate
  • Rainfall changes
  • Two-way nesting system
  • Sea surface temperature projections
  • Climate change
KeyWord(s) Plus
  • SURFACE TEMPERATURE ANOMALIES
  • LOW-LEVEL CIRCULATION
  • EL-NINO
  • TROPOSPHERIC CIRCULATION
  • INTERANNUAL VARIABILITY
  • TROPICAL PRECIPITATION
  • ATMOSPHERIC MODEL
  • CLIMATE
  • MONSOON
  • ANDES
ESI Discipline(s)
  • Geosciences
Web of Science Category(ies)
  • Meteorology & Atmospheric Sciences
Adress(es)

[Junquas, C.; Li, L.; Le Treut, H.] UPMC, CNRS, Lab Meteorol Dynam, Inst Pierre Simon Laplace, Paris, France; [Junquas, C.; Vera, C. S.] UBA, CONICET, CIMA, DCAO,FCEN,UMI,IFAECI,CNRS, Buenos Aires, DF, Argentina

Reprint Adress

Junquas, C (reprint author), UPMC, CNRS, Lab Meteorol Dynam, Inst Pierre Simon Laplace, Paris, France.

Country(ies)
  • Argentina
  • France
CNRS - Adress(es)
  • Institut Pierre-Simon Laplace (IPSL), FR636
  • Laboratoire de météorologie dynamique (LMD), UMR8539
Accession Number
WOS:000317075700001
uid:/J423L842
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