Open AccessDoes a dipole mode really exist in the South Atlantic Ocean?
Author(s) -
Nnamchi Hyacinth C.,
Li Jianping,
Anyadike Raymond N. C.
Publication year - 2011
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010jd015579
Subject(s) - anomaly (physics) , climatology , sea surface temperature , precipitation , mode (computer interface) , indian ocean dipole , oceanography , tropical atlantic , atmosphere (unit) , geology , ocean current , environmental science , geography , meteorology , physics , condensed matter physics , computer science , operating system
This study investigates the existence of a dipole mode in the sea surface temperatures (SST) over the South Atlantic Ocean (SAO), using observational and reanalysis data sets from 1950 to 2008. Our results demonstrate that an opposite SST mode, the SAO dipole (SAOD) occurs in the SAO as the anomalous surface waters in the northeastern part; that is, the Atlantic Niño sector and the southwestern part off the Argentina‐Uruguay‐Brazil coast are consistently anticorrelated in all months. A typical SAOD episode has a life cycle of about eight months, although the peak intensity in which the SST anomalies are evidently coupled to atmospheric circulation and precipitation anomaly fields lasts for four months during the austral winter (May–August). This coupled atmosphere‐ocean interaction mechanism appears to be unique, distinct from the classical Atlantic Niño and independent of the direct influence of the Pacific Ocean‐based El Niño or global SST variability. The SAOD may provide a useful framework for investigating climate variability and for improved predictions especially over parts of Africa and the Americas, and some preliminary results are already indicated, e.g., the SAOD is widely related to precipitation anomalies in these regions particularly during the austral winter.