Impact of the Equatorial Atlantic on the El Niño Southern Oscillation

Observations indicate that the Atlantic zonal mode influences El Niño Southern Oscillation (ENSO) in the Pacific, as already suggested in previous studies. Here we demonstrate for the first time using partial coupled experiments that the Atlantic zonal mode indeed influences ENSO. The partial coupli...

Full description

Saved in:
Bibliographic Details
Published in:Climate dynamics 2012-05, Vol.38 (9-10), p.1965-1972
Main Authors: Ding, Hui, Keenlyside, Noel S., Latif, Mojib
Format: Article
Language:English
Subjects:
Atmospheric circulation
Climatology
Climatology. Bioclimatology. Climate change
Earth and Environmental Science
Earth Sciences
Earth, ocean, space
Environmental aspects
Exact sciences and technology
External geophysics
Geophysics/Geodesy
Marine
Meteorology
Oceanography
Precipitation (Meteorology)
Southern oscillation
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:Observations indicate that the Atlantic zonal mode influences El Niño Southern Oscillation (ENSO) in the Pacific, as already suggested in previous studies. Here we demonstrate for the first time using partial coupled experiments that the Atlantic zonal mode indeed influences ENSO. The partial coupling experiments are performed by forcing the coupled general circulation model (ECHAM5/MPI-OM) with observed sea surface temperature (SST) in the Tropical Atlantic, but with full air-sea coupling allowed in the Pacific and Indian Ocean. The ensemble mean of a five member simulation reproduces the observational results well. Analysis of observations, reanalysis, and coupled model simulations all indicate the following mechanism: SST anomalies associated with the Atlantic zonal mode affect the Walker Circulation, driving westward wind anomalies over the equatorial Pacific during boreal summer. The wind stress anomalies increase the east-west thermocline slope and enhance the SST gradient across the Pacific; the Bjerknes positive feedback acts to amplify these anomalies favouring the development of a La Niña-like anomalies. The same mechanisms act for the cold phase of Atlantic zonal mode, but with opposite sign. In contrast to previous studies, the model shows that the influence on ENSO exists before 1970. Furthermore, no significant influence of the Tropical Atlantic on the Indian Monsoon precipitation is found in observation or model.
ISSN:0930-7575
1432-0894
DOI:10.1007/s00382-011-1097-y