Low-frequency climate variability in the Atlantic basin during the 20th century

Atmos. Sci. Let. (2010)
Published online in Wiley InterScience
(www.interscience.wiley.com) DOI : 10.1002/asl.265

Received : 20 May 2009
Revised : 17 January 2010
Accepted : 2 February 2010

Y. M. Tourre,1,2 S. Paz,3* Y. Kushnir2 and W. B. White4
1METEO-France, Toulouse, France
2LDEO of Columbia University, Palisades, NY, USA
3Department of Geography and Environmental Studies, University of Haifa, Haifa, Israel
4Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA

From joint sea surface temperature/sea level pressure (SST/SLP) EOF analyses, lowfrequency
variability modes are compared. The multi-decadal oscillation (MDO) changed
phases twice during the 20th century, with its north Atlantic SST patterns resembling
the Atlantic multi-decadal oscillation (AMO). The quasi-decadal oscillation (QDO) SST
patterns displayed a double tripole configuration over the entire Atlantic basin, leading
to tropical inter-hemispheric out-of-phase relationship. From the mid-1960s onward, while
SST anomalies were negative to the north (negative phases of MDO/AMO), the Sahelian
drought persisted with a weaker hurricane power dissipation index (PDI). During that
period, the QDO modulated the intensity of the Sahelian drought. Copyright  2010 Royal
Meteorological Society
Keywords : multi-decadal oscillation ; quasi-decadal oscillation ; Sahelian drought ; power
dissipation index