An Observed Connection between the North Atlantic Oscillation and the Madden–Julian Oscillation

Based on the bivariate Madden–Julian oscillation (MJO) index defined by Wheeler and Hendon and 25 yr (1979–2004) of pentad data, the association between the North Atlantic Oscillation (NAO) and the MJO on the intraseasonal time scale during the Northern Hemisphere winter season is analyzed. Time-lag...

Full description

Saved in:
Bibliographic Details
Published in:Journal of climate 2009-01, Vol.22 (2), p.364-380
Main Authors: Lin, Hai, Brunet, Gilbert, Derome, Jacques
Format: Article
Language:English
Subjects:
Atmosphere
Atmospheric circulation
Atmospheric models
Atmospherics
Climatology. Bioclimatology. Climate change
Composite indices
Convection
Earth, ocean, space
Exact sciences and technology
External geophysics
General circulation models
Geopotential height
Influence
Marine
Meteorology
Northern hemisphere
Oceans
Precipitation
Studies
Tropical climates
Tropical regions
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:Based on the bivariate Madden–Julian oscillation (MJO) index defined by Wheeler and Hendon and 25 yr (1979–2004) of pentad data, the association between the North Atlantic Oscillation (NAO) and the MJO on the intraseasonal time scale during the Northern Hemisphere winter season is analyzed. Time-lagged composites and probability analysis of the NAO index for different phases of the MJO reveal a statistically significant two-way connection between the NAO and the tropical convection of the MJO. A significant increase of the NAO amplitude happens about 5–15 days after the MJO-related convection anomaly reaches the tropical Indian Ocean and western Pacific region. The development of the NAO is associated with a Rossby wave train in the upstream Pacific and North American region. In the Atlantic and African sector, there is an extratropical influence on the tropical intraseasonal variability. Certain phases of the MJO are preceded by the occurrence of strong NAOs. A significant change of upper zonal wind in the tropical Atlantic is caused by a modulated transient westerly momentum flux convergence associated with the NAO.
ISSN:0894-8755
1520-0442
DOI:10.1175/2008jcli2515.1