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Tropical pathways, equatorial undercurrent variability and the 1998 La Niña
Author(s) -
Izumo Takeshi,
Picaut Joel,
Blanke Bruno
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl015073
Subject(s) - thermocline , upwelling , subtropics , geology , equator , oceanography , climatology , outcrop , ocean general circulation model , southern hemisphere , ocean gyre , ocean current , latitude , general circulation model , climate change , geomorphology , geodesy , fishery , biology
In the equatorial Pacific Ocean, the rapid transition from the 1997 El Niño to the 1998 La Niña was associated with an outcrop of cold water appearing at the surface around (0°, 125°W) end of May 1998. In a validated ocean general circulation model, the cold water of the outcrop appears to come from two pathways (one in each hemisphere) that connect the subtropics to the equatorial upwelling region through the western boundary currents and the Equatorial Undercurrent (EUC). The EUC and subtropics may have an influence on the rapid turn into La Niña in 1998. Large variations in transport (up to 60 × 10 6 m 3 s −1 ) and in transport‐weighted temperature (up to 3°C) of the EUC are observed in TAO moored data and in the model. The rapid variability of EUC transport and transport‐weighted temperature may interact with the long‐term variability of the thermocline circulation linking the subtropics to the equator.