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Biogeochemical impact of tropical instability waves in the equatorial Pacific
Author(s) -
Gorgues T.,
Menkes C.,
Aumont O.,
Vialard J.,
Dandonneau Y.,
Bopp L.
Publication year - 2005
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 - 10.1029/2005gl024110
Subject(s) - equator , biogeochemical cycle , advection , atmospheric sciences , phytoplankton , environmental science , oceanography , forcing (mathematics) , climatology , productivity , geology , nutrient , physics , chemistry , biology , latitude , ecology , environmental chemistry , geodesy , economics , thermodynamics , macroeconomics
Tropical Instability Waves (TIW) have been suggested to fertilize the equatorial Pacific in iron leading to enhanced ecosystem productivity. Using a coupled dynamical–biogeochemical model, we show that contrary to this suggestion, TIWs induce a decrease of iron concentration by 10% at the equator and by about 3% over the Wyrtki box [90°W–180, 5°N–5°S]. Chlorophyll decreases by 10% at the equator and 1% over the Wyrtki box. This leads to a decrease of new production up to 10% at the equator (4% over the Wyrtki box). TIW‐induced horizontal advection exports iron‐rich equatorial water to the north, but also brings iron‐depleted water to the equator leading to a net decrease in iron. Additional iron decrease is caused by TIW‐induced iron vertical diffusion. These two mechanisms are partly counter balanced by a decrease of iron biological uptake, driven by lower phytoplankton concentrations, and to a lesser extent by TIW‐induced iron vertical advection.