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Journal Articles Geophysical Research Letters Year : 2005

Biogeochemical impact of tropical instability waves in the equatorial Pacific

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Abstract

Tropical Instability Waves (TIW) have been suggested to fertilize the equatorial Pacific in iron leading to enhanced ecosystem activity. Using a coupled dynamical-biogeochemical model, we show that contrary to this suggestion, TIWs induce a decrease of iron concentration by 20% at the equator and by about 3% over the "TIW box" [90°W- 180, 5°N-5°S]. Chlorophyll decreases by 10% at the equator and 1% over the "TIW box". This leads to a decrease of new production up to 10% at the equator (4% over the "TIW box"). TIW-induced horizontal advection brings more iron-depleted water to the equator than it exports iron-rich equatorial water to the north. 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 weaker phytoplankton concentration, and to a lesser extend by TIW- induced iron vertical advection.
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Dates and versions

hal-00122343 , version 1 (26-03-2007)

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Thomas Gorgues, Christophe E. Menkès, Olivier Aumont, Jérôme Vialard, Yves Dandonneau, et al.. Biogeochemical impact of tropical instability waves in the equatorial Pacific. Geophysical Research Letters, 2005, 32, pp.L24615. ⟨10.1029/2005GL024110⟩. ⟨hal-00122343⟩
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