Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Geophysical Research Letters NIL_45-NIL_49 2005 PAR00000704 ENG Geophysical Research Letters 0094-8276 CC:0002343643-0003 24 10.1029/2005GL024110 https://www.documentation.ird.fr/hor/PAR00000704 32 Horizon (IRD) 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 degrees W-180, 5 degrees N-5 degrees 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. 066 ; 021