Indonesian throughflow control of the eastern equatorial Pacific biogeochemistry

Two model simulations were performed to address the influence of the Indonesian throughflow (ITF) on the biogeochemical state of the equatorial Pacific. A simulation where the ITF is open is compared with an experiment where it is closed, and it is first shown that the impacts on the physical circulation are consistent with what has been found in previous modelling studies. In terms of biochemistry, closing the ITF results in increased iron concentration at the origin of the Equatorial Undercurrent (EUC). But the 11Sv of water otherwise transferred to the Indian Ocean remain in the equatorial Pacific, which result in a 30 m deepening of the thermocline/ferricline in the eastern Pacific. This deepening decreases the iron concentration of the equatorial wind driven upwelled water and cancels the iron increase advected by the EUC. The iron decrease of the equatorial upwelled water leads to decrease primary production by 15% along the equator.

[1]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[2]  L. Bopp,et al.  Globalizing results from ocean in situ iron fertilization studies , 2006 .

[3]  L. Bopp,et al.  Biogeochemical impact of tropical instability waves in the equatorial Pacific , 2005 .

[4]  Francisco P. Chavez,et al.  From Anchovies to Sardines and Back: Multidecadal Change in the Pacific Ocean , 2003, Science.

[5]  Dimitris Menemenlis,et al.  Effects of the Indonesian Throughflow on the Pacific and Indian Oceans , 2002 .

[6]  D. Mackey,et al.  Iron in the western Pacific: a riverine or hydrothermal source for iron in the Equatorial Undercurrent? , 2002 .

[7]  Dongxiao Zhang,et al.  Slowdown of the meridional overturning circulation in the upper Pacific Ocean , 2002, Nature.

[8]  F. Chai,et al.  Meridional asymmetry of source nutrients to the equatorial Pacific upwelling ecosystem and its potential impact on ocean–atmosphere CO2 flux; a data and modeling approach , 2002 .

[9]  R. C. Dugdalea,et al.  Meridional asymmetry of source nutrients to the equatorial Pacific upwelling ecosystem and its potential impact on ocean – atmosphere CO 2 flux ; a data and modeling approach , 2002 .

[10]  P. Deschamps,et al.  Modeled and observed impacts of the 1997–1998 El Niño on nitrate and new production in the equatorial Pacific , 2001 .

[11]  C. McClain,et al.  Biogeochemical modelling of the tropical Pacific Ocean. I: Seasonal and interannual variability , 2001 .

[12]  D. Schrag,et al.  The role of the Indonesian Throughflow in equatorial Pacific thermocline ventilation , 1999 .

[13]  R. Murtugudde,et al.  Seasonal‐to‐interannual effects of the Indonesian throughflow on the tropical Indo‐Pacific Basin , 1998 .

[14]  A. Macdonald.  The global ocean circulation: a hydrographic estimate and regional analysis , 1998 .

[15]  M. Conkright.  World ocean atlas, 1998. Volume 11, Nutrients and chlorophyll of the Pacific Ocean , 1998 .

[16]  P. Delecluse,et al.  OPA 8.1 Ocean General Circulation Model reference manual , 1998 .

[17]  Stéphane Blain,et al.  Biomass, growth rates and limitation of Equatorial Pacific diatoms , 1997 .

[18]  K. Coale,et al.  Iron distributions in the equatorial Pacific: Implications for new production , 1997 .

[19]  P. Falkowski,et al.  Confirmation of iron limitation of phytoplankton photosynthesis in the equatorial Pacific Ocean , 1996, Nature.

[20]  J. S. Godfrey.  The effect of the Indonesian throughflow on ocean circulation and heat exchange with the atmosphere: A review , 1996 .

[21]  K. Johnson,et al.  Control of community growth and export production by upwelled iron in the equatorial Pacific Ocean , 1996, Nature.

[22]  Richard T. Barber,et al.  Origin and maintenance of a high nitrate condition in the equatorial Pacific , 1996 .

[23]  James W. Murray,et al.  A U.S. JGOFS process study in the equatorial Pacific (EqPac): Introduction , 1995 .

[24]  J. S. Godfrey,et al.  The role of Indonesian throughflow in a global ocean GCM , 1993 .

[25]  A. Gordon,et al.  Vertical Mixing in the Indonesian Thermocline , 1992 .

[26]  B. Jones,et al.  Hydrographic patterns and vertical mixing in the equatorial Pacific along 150°W , 1992 .

[27]  S. Fitzwater,et al.  The case for iron , 1991 .

[28]  E. Lindstrom,et al.  Source waters of the Pacific Equatorial Undercurrent , 1989 .

[29]  John J. Walsh,et al.  Herbivory as a factor in patterns of nutrient utilization in the sea1 , 1976 .