NSF Org:	OCE Division Of Ocean Sciences
Recipient:	UNIVERSITY OF MIAMI
Initial Amendment Date:	December 16, 1997
Latest Amendment Date:	December 6, 2000
Award Number:	9802062
Award Instrument:	Standard Grant
Program Manager:	Phillip R. Taylor OCE  Division Of Ocean Sciences GEO  Directorate for Geosciences
Start Date:	January 1, 1998
End Date:	December 31, 2001 (Estimated)
Total Intended Award Amount:	$51,480.00
Total Awarded Amount to Date:	$51,480.00
Funds Obligated to Date:	FY 1998 = $51,480.00
History of Investigator:	Rod Zika (Principal Investigator) rzika@rsmas.miami.edu Tsung-Hung Peng (Co-Principal Investigator)
Recipient Sponsored Research Office:	University of Miami 1251 MEMORIAL DR CORAL GABLES FL  US  33146-2509 (305)421-4089
Sponsor Congressional District:	27
Primary Place of Performance:	University of Miami 1251 MEMORIAL DR CORAL GABLES FL  US  33146-2509
Primary Place of Performance Congressional District:	27
Unique Entity Identifier (UEI):	KXN7HGCF6K91
Parent UEI:	VNZZYCJ55TC4
NSF Program(s):	BIOLOGICAL OCEANOGRAPHY, Chemical Oceanography
Primary Program Source:	app-0198
Program Reference Code(s):	1315, 1650, 4444, EGCH
Program Element Code(s):	165000, 167000
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

To identify and quantify the principal processes that control the partitioning of carbon among oceanic reservoirs and between the ocean and atmosphere on focal and regional scales, with a view towards synthesis and prediction on a global scale, is a specific goal of the U.S. JGOFS Synthesis and Modeling Project. As a contribution towards achieving this goal, Drs. Barber, Peng, Chai and Dugdale will develop an ecosystem model for the equatorial Pacific Ocean, with a focus on how silicate and iron affect new and export productivity and the partitioning of carbon between the atmosphere, surface ocean and deep ocean. The study will use an ecosystem model embedded in a state of the art general circulation model for the equatorial Pacific Ocean to investigate how new and export productivity responds to changing physical and chemical forcing. The domain of the model is between 30ÝS and 30ÝN, 120ÝE and 70ÝW, with real geometry and topography, but analysis will focus on the equatorial region from 5ÝN to 5ÝS. The recent upgrade of supercomputers at North Carolina Supercomputing Center (NCSC) (CrayT90) and Arctic Region Supercomputing Center (ARSC) (Cray YMP) and the award of several hundred hours of CPU time to Peng, Chai and Barber make it possible to embed an ecosystem model with modest complexity in a high resolution, three dimensional prognostic ocean model, and to conduct numerous experiments on the ecosystem model structure and parameters in a timely and efficient manner. Phase 1 of the project will modify an existing five compartment ecosystem model by adding three more compartments (silicate, diatoms and mesozooplanktonic grazers) following the approach of Dugdale et al. The preliminary objective of this three dimensional Si/N/light model is to reproduce High Nitrate Low Silicate Low Chlorophyll (HNLSLC) conditions. With size dependent growth rate responses in small phytoplankton and diatoms and varying grazing vulnerability, the role of new diatom production regulating on Si and Fe can be thoroughly investigated. Also in Phase 1, 2:CO2 and total alkalinity () ALK) will be added in order to calculate pCO2. The pre industrial atmospheric CO2 (280 1latm) will be used to hindcast air sea flux of CO2 in the equatorial Pacific. New production regulating on silicate should provide a more accurate calculation of CO2 compared to using nitrate as a regulating nutrient. In Phase 2 the effect of iron is added to the model making a, the initial slope of the photosynthesis vs. irradiance curve, a function of iron. The values of a are based on equatorial observations of natural and experimental iron additions. Independently, Ks for Si(OH4) is made a function of iron, an effect that involves only diatoms. The `balance to bloom` transition will be simulated with the two iron effects to reproduce the IronEx 1 and 2 phytoplankton responses to a transient iron addition. This modeling study will provide estimates of new and export productivity, and a formal description of Si and Fe as regulating mechanisms in the equatorial Pacific Ocean. When new and export productivity is modeled accurately and validated with JGOFS studies, it will possible to predict with increased confidence how climate change may alter, via biogenic export, maintenance of the air sea ApCO2 and hence the ocean's uptake and release of CO2. ½ñ &¬|óñú¡¬ñ &ñ¬ó? + ½»||úá¬ú<ññ ?|º+ñ¼¼á ñ Ñ|¬»á¬úñú ?|º+ñ¼¼á <ññ º¼(< áú«á+óñú &ᬼ ¿¿ <ññ ? º¼(< áú«á+óñú &ᬼ

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