U.S. JGOFS SMP

U.S. JGOFS Synthesis & Modeling Project
R. M. Key L. I. Gordon C. L. Sabine N. Gruber C. W. Mordy
Determination of the Redfield remineralization ratios based on neutral surface analysis of the new global data set NSF OCE-9819144 / OCE-9903391 06/99 - 05/02
PROJECT DESCRIPTION:	Synthesis of primary nutrients by marine organisms and subsequent remineralization of organic matter is frequently represented by Equation 1 (eq. 1) where the coefficients are known as the "Redfield" ratios. Redfield ratios have been particularly useful in estimating the utilization of one nutrient from another and in deriving dynamically passive conservative tracers such as "NO" and "PO". More recently PO₄, C and N* have been used to study air-sea oxygen fluxes, large scale mixing problems, anthropogenic CO₂ and nitrogen biogeochemistry. The value of the ratios and their large scale variability are also important because they are a critical component in the application of computer models to study ocean biogeochemistry and global climate change. The traditional P:N:C_org Redfield ratios of 1:16:106 were based on planktonic decomposition studies. Recent studies have reevaluated the ratios. Significant disagreement still exists, however. In large part the disagreement stems from various weaknesses in the approaches and in the overall quality and quantity of the data sets used. The goal of this project is to redetermine the Redfield ratios of remineralization. Specific improvements over previous efforts include the availability of a new global high quality nutrient data set and application of an optimal multi-parameter technique to determine endpoints. The technique will be applied on approximately 20 neutral density layers in each ocean basin. A significant improvement over previous work will be the inclusion of the recently completed global CO₂ survey results along with the new nutrient data. In the analysis corrections for the potential bias caused by anthropogenic CO₂ invasion, nitrogen fixation and denitrification will be made. Preliminary investigations have demonstrated that small systematic offsets exist in the nutrient data. Therefore, prior to calculation of the Redfield ratios, a comprehensive global calibration of the nitrate, phosphate and silicate data sets will be completed. The analytical procedures for this calibration have already been developed. The results of this work will directly address specific research trajectory elements 1 and 2 outlined in the JGOFS SMP implementation plan and will benefit several collaborative efforts.
DATA:	GLODAP (GLobal Ocean Data Analysis Project) provides many datasets from this project via (anthropogenic carbon, delta CO2 1995-1978, total alkalinity, total carbon)
PUBLICATIONS:	Keller, K., R.D. Slater, M. Bender, R.M. Key. (submitted) Possible biological or physical explanations for decadal scale trends in North Pacific nutrient concentrations and oxygen utilization. DSR II, First Special Issue of the U.S. JGOFS Synthesis and Modeling Project. Additional publications related to this project are listed via http://geoweb.princeton.edu/bigscience/GLODAP/nutrients/GLODAP.ref.html
RELATED PROJECTS:	Gruber "Analyzing and modeling interannual to decadal variability in the carbon cycle of the subtropical and subpolar gyres." Najjar; Doney; Key; Sabine; Sarmiento; Caldeira "Evaluation and intercomparison of three-dimensional marine carbon cycle models" Sabine; Key; Feely; Bullister; Millero; Wanninkhof; Peng; Kozyr "Synthesis and interpretation of the NOAA/DOE global CO2 survey data" Gruber; Sabine; Sonnerup; Bullister; Key "Global Assessment and Synthesis of Data Based Estimates of Anthropogenic CO2 in the Ocean"
INVESTIGATOR INFORMATION:	Robert M. Key Program in Atmospheric and Ocean Sciences Department of Geosciences, Guyot Hall Princeton University Princeton, NJ 08544-1003 tel: (609) 258-3595 fax: (609) 258-1274 key@princeton.edu http://geoweb.princeton.edu/staff/Key/Index.html Louis I. Gordon College of Oceanic & Atmospheric Sciences Oregon State University 104 Ocean Admin Bldg Corvallis, OR 97331-5503 tel: (541) 737-2161 fax: (541) 737-2064 lgordon@oce.orst.edu http://www.oce.orst.edu/faculty/gordon.html Christopher Sabine NOAA/PMEL 7600 Sandpoint Way NE Seattle, WA 98115 tel: (206) 526-4809 fax: (206) 526-6744 sabine@pmel.noaa.gov http://www.pmel.noaa.gov/~sabine/index.html Nicolas Gruber Inst. Geophysics and Planetary Physics & Dept Atmos. Sci. University of California, Los Angeles 5853 Slichter Hall Los Angeles, CA 90095-1567 tel: 310-825-4772 fax: 310-206-3051 ngruber@igpp.ucla.edu http://www.atmos.ucla.edu/~gruber/people/gruber/gruber_fs_overview.htm C.W. Mordy NOAA/PMEL R/E/PM 7600 Sand Point Way N.E. Seattle, WA 98115-0070 tel: (206) 526-6870 fax: (206) 526-6744 mordy@pmel.noaa.gov