| Contributors | Affiliation | Role |
|---|---|---|
| Buesseler, Kenneth O. | Woods Hole Oceanographic Institution (WHOI) | Co-Principal Investigator |
| Chandler, Cynthia L. | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
Research Topic: Magnitude, Variability and Controls of Particulate Export in the Upper Ocean
We propose to examine, within existing JGOFS and related international data sets, the relationships between export and production and the special role that food web processes may have in controlling upper ocean export. The results thus far indicate that the relative rates of C fixation and C removal via sinking particles vary widely as a function of local food web dynamics (Buesseler, 1998). Given the large number of studies which now use 234Th as a proxy for POC export, we can start to compile global maps of POC export from the upper ocean. We will look directly at the full range of 234Th export data to assess trends between seasonal, episodic, or regional flux variability and a suite of physical and biological parameters. Because a significant portion of export may occur during short pulses or events, our goal is to help explain export variability in order to better model long-term mean export over larger time or space scales.
If common mechanisms can be found for the variations of production and export, these could then be incorporated into more reliable models of the global carbon cycle. While much of the ocean is characterized by low relative POC export, sites of high export are most often characterized by food webs dominated by large phytoplankton, in particular diatoms. If this result holds, models that attempt to predict new and export production from surface chlorophyll or production alone will not resolve the local carbon balance or allow one to model export controls. A mechanistic understanding of the underlying export processes is crucial to being able to incorporate this understanding into models, particularly if we desire to predict fluxes in future climate states.
We are closing in on the rate of exchange of CO2 between the ocean and atmosphere, a crucial flux for JGOFS. The partial pressure of CO2 at the surface is determined by thermodynamic effects on partial pressure and the balance of carbon fluxes into and away from the surface ocean. Determining the removal terms for carbon is one of the most challenging tasks; however, without measuring them correctly, our global models and global synthesis will always be tenuous. This is why understanding export is one of the highest priorities for SMP. We have to know what leaves the surface to balance against what is mixed into the surface or added by nitrogen fixation or atmospheric deposition. We also have to understand how this changes with time, ecosystem structure and physical regime. This proposal results in a global synthesis of the thorium derived export data. This will lead to a better understanding of carbon fluxes and parameterization of export that can be inserted into other models.
| Website | |
| Platform | Institution laboratories |
| Report | |
| Start Date | 1998-01-01 |
| End Date | 2005-10-01 |
| Description | Text from the U.S. JGOFS Implementation Plan for Synthesis and Modeling The Role of Oceanic Processes in the Global Carbon Cycle
[Full text at: http://usjgofs.whoi.edu/mzweb/smp/smpimp.htm]
The central objective of the U.S. JGOFS Synthesis and Modeling Project (SMP) is to synthesize knowledge gained from U.S. JGOFS and related studies into a set of models that reflect our current understanding of the ocean carbon cycle and its associated uncertainties. Emphasis will be given to processes that control partitioning of carbon among oceanic reservoirs and the implications of this partitioning for exchange between the ocean and atmosphere. To this end, the following specific SMP goals were adopted.
To synthesize our knowledge of inorganic and organic carbon fluxes and inventories, both natural and anthropogenic.
To identify and quantify the principal processes that control the partitioning of carbon among oceanic reservoirs and between the ocean and atmosphere on local and regional scales, with a view towards synthesis and prediction on a global scale.
To determine the mechanisms responsible for spatial and temporal variability in biogeochemical processes that control partitioning of carbon among oceanic reservoirs and between the ocean and atmosphere.
To assess and implement strategies for scaling data and models to seasonal, annual, and interannual time scales and to regional and global spatial scales.
To improve our ability to monitor and predict the role of oceanic processes in determining current and future partitionings of carbon between the ocean and atmosphere, and to evaluate uncertainties and identify gaps in our knowledge of these processes.
These goals will be addressed by three major program elements:
Global and regional mass balances: synthesis of improved estimates of natural and anthropogenic carbon inventories and of fluxes of carbon and related biologically active chemical substances.
Mechanistic controls of local carbon balances: identification and modeling of the principal processes that control within-ocean and ocean-atmosphere partitioning of carbon and related biologically active chemical substances, with a view towards developing regional and global syntheses and models.
Extrapolation, monitoring, and prediction: development and application of methods that will allow knowledge gained on small spatial and temporal scales to be scaled to seasonal, annual, and interannual time scales and to regional and global spatial scales; and development and application of methods that will improve our ability to monitor and predict the role of oceanic processes in determining the partitioning of carbon between the ocean and atmosphere and the resulting feedback to the climate system.
Implicit in this effort is the quantitative evaluation and estimation of associated uncertainties, as well as the identification of gaps in our knowledge that may significantly compromise monitoring and prediction of carbon partitioning. |
There were no cruises associated directly with the US JGOFS SMP. The SMP deployment refers to the project being deployed.
The Joint Global Ocean Flux Study (JGOFS) was an international scientific program devoted to the study of the ocean biogeochemistry of carbon and related elements and the linkages of the ocean with the global carbon cycle. The U.S. JGOFS program involved a decade long, intensive field effort that included: two on-going time-series stations off Hawaii and Bermuda; a series of process studies in the North Atlantic, Equatorial Pacific, Arabian Sea, and Southern Ocean; and a Global Ocean CO2 Survey in conjunction with the World Ocean Circulation Experiment (WOCE). The resulting ocean biogeochemical data sets, together with satellite ocean color data from the NASA Sea-viewing Wide Field-of-view Sensor (SeaWiFS), formed a unique, long-term resource for the ocean community. With the completion of the field phase in the late 1990s, the U.S. JGOFS initiated a final Synthesis and Modeling Project (SMP), to build on and integrate these data sets in order to address the key scientific themes of JGOFS:
Specifically, the central objective of the SMP was to synthesize knowledge gained from U.S. JGOFS and related studies into a set of models to reflect the current understanding of the ocean carbon cycle and its associated uncertainties (U.S. JGOFS, 1997). The SMP was tasked to address not only the processes that control carbon partitioning among oceanic reservoirs, but also the implications for ocean/atmosphere carbon exchange. Both data synthesis and modeling proposals were encouraged with an emphasis on coordinated interaction between the two. The major elements of the program included:
The SMP became a full fledged program with the funding of the first SMP awards in early 1998. Funding for SMP grants was provided by the National Science Foundation (NSF), the National Aeronautical and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and Department of Energy (DOE).
Specific projects within the SMP fell into two broad categories: data synthesis and extrapolation, and modeling. There was considerable (and necessary) overlap between the two, and the overview of the projects provided below is certainly a simplification of the collective efforts of the individual researchers (details on individual SMP grants can be found at http://usjgofs.whoi.edu/mzweb/syn-mod.htm). The scope and balance of the SMP was based on geographic region of study and investigation of biogeochemical processes.
The U.S. JGOFS SMP continued through the 2003-2004 time frame. As the program matured and specific initial projects were completed, the foci for the program was refined to emphasize both emerging new scientific directions and remaining unfinished elements of the original implementation plan. The SMP together with the U.S. JGOFS Steering Committee periodically assessed the program with regard to future priorities. During the active research phase, these are some of the topics identified as filling critical gaps for SMP science:
At the local to regional scale, a series of data synthesis and food web modeling investigations explored aspects of euphotic zone production, recycling, export, transport and remineralization, and sediment cycling using the JGOFS process and time-series data base and related data sets. Individual projects concentrated, for example, on subsets of the overall JGOFS data (e.g. bacteria, mesozooplankton, HPLC pigments). Related projects focused on the distribution and dynamics of planktonic functional groups (e.g. N2 fixers, diatoms, calcifiers). The eventual aim of many of these food web related studies was to extrapolate the findings to basin and global scale and/or to develop improved process-based parameterizations that could be incorporated into regional and global models.
One or more regional ecosystem modeling studies were undertaken for each of the following U.S. process/time-series study locations: Equatorial Pacific and Atlantic, Arabian Sea, Ross Sea, Bermuda, and North Atlantic. Additionally, there were four projects which concentrated on data synthesis and/or modeling for various continental margins: NW Atlantic margin, southern Caribbean, Cariaco Basin, and several coastal upwelling regions. The regional synthesis and modeling studies as well as some of the food web projects relied heavily on satellite data. Many SMP projects utilized satellite data, in particular SeaWiFS ocean color, as an integral part of both model evaluation and time/space extrapolation.
On the global perspective, over a dozen synthesis groups worked on the JGOFS/WOCE global CO2 survey data with good coverage for all of the carbon related parameters (DIC, alkalinity, 13C, 14C, nutrients, oxygen, pCO2, etc.). A coordinated global biogeochemical modeling effort was initiated as part of the international Ocean Carbon Model Intercomparison Project (OCMIP, http://www.ipsl.jussieu.fr/OCMIP/). As the name implies, this was an observation-based evaluation of some thirteen global ocean biogeochemical models of the natural and anthropogenic inorganic carbon system, biogeochemical fields (nutrients, oxygen), and related passive chemical tracers (e.g. CFCs, 14C, 3He).
Ocean Carbon & Biogeochemistry (OCB)
North American Carbon Program (NACP) Coastal Synthesis
The United States Joint Global Ocean Flux Study was a national component of international JGOFS and an integral part of global climate change research.
The U.S. launched the Joint Global Ocean Flux Study (JGOFS) in the late 1980s to study the ocean carbon cycle. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. As we studied ocean biogeochemistry, we learned that our simple views of carbon uptake and transport were severely limited, and a new "wave" of ocean science was born. U.S. JGOFS has been supported primarily by the U.S. National Science Foundation in collaboration with the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the Department of Energy and the Office of Naval Research. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP).
| Funding Source | Award |
|---|---|
| NSF Division of Ocean Sciences (NSF OCE) |