U.S. JGOFS SMP

U.S. JGOFS Synthesis & Modeling Project
David Glover Maureen Conte
A coupled epipelagic- meso/bathypelagic particle flux model for the Bermuda Atlantic Time-series Station (BATS)/Oceanic Flux Program (OFP) Site NSF OCE-0097288 06/01-05/04
PROJECT DESCRIPTION:	This proposal to the NSF U.S. JGOFS Synthesis and Modeling Program (SMP) will combine the observations of deep-water sediment traps (21+ years) at the Oceanic Flux Program (OFP), euphotic zone measurements (10+ years) at the Bermuda Atlantic Time-series Site (BATS), and historical meso/bathypelagi c zooplankton data with an ecosystem-based biogeochemical model of particle flux from the epipelagic to meso/bathypelagic zone. It is certain that ocean ecosystems will be affected by altered climate patterns, and an imperative exists to assess how the ocean and its biota naturally respond to climate and environmental forcing variables, and to model the ocean's response to possible climate change scenarios. Of fundamental concern is how changes in ocean remineralization will affect the magnitude of material fluxes through the water column. One of the major research trajectories of the U.S. JGOFS SMP is to investigate the mechanisms and rates of mid- to deep-water particle flux and remineralization. It is just these rates and mechanisms this proposal specifically seeks to elucidate. This study will, therefore, directly address desired research goals of the U.S. JGOFS SMP to increase our understanding of ocean variability over interannual and decadal time-scales and is of widespread interest and increasing relevance given the concerns about anthropogenic perturbations of global climate due to increases in greenhouse gases. Our overarching goal is to mechanistically connect euphotic zone processes with meso- and bathypelagic zone processes by means of a prognostic model that can be used to further our understanding of this unparalleled time-series and test hypotheses constrained by a battery of in situ data. In order to realize this goal we will derive a meso/bathypelagic ecosystem structure and use it to model the flux of biogeochemically active constituents (carbon, nitrogen and silica). The meso/bathypelagic portion of the model will be driven by a well established epipelagic model that couples an intermediately complex, yet robust, ecosystem model with a state-of-the-art physical upper ocean mixing model. The choice of driver is guided by our underlying hypothesis that the meso/bathypelagic activity inferred from the sediment trap data is a response to time-varying responses of the upper ocean ecosystem to events of meteorological scale. There is a remarkably strong covariance between the upper ocean particle flux at BATS and the deep particle flux measured by the OFP traps, as well as intense modification and strong convergence of the composition of the particle flux with depth to a invariant composition with respect to the magnitude of mass flux. These are the primary impetuses for development of a new model coupling recent physical-biological models of the surface ocean with particle flux and zooplankton reprocessing activities in the meso- and bathypelagic ocean. Numerical simulation of the biologically mediated repackaging of downward moving detritus will provide new insights into the mechanisms and rates of mid- to deep-water particle flux and remineralization. This is one of the major research trajectories of the U.S. JGOFS SMP. There are, however, other potential benefits likely to arise from this research. Prediction of the effect of changing climate forcing (e.g. interannual variability associated with ENSO, NAO) on deep particle flux is another area of research of import to U.S. JGOFS that this research will address. A combination of oceanographic and meteorological conditions spanning many space and time scales generally contributes to the observed signals. By mechanistically linking the upper and deep ocean with a model of the long-term Bermuda sediment trap records we can begin to deconvolve the multiple contributors to the deep flux patterns we observe.
DATA:	- no data submitted -
PUBLICATIONS:	- no publications listed -
RELATED PROJECTS:	- no related projects listed -
INVESTIGATOR INFORMATION:	David Glover Marine Chemistry and Geochemistry Woods Hole Oceanographic Institution Mail Stop #25 Woods Hole, MA 02543-1541 tel: 508-289-2656 fax: 508-457-2193 dglover@whoi.edu http://w3eos.whoi.edu/~david/dglover.html Maureen Conte Marine Chemistry and Geochemistry Woods Hole Oceanographic Institution Mail Stop #25 Woods Hole, MA 0254 tel: 508-289-3205 fax: 508-457-2193 mconte@whoi.edu