American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 5426105 bytes)    Cited by

GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 17, NO. 2, 1035, doi:10.1029/2002GB001987, 2003

Eddy-driven sources and sinks of nutrients in the upper ocean: Results from a 0.1° resolution model of the North Atlantic

D. J. McGillicuddy Jr.

Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA


L. A. Anderson

Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA


S. C. Doney

Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA


M. E. Maltrud

Theoretical Fluid Dynamics, Los Alamos National Laboratory, Los Alamos, New Mexico, USA


Abstract

A nitrate-based model of new production is incorporated into eddy-resolving (0.1°) simulations of the North Atlantic. The biological model consists of light and nutrient limited production within the euphotic zone and relaxation of the nitrate field to climatology below. Sensitivity of the solutions to the parameters of the biological model is assessed in a series of simulations. Model skill is quantitatively evaluated with observations using an objective error metric; simulated new production falls within the range of observed values at several sites throughout the basin. Results from the “best fit” model are diagnosed in detail. Mean and eddying components of the nutrient fluxes are separated via Reynolds decomposition. In the subtropical gyre, eddy-driven vertical advection of nutrients is sufficient to overcome the mean wind-driven downwelling in the region and fuels a significant fraction of the annual new production in that area. In contrast, eddies constitute a net sink of nutrients in the subpolar gyre. Geostrophic adjustment to deep winter convection through mesoscale processes causes a net flux of nutrients out of the euphotic zone; the magnitude of this sink is sufficient to counterbalance the mean wind-driven upwelling of nutrients over much of the region. On the basis of these simulations it appears that the oceanic mesoscale has major impacts on nutrient supply to, and removal from, the euphotic zone.

Published 11 April 2003.

Index Terms: 4255 Oceanography: General: Numerical modeling; 4520 Oceanography: Physical: Eddies and mesoscale processes; 4572 Oceanography: Physical: Upper ocean processes; 4805 Oceanography: Biological and Chemical: Biogeochemical cycles (1615); 4845 Oceanography: Biological and Chemical: Nutrients and nutrient cycling.

Read Full Article (file size: 5426105 bytes)    Cited by

Citation: McGillicuddy, D. J., Jr., L. A. Anderson, S. C. Doney, and M. E. Maltrud (2003), Eddy-driven sources and sinks of nutrients in the upper ocean: Results from a 0.1° resolution model of the North Atlantic, Global Biogeochem. Cycles, 17(2), 1035, doi:10.1029/2002GB001987.