Premium
An eddy‐permitting coupled physical‐biological model of the North Atlantic: 1. Sensitivity to advection numerics and mixed layer physics
Author(s) -
Oschlies Andreas,
Garçon Veronique
Publication year - 1999
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/98gb02811
Subject(s) - advection , ocean gyre , upwelling , eddy diffusion , environmental science , mixed layer , ocean current , turbulence , climatology , ocean dynamics , diffusion , mesoscale meteorology , oceanography , atmospheric sciences , geology , subtropics , physics , meteorology , ecology , biology , thermodynamics
Physical influences on biological primary production in the North Atlantic are investigated by coupling a four‐component pelagic ecosystem model with a high‐resolution numerical circulation model. A series of sensitivity experiments demonstrates the important role of an accurate formulation of upper ocean turbulence and advection numerics. The unrealistically large diffusivity implicit in upstream advection approximately doubles primary production when compared with a less diffusive, higher‐order, positive‐definite advection scheme.This is of particular concern in the equatorial upwelling region where upstream advection leads to a considerable increase of upper ocean nitrate concentrations. Counteracting this effect of unrealistically large implicit diffusion by changes in the biological model could easily lead to misconceptions in the interpretation of ecosystem dynamics. Subgrid‐scale diapycnal diffusion strongly controls biological production in the subtropical gyre where winter mixing does not reach the nutricline. The parameterization of vertical viscosity is important mainly in the equatorial region where friction becomes an important agent in the momentum balance.