Oceanic ventilation and biogeochemical cycling: Understanding the physical mechanisms that produce realistic distributions of tracers and productivity

Anand Gnanadesikan, John P. Dunne, Robert M. Key, Katsumi Matsumoto, Jorge Louis Sarmiento, Richard D. Slater, P. S. Swathi

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

Differing models of the ocean circulation support different rates of ventilation, which in turn produce different distributions of radiocarbon, oxygen, and export production. We examine these fields within a suite of general circulation models run to examine the sensitivity of the circulation to the parameterization of subgridscale mixing and surface forcing. We find that different models can explain relatively high fractions of the spatial variance in some fields such as radiocarbon, and that newer estimates of the rate of biological cycling are in better agreement with the models than previously published estimates. We consider how different models achieve such agreement and show that they can accomplish this in different ways. For example, models with high vertical diffusion move young surface waters into the Southern Ocean, while models with high winds move more young North Atlantic water into this region. The dependence on parameter values is not simple. Changes in the vertical diffusion coefficient, for example, can produce major changes in advective fluxes. In the coarse-resolution models studied here, lateral diffusion plays a major role in the tracer budget of the deep ocean, a somewhat worrisome fact as it is poorly constrained both observationally and theoretically.

Original languageEnglish (US)
Pages (from-to)1-17
Number of pages17
JournalGlobal Biogeochemical Cycles
Volume18
Issue number4
DOIs
StatePublished - Dec 1 2004

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

Keywords

  • Biogeochemical cycles
  • Particle export
  • Vertical exchange

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