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Equatorial nutrient trapping in biogeochemical ocean models: The role of advection numerics
Author(s) -
Oschlies Andreas
Publication year - 2000
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 - 10.1029/1999gb001217
Subject(s) - advection , biogeochemical cycle , upwelling , nutrient , environmental science , oceanography , biogeochemistry , dissolved organic carbon , geology , chemistry , environmental chemistry , physics , organic chemistry , thermodynamics
The unrealistic accumulation of nutrients below the equatorial upwelling regions, termed “nutrient trapping” by Najjar et al. [1992], has been a major problem of first‐generation oceanic carbon cycle models. Suggestions to eliminate this modeling problem include the consideration of dissolved organic nutrients and improvements to the underlying circulation field. This study shows that neither of these suggestions can be complete without a careful investigation of advection numerics. Using a high‐resolution coupled biological‐physical model of the North and equatorial Atlantic, it is demonstrated for standard central‐difference advection (if a too coarse vertical resolution is used) as well as for upstream advection that numerical artifacts alone can lead to a systematic overestimation (by as much as 50%) of simulated subsurface nutrient concentrations in the equatorial upwelling region. A corollary of these results is that without a critical examination of the underlying advection numerics, nutrient trapping alone can no longer present an unchallenged justification for including dissolved organic matter in biogeochemical ocean models.