Numerical
ocean carbon cycle models are the primary tools to predict the ocean's response
to increasing atmospheric CO2 concentration. So far most of these
have been based of physical components with geometric vertical levels. While
permitting an accurate computation of the horizontal pressure gradient driving
geostrophic flow, vertical discretization on z-levels leads to spurious
diapycnal mixing and upwelling. Isopycnic ocean models have an advantage over
those with geometric vertical layers in that their vertical coordinate mimics
the real structure of the water column as stratified layers of constant
density, and thus avoid artificial mixing and advection in the ocean interior.
Their disadvantages include the problem of massless layers, the necessity to
add a mixed layer model to adequately represent surface processes, and the
induction of a horizontal pressure gradient error by the sloping density
surfaces. Models with different vertical schemes thus complement each other and
can be used as one basis for an uncertainty assessment.
Author: K.M. Assmann, C. Heinze, H. Drange, M. Bentsen, and K. Lygre (karen dot assmann at bjerknes dot uib dot no)
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