Diagnostics of diapycnal diffusion in z-level ocean models. Part II: 3-Dimensional OGCM.

Getzlaff, Julia, Nurser, George and Oschlies, Andreas (2012) Diagnostics of diapycnal diffusion in z-level ocean models. Part II: 3-Dimensional OGCM. Ocean Modelling, 45-46 . pp. 27-36. DOI 10.1016/j.ocemod.2011.11.006.

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Abstract

We present a robust method for diagnosing total diapycnal diffusivities, i.e. explicitly applied plus numerically induced diffusivities, from tracer release experiments in numerical z-level models. To this extent, numerical experiments differing only in the advection scheme used (CTRD using 2nd order centred differences, UPWIND using the upwind/upstream advection scheme, QUICK using the quicker advection scheme after Farrow and Stevens (1995) and FCT after Gerdes et al. (1991)) are analysed and compared. To obtain regionally resolved estimates of diapycnal diffusivities, individual inert dye tracers are released in dynamically different regions of a North Atlantic model, namely (i) in the interior of the subtropical gyre and (ii) in the western boundary current. Diagnosed diffusivities are robust with respect to changes in temporal and spatial sampling of the simulated dye tracer for both advection schemes and for both regions. The numerically induced diffusivity is generally positive, but can become negative for centred differences advection numerics after several months of simulated tracer dispersion.

Document Type: Article
Keywords: Physical Oceanography; Oceanography; Biogeochemistry; Diapycnal diffusion; Numerical mixing; z-Level models
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
Kiel University
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Projects: Future Ocean
Date Deposited: 10 May 2012 13:44
Last Modified: 23 Sep 2019 18:18
URI: https://oceanrep.geomar.de/id/eprint/14272

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