Sensitivity analysis of simple global marine biogeochemical models

Kriest, Iris, Oschlies, Andreas and Khatiwala, Samar (2012) Sensitivity analysis of simple global marine biogeochemical models Global Biogeochemical Cycles, 26 . GB2029. DOI 10.1029/2011GB004072.

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Abstract

This study presents results from 46 sensitivity experiments carried out with three structurally simple (2, 3, and 6 biogeochemical state variables, respectively) models of production, export and remineralization of organic phosphorus, coupled to a global ocean
circulation model and integrated for 3000 years each. The models’ skill is assessed via different misfit functions with respect to the observed global distributions of phosphate and
oxygen. Across the different models, the global root-mean square misfit with respect to
observed phosphate and oxygen distributions is found to be particularly sensitive to
changes in the remineralization length scale, and also to changes in simulated primary
production. For this metric, changes in the production and decay of dissolved organic
phosphorus as well as in zooplankton parameters are of lesser importance. For a misfit
function accounting for the misfit of upper-ocean tracers, however, production parameters and organic phosphorus dynamics play a larger role. Regional misfit patterns are
investigated as indicators of potential model deficiencies, such as missing iron limitation,
or deficiencies in the sinking and remineralization length scales. In particular, the gradient between phosphate concentrations in the northern North Pacific and the northern North Atlantic is controlled predominantly by the biogeochemical model parameters related to
particle flux. For the combined 46 sensitivity experiments performed here, the global
misfit to observed oxygen and phosphate distributions shows no clear relation to either
simulated global primary or export production for either misfit metric employed. However,
a relatively tight relationship that is very similar for the different model of different
structural complexity is found between the model-data misfit in oxygen and phosphate
distributions to simulated meso- and bathypelagic particle flux. Best agreement with the observed tracer distributions is obtained for simulated particle fluxes that agree most
closely with sediment trap data for a nominal depth of about 1000 m, or deeper.

Document Type: Article
Keywords: Biogeochemistry; Phosphorus; Sensitivity Analysis
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > SFB 754
OceanRep > SFB 754 > A2
OceanRep > SFB 754 > B1
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.1029/2011GB004072
ISSN: 0886-6236
Projects: SFB754, Future Ocean
Expeditions/Models:
Date Deposited: 18 Jun 2012 12:58
Last Modified: 26 Jan 2015 07:23
URI: http://eprints.uni-kiel.de/id/eprint/14320

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