Simultaneous data-based optimization of a 1D-ecosystem model at three locations in the North Atlantic Ocean: Part 1. Method and parameter estimates


Schartau, M. and Oschlies, A. (2003) Simultaneous data-based optimization of a 1D-ecosystem model at three locations in the North Atlantic Ocean: Part 1. Method and parameter estimates. Journal of Marine Research, 61, (6), 765-793. (doi:10.1357/002224003322981147).

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Description/Abstract

An optimization experiment is performed with a vertically resolved, nitrogen-based ecosystem model, composed of four state variables (NPZD-model): dissolved inorganic nitrogen (N), phytoplankton (P), herbivorous zooplankton (Z) and detritus (D). Parameter values of the NPZD-model are optimized while assimilating observations at three locations in the North Atlantic simultaneously, namely at the sites of the Bermuda Atlantic Time-Series Study (BATS; 31N 64W), of the North Atlantic Bloom Experiment (NABE; 47N 20W), and of Ocean Weather Ship-India (OWS-INDIA; 59N 19W). A method is described for a simultaneous optimization which effectively merges different types of observational data at distinct sites in the ocean. A micro-genetic algorithm is applied for the minimization of a weighted least square misfit function. The optimal parameter estimates are shown to represent a compromise among local parameter estimates that would be obtained from single-site optimizations at the individual locations. The optimization yields a high estimate of the initial slope parameter of photosynthesis (α), which is shown to be necessary to match the initial phases of phytoplankton growth. The estimate of α is well constrained by chlorophyll observations at the BATS and OWS-INDIA sites and likely compensates for a deficiency in the parameterization of light-limited growth. The optimization also points toward an enhanced recycling of organic nitrogen which is perceived from a high estimate for the phytoplankton mortality/excretion rate.

Item Type: Article
Related URLs:
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Divisions: University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 12709
Date Deposited: 01 Dec 2004
Last Modified: 27 Mar 2014 18:03
URI: http://eprints.soton.ac.uk/id/eprint/12709

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