|PSyDyn: a semi-spectral model of the dissolved-particulate exchanges: a preliminary stability analysis|
Athias, V.; Mazzega, P.; Ruiz-Pino, D.; Arraes, R.; Jeandel, C. (1998). PSyDyn: a semi-spectral model of the dissolved-particulate exchanges: a preliminary stability analysis, in: Dehairs, F.A. et al. (Ed.) Integrated Marine System Analysis. European Network for Integrated Marine System Analysis FWO Vlaanderen: Proceedings of the second network meeting (Brussels, May 29-31, 1997). pp. 299-321
In: Dehairs, F.A.; Elskens, M.; Goeyens, L. (Ed.) (1998). Integrated Marine System Analysis. European Network for Integrated Marine System Analysis FWO Vlaanderen: Proceedings of the second network meeting (Brussels, May 29-31, 1997). VUB. Laboratorium voor Analytische Chemie: Brussel. 376 pp., more
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VLIZ: Proceedings D 
|Document type: Conference paper|
Dissolved organic matter; Marine
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- Athias, V.
- Mazzega, P.
- Ruiz-Pino, D.
Most biogeochemical models that describe the dissolved-particulate exchanges in the water column are one plus one dimensional and based on a system of nonlinear coupled Partial Differential Equations (PDE). Until now, the rate constants of the processes that control these exchanges were estimated thanks to many hypotheses, and especially on the assumption of steady state. Nevertheless, many authors have underlined that such an assumption may not be verified. In that case, as the equations are both nonlinear and coupled, the solutions may adopt various dynamical behaviors (stationary, periodic, chaotic or intermittent). The inversion of such models poses theoretical problems and requires the characterization of the dynamical behavior of the model solutions. We propose here a semi-spectral model (PSyDyn), which is a general tool that applies to all the models based on a system of POE. It allows to turn the PDE into Ordinary Differential Equations (ODE), to which the Dynamical Systems Theory applies. It is then possible to consider characterizing the solutions dynamics, studying their stability, and identifying the bifurcations in response to alterations of the model parameters. We present a particular example, where PSyDyn is applied to the COLDO model. We realized preliminary numerical experiences, using in situ data of the aluminum distribution in the North-Western Mediterranean Sea. One of them allowed to calculate an Al residence time of 124 years, which is consistent with earlier studies. We also underscored a stationary behavior of the mass flux, and a bifurcation between a quasi-periodic and a stationary behavior of the mass flux, in response to an alteration of the disagregation rate.