On the sensitivity of ecosystem box model simulations on mixed-layer depth estimates

Eigenheer, Andreas; Kühn, Wilfried; Radach, Günther

doi:10.1016/0967-0637(96)00046-5

Cited by 15 publications

(2 citation statements)

References 32 publications

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“…The model therefore neglects horizontal transport processes and takes into account only vertical processes, i.e. advection () and diffusion (), which are considered the main driving forces of ecosystem dynamics in the upper ocean [ Eigenheer et al , 1996; Denman and Peña , 1999]. As in the models of Lefevre et al [2002] and Cropp et al [2004], vertical mixing in the current version of DMOS is parameterized using a prescribed turbulent diffusion coefficient ( kz , Table 1) following the approach used by Cropp et al [2004].…”

Section: Methodsmentioning

confidence: 99%

A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox

et al. 2008

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[1] A new one-dimensional model of DMSP/DMS dynamics (DMOS) is developed and applied to the Sargasso Sea in order to explain what drives the observed dimethylsulfide (DMS) summer paradox: a summer DMS concentration maximum concurrent with a minimum in the biomass of phytoplankton, the producers of the DMS precursor dimethylsulfoniopropionate (DMSP). Several mechanisms have been postulated to explain this mismatch: a succession in phytoplankton species composition towards higher relative abundances of DMSP producers in summer; inhibition of bacterial DMS consumption by ultraviolet radiation (UVR); and direct DMS production by phytoplankton due to UVR-induced oxidative stress. None of these hypothetical mechanisms, except for the first one, has been tested with a dynamic model. We have coupled a new sulfur cycle model that incorporates the latest knowledge on DMSP/DMS dynamics to a preexisting nitrogen/carbon-based ecological model that explicitly simulates the microbial-loop. This allows the role of bacteria in DMS production and consumption to be represented and quantified. The main improvements of DMOS with respect to previous DMSP/DMS models are the explicit inclusion of: solar-radiation inhibition of bacterial sulfur uptakes; DMS exudation by phytoplankton caused by solar-radiation-induced stress; and uptake of dissolved DMSP by phytoplankton. We have conducted a series of modeling experiments where some of the DMOS sulfur paths are turned ''off'' or ''on,'' and the results on chlorophyll-a, bacteria, DMS, and DMSP (particulate and dissolved) concentrations have been compared with climatological data of these same variables. The simulated rate of sulfur cycling processes are also compared with the scarce data available from previous works. All processes seem to play a role in driving DMS seasonality. Among them, however, solar-radiation-induced DMS exudation by phytoplankton stands out as the process without which the model is unable to produce realistic DMS simulations and reproduce the DMS summer paradox.

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Section: Methodsmentioning

confidence: 99%

A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox

et al. 2008

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“…The vertical physical dynamics of the mixed layer are a critical driving force determining ecosystem dynamics in the upper ocean [ Eigenheer et al , 1996]; by comparison, horizontal advection is believed to have little influence on mixed layer ecosystems [ Denman and Pena , 1999]. The mean irradiance field, controlled by the interaction of light penetration and the mixed layer depth, and the supply of nutrient into the mixed layer are important limiting factors on biological production [ Doney et al , 1996].…”

Section: Introductionmentioning

confidence: 99%

Modeling dimethylsulphide production in the upper ocean

Cropp

Norbury

Gabric

et al. 2004

Global Biogeochemical Cycles

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[1] Dimethylsulphide (DMS) is produced by upper ocean ecosystems and emitted to the atmosphere, where it may have an important role in climate regulation. Several attempts to quantify the role of DMS in climate change have been undertaken in modeling studies. We examine a model of biogenic DMS production and describe its endogenous dynamics and sensitivities. We extend the model to develop a one-dimensional version that more accurately resolves the important processes of the mixed layer in determining the ecosystem dynamics. Comparisons of the results of the one-dimensional model with an empirical relationship that describes the global distribution of DMS, and also with vertical profiles of DMS in the upper ocean measured at the Bermuda Atlantic Time Series, suggest that the model represents the interaction between the biological and physical processes well on local and global scales. Our analysis of the model confirms its veracity and provides insights into the important processes determining DMS concentration in the oceans.

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Future observational and modelling needs identified on the basis of the existing shelf data

Berlamont

Radach²,

Becker³

et al. 1996

Deutsche Hydrographische Zeitschrift

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2945 S u m m a ryNOWESP has compiled a vast quantity of existing data from the north-west European shelf. Such a focused task is without precedence. It is now highly recommended that one, or a few national and interna tional data centres or agencies should be chosen and properly supported by the E. U., where all available observational data, incl. the NOWESP data, are collected, stored, regularly updated by the providers of the data, and made available to the researchers. International agreement must be reached on the quality con trol procedures and quality standards for data to be stored in these data bases. Proper arrangements should be made to preserve the economic value of the data for their "owners" without compromising use of the data by researchers or duplicating data collecting efforts.The Continental Shelf data needed are concentration fields of temperature, salinity, nutrients, sus pended matter and chlorophyll, which can be called "climatological" fields. For this purpose at least one monthly survey on the whole European shelf is needed at least during five years, with a proper spatial reso lution, e. g. 1° by 1°, and at least in those areas where climatological data are now totally lacking. From the modelling point of view an alternative would be the availability of data from sufficiently representative fixed stations on the shelf, with weekly sampling for several years.It should be realized that there are hardly any data available on the shelf boundaries. Therefore, one should consider a European effort to set up a limited network of stations, especially at the shelf edge, where a limited, selected set of parameters is measured on a long-term basis (time series) for use in modelling and for interpreting long-term natural changes in the marine environment and changes due to human interfe rence (eutrophication, pollutants, climatic changes, biodiversity changes).The E. U. could foster coordination of nationally organized measuring campaigns in Europe. Methodologies should be promoted to collect areal distributed data sets through remote sensing (satel lite or aircraft-borne) techniques.The formulations of basic physics should be improved: turbulence must be simulated in a way that more closely represents nature. There is a need for a well validated, detailed shelf circulation model which repre sents the measured data properly during long-term simulations. Tides must always be included since they are important for mixing. A detailed North Atlantic ocean circulation model should be developed to provide proper boundary conditions at the shelf edge.The physics of exchanges at the shelf edges, between the ocean models and the shelf models should be studied and better formulated.Z u k ü n ftig e A n fo rd e ru n g e n an d ie M es su n g und M o d e llieru n g u n te r B e rü c k s ic h tig u n g v o rh a n d e n e r S ch e lfd ate n (Z u s a m m e n fa s s u n g ) Im Rahmen von NOWESP wurde eine immense Menge von Daten über den nordwesteuropäischen Schelf zusammengetragen, ein in dieser gezielten Form bish...

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On the sensitivity of ecosystem box model simulations on mixed-layer depth estimates

Cited by 15 publications

References 32 publications

A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox

A dynamic model of oceanic sulfur (DMOS) applied to the Sargasso Sea: Simulating the dimethylsulfide (DMS) summer paradox

Modeling dimethylsulphide production in the upper ocean

Future observational and modelling needs identified on the basis of the existing shelf data

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