Influence of horizontal model grid resolution on the simulated primary production in an embedded primary production model in the Norwegian Sea

Hansen, Cecilie; Samuelsen, Annette

doi:10.1016/j.jmarsys.2008.10.004

Cited by 23 publications

(20 citation statements)

References 26 publications

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“…The model results are also much smoother than the satellite data (Fig. 5), this is largely caused by the lack of eddy resolution (Hansen and Samuelsen, 2009). In addition the satellite images are not weekly averages, but a composite of incomplete satellite passes obtained that week.…”

Section: Discussionmentioning

confidence: 83%

“…That there is no significant improvement in the error statistics of COARSE compared to TOPAZ2 (not shown) supports this conclusion. Model resolution has been shown to impact the results of the biological model, but only when the resolution reaches the point when eddies are resolved (Hansen and Samuelsen, 2009). Therefore the first efforts will be towards finding alternative formulations that improve the model performance.…”

Section: Discussionmentioning

confidence: 99%

“…COARSE has 23 layers in the vertical and because this model was intended for coupling to biogeochemical models, the upper 5 layers were defined as z-levels to ensure good resolution in the upper part of the water column. The technical details of the spin-up of this model and the model drift are summarized in Hansen and Samuelsen (2009). The model was initialized with the Generalized Digital Environmental Model Data Base climatology (GDEM: Teague et al, 1990) and run from 1957 to the end of 2005.…”

Section: Physical Modelmentioning

confidence: 99%

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Impact of data assimilation of physical variables on the spring bloom from TOPAZ operational runs in the North Atlantic

Samuelsen¹,

Bertino²,

Hansen³

2009

Ocean Sci.

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Abstract.A reanalysis of the North Atlantic spring bloom in 2007 was produced using the real-time analysis from the TOPAZ North Atlantic and Arctic forecasting system. The TOPAZ system uses a hybrid coordinate general circulation ocean model and assimilates physical observations: sea surface anomalies, sea surface temperatures, and sea-ice concentrations using the Ensemble Kalman Filter. This ocean model was coupled to an ecosystem model, NORWECOM (Norwegian Ecological Model System), and the TOPAZ-NORWECOM coupled model was run throughout the spring and summer of 2007. The ecosystem model was run online, restarting from analyzed physical fields (result after data assimilation) every 7 days. Biological variables were not assimilated in the model. The main purpose of the study was to investigate the impact of physical data assimilation on the ecosystem model. This was determined by comparing the results to those from a model without assimilation of physical data. The regions of focus are the North Atlantic and the Arctic Ocean. Assimilation of physical variables does not affect the results from the ecosystem model significantly. The differences between the weekly mean values of chlorophyll are normally within 5-10% during the summer months, and the maximum difference of ∼20% occurs in the Arctic, also during summer. Special attention was paid to the nutrient input from the North Atlantic to the Nordic Seas and the impact of ice-assimilation on the ecosystem. The ice-assimilation increased the phytoplankton concentration: because there was less ice in the assimilation run, this increased both the mixing of nutrients during winter and the area where production could occur during summer. The forecast was also compared to remotely sensed chlorophyll, climatological nutrients, and in-situ data. The results show that the model reproduces a reCorrespondence to: A. Samuelsen (annette.samuelsen@nersc.no) alistic annual cycle, but the chlorophyll concentrations tend to be between 0.1 and 1.0 mg chla/m 3 too low during winter and spring and 1-2 mg chla/m 3 too high during summer. Surface nutrients on the other hand are generally lower than the climatology throughout the year.

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Physical Modelmentioning

confidence: 99%

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Impact of data assimilation of physical variables on the spring bloom from TOPAZ operational runs in the North Atlantic

Samuelsen¹,

Bertino²,

Hansen³

2009

Ocean Sci.

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“…We describe briefly this configuration, which corresponds to the coarse resolution one in Hansen and Samuelsen (2009).…”

Section: The Coupled Ocean Ecosystem Modelmentioning

confidence: 99%

“…Started from an already spun-up simulation at the date of 10 July 1997, the true state is generated by running the model without perturbation, while the ensemble is generated by running the same model with perturbations (more details about the generation of the ensemble come below). This simulation is issued from the work of Hansen and Samuelsen (2009) and corresponds to the results of a spin-up started in 1958. At this date the spring bloom is at a late stage and the concentration E. Simon and L. Bertino: Gaussian anamorphosis in a 3D ecosystem m 1997.…”

Section: Data Assimilation Experimentsmentioning

confidence: 99%

Application of the Gaussian anamorphosis to assimilation in a 3-D coupled physical-ecosystem model of the North Atlantic with the EnKF: a twin experiment

Simon¹,

Bertino²

2009

Ocean Sci.

121

104

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Abstract.We consider the application of the Ensemble Kalman Filter (EnKF) to a coupled ocean ecosystem model (HYCOM-NORWECOM). Such models, especially the ecosystem models, are characterized by strongly nonlinear interactions active in ocean blooms and present important difficulties for the use of data assimilation methods based on linear statistical analysis. Besides the non-linearity of the model, one is confronted with the model constraints, the analysis state having to be consistent with the model, especially with respect to the constraints that some of the variables have to be positive. Furthermore the non-Gaussian distributions of the biogeochemical variables break an important assumption of the linear analysis, leading to a loss of optimality of the filter. We present an extension of the EnKF dealing with these difficulties by introducing a nonlinear change of variables (anamorphosis function) in order to execute the analysis step in a Gaussian space, namely a space where the distributions of the transformed variables are Gaussian. We present also the initial results of the application of this non-Gaussian extension of the EnKF to the assimilation of simulated chlorophyll surface concentration data in a North Atlantic configuration of the HYCOM-NORWECOM coupled model.

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The carrying capacity of the seas and oceans for future sustainable food production: Current scientific knowledge gaps

Meer

Callier

Fabi

et al. 2023

Food and Energy Security

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The expected increase in global food demand, as a consequence of a rising and wealthier world population, and an awareness of the limits and drawbacks of modern agriculture, has resulted in a growing attention to the potential of the seas and oceans to produce more food. The capture production of presently exploited marine fish stocks and other species has more or less reached its maximum and can only be slightly improved by better management. This leaves four alternative options open to increase marine food production: (1) manipulating the entire food web structure via removal of high trophic level species to allow an increasing exploitation of low trophic level species, (2) harvesting so far unexploited stocks, such as various fish species from the mesopelagic zone of the ocean or the larger zooplankton species from polar regions, (3) low-trophic mariculture of seaweeds and herbivorous animals, and (4) restoration of impoverished coastal ecosystems or artificially increasing productivity by ecological engineering. In this paper, we discuss these four options and pay attention to missing scientific knowledge needed to assess their sustainability. To assess sustainability, it is a prerequisite to establish robust definitions and assessments of the biological carrying capacity of the systems, but it is also necessary to evaluate broader socio-economic and governance sustainability.

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Influence of horizontal model grid resolution on the simulated primary production in an embedded primary production model in the Norwegian Sea

Cited by 23 publications

References 26 publications

Impact of data assimilation of physical variables on the spring bloom from TOPAZ operational runs in the North Atlantic

Impact of data assimilation of physical variables on the spring bloom from TOPAZ operational runs in the North Atlantic

Application of the Gaussian anamorphosis to assimilation in a 3-D coupled physical-ecosystem model of the North Atlantic with the EnKF: a twin experiment

The carrying capacity of the seas and oceans for future sustainable food production: Current scientific knowledge gaps

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