scholarly journals An isopycnic ocean carbon cycle model

2009 ◽  
Vol 2 (2) ◽  
pp. 1023-1079 ◽  
Author(s):  
K. M. Assmann ◽  
M. Bentsen ◽  
J. Segschneider ◽  
C. Heinze
Keyword(s):  
Carbon Cycle ◽  
Global Ocean ◽  
System Modelling ◽  
Surface Boundary ◽  
Cycle Model ◽  
Biological Production ◽  
Carbon Cycle Model ◽  
Export Production ◽  
Sensitivity Studies ◽  
Ocean Carbon

Abstract. The carbon cycle is a major forcing component in the global climate system. Modelling studies aiming to explain recent and past climatic changes and to project future ones thus increasingly include the interaction between the physical and biogeochemical systems. Their ocean components are generally z-coordinate models that are conceptually easy to use but that employ a vertical coordinate that is alien to the real ocean structure. Here we present first results from a newly developed isopycnic carbon cycle model and demonstrate the viability of using an isopycnic physical component for this purpose. As expected, the model represents interior ocean transport of biogeochemical tracers well and produces realistic tracer distributions. Difficulties in employing a purely isopycnic coordinate lie mainly in the treatment of the surface boundary layer which is often represented by a bulk mixed layer. The most significant adjustments of the biogeochemical code for use with an isopycnic coordinate are in the representation of upper ocean biological production. We present a series of sensitivity studies exploring the effect of changes in biogeochemical and physical processes on export production and nutrient distribution. Apart from giving us pointers for further model development, they highlight the importance of preformed nutrient distributions in the Southern Ocean for global nutrient distributions. Use of a prognostic slab atmosphere allows us to assess the effect of the changes in export production on global ocean carbon uptake and atmospheric CO2 levels. Sensitivity studies show that iron limitation for biological particle production, the treatment of light penetration for biological production, and the role of diapycnal mixing result in significant changes of modelled air-sea fluxes and nutrient distributions.

scholarly journals An isopycnic ocean carbon cycle model

2010 ◽  
Vol 3 (1) ◽  
pp. 143-167 ◽  
Author(s):  
K. M. Assmann ◽  
M. Bentsen ◽  
J. Segschneider ◽  
C. Heinze
Keyword(s):  
Carbon Cycle ◽  
Particle Production ◽  
Global Climate ◽  
System Modelling ◽  
Surface Boundary ◽  
Cycle Model ◽  
Nutrient Distribution ◽  
Biological Production ◽  
Carbon Cycle Model ◽  
Sensitivity Studies

Abstract. The carbon cycle is a major forcing component in the global climate system. Modelling studies, aiming to explain recent and past climatic changes and to project future ones, increasingly include the interaction between the physical and biogeochemical systems. Their ocean components are generally z-coordinate models that are conceptually easy to use but that employ a vertical coordinate that is alien to the real ocean structure. Here, we present first results from a newly-developed isopycnic carbon cycle model and demonstrate the viability of using an isopycnic physical component for this purpose. As expected, the model represents well the interior ocean transport of biogeochemical tracers and produces realistic tracer distributions. Difficulties in employing a purely isopycnic coordinate lie mainly in the treatment of the surface boundary layer which is often represented by a bulk mixed layer. The most significant adjustments of the ocean biogeochemistry model HAMOCC, for use with an isopycnic coordinate, were in the representation of upper ocean biological production. We present a series of sensitivity studies exploring the effect of changes in biogeochemical and physical processes on export production and nutrient distribution. Apart from giving us pointers for further model development, they highlight the importance of preformed nutrient distributions in the Southern Ocean for global nutrient distributions. The sensitivity studies show that iron limitation for biological particle production, the treatment of light penetration for biological production, and the role of diapycnal mixing result in significant changes of nutrient distributions and liniting factors of biological production.

scholarly journals Adjoint sensitivity of the air-sea CO<sub>2</sub> flux to ecosystem parameterization in a three-dimensional global ocean carbon cycle model

2007 ◽  
Vol 4 (2) ◽  
pp. 1377-1404 ◽  
Author(s):  
J. F. Tjiputra ◽  
A. M. E. Winguth
Keyword(s):  
Carbon Cycle ◽  
Marine Ecosystem ◽  
Three Dimensional ◽  
Co2 Flux ◽  
Global Ocean ◽  
Ecosystem Structure ◽  
Cycle Model ◽  
Ocean Carbon Cycle ◽  
Carbon Cycle Model ◽  
Ocean Carbon

Abstract. The regional sensitivity of air-sea CO2 flux to ecosystem components and parameters in a three-dimensional ocean carbon cycle model is estimated using an adjoint model. Adjoint sensitivities to the global air-sea CO2 flux reveal that the biological component of the model is significant in the high latitudes of both hemispheres and in the Equatorial Pacific. More detailed analysis indicates that zooplankton grazing activity plays a major role in the carbon exchange in the above regions. The herbivores' ingestion parameter in the model regulates the flux of remineralized (i.e. regenerated) biogenic nutrients; thus, substantially controls the biological production and the concentration of dissolved inorganic carbon (DIC) in the euphotic zone. Over a 10-year period, reducing the herbivores' ingestion parameter in the model by 25% could increase the global uptake of atmospheric carbon by 6 Pg C. Thus, climate induced changes in the marine ecosystem structure are of importance for the future uptake of atmospheric CO2.

scholarly journals Including an ocean carbon cycle model into <i>i</i>LOVECLIM (v1.0)

2015 ◽  
Vol 8 (5) ◽  
pp. 1563-1576 ◽  
Author(s):  
N. Bouttes ◽  
D. M. Roche ◽  
V. Mariotti ◽  
L. Bopp
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Climate Model ◽  
Dissolved Inorganic Carbon ◽  
Carbon Dioxide Concentration ◽  
Deep Ocean ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Radiative Balance ◽  
Ocean Carbon

Abstract. The atmospheric carbon dioxide concentration plays a crucial role in the radiative balance and as such has a strong influence on the evolution of climate. Because of the numerous interactions between climate and the carbon cycle, it is necessary to include a model of the carbon cycle within a climate model to understand and simulate past and future changes of the carbon cycle. In particular, natural variations of atmospheric CO2 have happened in the past, while anthropogenic carbon emissions are likely to continue in the future. To study changes of the carbon cycle and climate on timescales of a few hundred to a few thousand years, we have included a simple carbon cycle model into the iLOVECLIM Earth System Model. In this study, we describe the ocean and terrestrial biosphere carbon cycle models and their performance relative to observational data. We focus on the main carbon cycle variables including the carbon isotope ratios δ13C and the Δ14C. We show that the model results are in good agreement with modern observations both at the surface and in the deep ocean for the main variables, in particular phosphates, dissolved inorganic carbon and the carbon isotopes.

scholarly journals Optimization of Biological Production for Indian Ocean upwelling zones: Part – I: Improving Biological Parameterization via a variable Compensation Depth

2017 ◽  
Author(s):  
Mohanan Geethalekshmi Sreeush ◽  
Vinu Valsala ◽  
Sreenivas Pentakota ◽  
Koneru Venkata Siva Rama Prasad ◽  
Raghu Murtugudde
Keyword(s):  
Indian Ocean ◽  
Carbon Cycle ◽  
Global Ocean ◽  
New Production ◽  
Monsoon Period ◽  
Carbon Cycle Model ◽  
Chl A ◽  
Compensation Depth ◽  
The Indian Ocean ◽  
Ocean Carbon

Abstract. Biological modeling approach adopted by the Ocean Carbon Cycle Model Inter-comparison Project (OCMIP-II) provided amazingly simple but surprisingly accurate rendition of the annual mean carbon cycle for the global ocean. Nonetheless, OCMIP models are known to have seasonal biases which are typically attributed to their bulk parameterization of compensation depth. Utilizing the principle of minimum solar radiation for the production and its attenuation by the surface Chl-a, we have proposed a new parameterization for a spatially and temporally varying compensation depth which captures the seasonality in the production zone reasonably well. This new parameterization is shown to improve the seasonality of CO2 fluxes, surface ocean pCO2, biological export and new production in the major upwelling zones of the Indian Ocean. The seasonally varying compensation depth enriches the nutrient concentration in the upper ocean yielding more faithful biological exports which in turn leads to an accurate seasonality in carbon cycle. The export production strengthens by ~ 70 % over western Arabian sea during monsoon period and achieved a good balance between export and new production in the model. This underscores the importance of having a seasonal balance in model export and new production for a better representation of the seasonality of carbon cycle over upwelling regions The study also implies that both the biological and solubility pumps play an important role in the Indian Ocean upwelling zones.

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