Atmosphere-ocean models

A number of current coupled ocean-atmosphere climate models predict that the overturning of the North Atlantic may decrease somewhat under a future warmer climate.While this is not a feature that coupled models deal with well, its direct impact on the ocean s sequestration of carbon would be to cause a significant decline in the carbon that is stored in the deep water. This is a positive feedback, as oceanic carbon uptake would decline. Flowever, the expansion of area populated by the productive cool water plankton, and the associated decline... 

Once the model was complete, it was adjusted to a steady state condition and tested using historic carbon isotope data from the atmosphere, oceans and polar ice. Several important parameters were calculated and chosen at this stage. Sensitivity analysis indicated that results dispersal of the missing carbon - were significantly influenced by the size of the vegetation carbon pool, its assimilation rate, the concentration of preindustrial atmospheric carbon used, and the CO2 fertilization factor. The model was also sensitive to several factors related to fluxes between ocean reservoirs. 

Bjorkstrom, A. 1979. A model of CO2 interaction between atmosphere,oceans, and land biota. In The Global Carbon Cycle, Bolin, B. Degens, E. T. Kempe, S. Ketner, P., Eds. SCOPE 13 J Wiley Sons New York, NY, 1979 pp 403-457. 

Simple three-box models with the atmosphere assumed to be one well-mixed reservoir and the oceans described by a surface layer and a deep-sea reservoir have been used extensively. Keeling (1973) has discussed this type of model in detail. The two-box ocean model is refined by including a second surface box, simulating an "outcropping" (deep-water forming) polar sea (e.g.. Keeling and Bolin, 1967, 1968), and to include a better resolution of the main thermo-cline (e.g., Bjorkstrom, 1979). The terrestrial biota are included in a simple manner (e.g., Bolin and Eriksson, 1959) in some studies Fig. 11-18 shows a model used by Machta (1972) where the role of biota is simulated by one reservoir connected to the atmosphere with a time lag of 20 years. 

Bjdrkstrom, A. (1979). A model of CO2 interaction between atmosphere, oceans, and land biota. In "The Global Carbon Cycle" (B. Bolin, E. T. Degens, S. Kempe, and P. Ketner, eds), pp. 403-457. Wiley, New York. 

The research published in this book uses the presently most comprehensive multicompartment model, the first which comprises a coupled atmosphere-ocean general circulation model (GCM). GCMs are the state-of-the-art tools used in climate research. The study is on the marine and total environmental distribution and fate of two chemicals, an obsolete pesticide (DDT) and an emerging contaminant (perflu-orinated compound) and contains the first description of a whole historic cycle of an anthropogenic substance, i.e. from the introduction into the environment until its fading beyond phase-out. 

Updated model versions The atmosphere and ocean models were updated to the recent model releases ECHAM5.3.02 and MPIOM-1.2.2. The update of the biogeo-chemistiy model from the beta version of HAMOCC5 used by Guglielmo (2008) to HAMOCC5.1 [Maier-Reimer et al (2005)] introduced major changes in the model. 

The comparison of model results with observations reveals significant discrepancies, especially in the Arctic, where concentrations are overestimated by the model in ocean and atmosphere. The model does not reproduce the observed latitudinal gradient of DDT in the ocean, i.e. the modelled and observed gradients have a different sign. Observations show, that the contamination of the ocean by DDT is decreasing towards the Arctic, whereas in the model simulation contaminations are increasing. 

T. C. Johns et al., The Second Hadley Center Coupled Ocean-Atmosphere GCM Model Description, Spinup, and Validation, Climate Dynamics 13 (1997) 103-34. 

Levis et al. (2003) described an algorithm based on the data of field and laboratory measurements that enables calculation of BVOC emissions being used as a component of the interactive climate model CCSM (Version 2.0) for the atmosphere-ocean-land-sea ice cover system developed by National Center for... 

Considerable progress in modeling the interactive atmosphere-ocean system has made it possible to successfully predict seasonal and interannual variability and, in particular, El Nino events. The sufficiently adequate consideration of land surface processes ensured a substantial increase in hydrological prediction reliability (river run-off included). 

All models of the C02 cycle need improvement in the way they detail the spatial distribution of soil-plant formations and in the way they specify exchange processes in the ocean and at the atmosphere-ocean boundary. Accurate parameterizations of all studied elements of the biogeochemical carbon cycle should be synthesized into a single system. Such an attempt was made in the block scheme of the model shown in Figure 3.6. The main sources of C02 are the day-to-day activity of land and marine animals, photochemical reactions, decomposition of dead organic... 

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