Biogeochemical models carbon cycle

Since Phaeocystis plays a key role in element fluxes relevant to climate the results presented here have implications for biogeochemical models of cycling of carbon and sulphur. Sea-to-air exchange of C02 and dimethyl sulphide (DMS) has been calculated on the basis of measurements during single-year cruises. The considerable annual variation in phytoplankton and in its Phaeocystis component reported here does not warrant extrapolation of such figures. 

An important example of non-linearity in a biogeochemical cycle is the exchange of carbon dioxide between the ocean surface water and the atmosphere and between the atmosphere and the terrestrial system. To illustrate some effects of these non-linearities, let us consider the simplified model of the carbon cycle shown in Fig. 4-12. Ms represents the sum of all forms of dissolved carbon (CO2, H2CO3, HCOi" and... 

Fig. 4-12 Simplified model of the biogeochemical carbon cycle. (Adapted from Rodhe and Bjdrkstrdm (1979) with the permission of the Swedish Geophysical Society.)...

Wigley, T. M. L. (1991). A simple inverse carbon cycle model. Global Biogeochem. Cycles 5,373-382. 

Guilderson, T.P., K. Caldeira, and P.B. Duffy. 2000. Radiocarbon as a diagnostic tracer in ocean and carbon cycle modeling. Global Biogeochemical Cycles 14(3) 887-902. 

CONCEPTUAL SCHEME FOR A MODEL OF THE GLOBAL BIOGEOCHEMICAL CARBON CYCLE... 

Conceptual scheme for a model of the global biogeochemical carbon cycle 161... 

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... 

Tarko A.M. (2003). Analysis of Global and Regional Changes in Biogeochemical Carbon Cycle A Spatially Distributed Model, Interim Report IR-03-041. IIASA, Laxenburg, Austria, 28... 

Toggweiler J. R., Gnanadesikan A., Carson S., Mumane R., and Sarmiento J. L. (2003) Representation of the carbon cycle in box models and GCMs 1. Solubility pump. Global Biogeochem. Cycles 1026, doi 10.1029/2001GB001401. 

Iglesias-Rodriguez D. M., Brown C. W., Doney S. C., Kleypas J. A., Kolber D., Kolber Z., Hayes P. K., and Ealkowski G. P. (2002) Representing key phytoplankton functional groups in ocean carbon cycle models coccolithophorids. Global Biogeochem. Cycles 16 (in press). 

DeFries R. S., Field C. B., Fung L, Collatz G. J., and Bounoua L. (1999) Combining satellite data and biogeochemical models to estimate global effects of human-induced land cover change on carbon emissions and primary productivity. Global Biogeochem. Cycles 13, 803-815. 

Stephens B. B., Keeling R. F., Heimann M., Six K. D., Mumane R., and Caldeira K. (1998) Testing global ocean carbon cycle models using measurements of atmospheric O2 and CO2 concentration. Global Biogeochem. Cycles 12, 213-230. 

Here 50, denotes the observed deviation of the atmospheric O, concentration from a standard. The atmospheric tracer APO is dominated primarily by oceanic gas exchanges in addition to a relatively small contribution from fossil fuel not accounted for by the terrestrial stoichiometric factor (i.e., the fossil fuel component scaled by the factor Observations of the seasonal variation of APO in conjuction with surface-water oxy gen measurements have been used to constrain the large-scale magnitude of the air-sea gas exchange coefficient (Keeling et al, 1998) and of marine productivity (Six and Maier-Reimer, 1996 Balkan.ski et al, 1999). Mean annual gradients of APO have also been shown to provide powerful constraints on biogeochemical air-sea fluxes computed by ocean-circulation models with an embedded ocean carbon cycle (Stephens et al, 1998). 

Figure 3 Results from a simple three-box ocean carbon cycle model, (a) The physical circulation and modeled radiocarbon (A C) values, (b) The model biogeochemical fields, ocean DIG, and phosphate PO4) and atmospheric pCOa. From Toggweiler JR and Sarmiento JL, Glacial to inter-glacial changes in atmospheric carbon dioxide The critical role of ocean surface waters in high latitudes, The Carbon Cycle and Atmospheric CO2. Natural Variations Archean to Present, Sundquist ET and Broecker WS (eds.), pp. 163-184, 1985, Copyright [1985]. American Geophysical Union. Adapted by permission of American Geophysical Union.

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