Cycle Model

During a forum convened by the World Wildlife Fund and the Conservation Foundation in May 1990, various steering committees recommended that a three-part life-cycle model be adopted. This model consists of the following ... 

The most common way in which the global carbon budget is calculated and analyzed is through simple diagrammatical or mathematical models. Diagrammatical models usually indicate sizes of reservoirs and fluxes (Figure 1). Most mathematical models use computers to simulate carbon flux between terrestrial ecosystems and the atmosphere, and between oceans and the atmosphere. Existing carbon cycle models are simple, in part, because few parameters can be estimated reliably. 

Budgets and cycles can be considered on very different spatial scales. In this book we concentrate on global, hemispheric and regional scales. The choice of a suitable scale (i.e. the size of the reservoirs), is determined by the goals of the analysis as well as by the homogeneity of the spatial distribution. For example, in carbon cycle models it is reasonable to consider the atmosphere as one reservoir (the concentration of CO2 in the atmosphere is fairly uniform). On the other hand, oceanic carbon content and carbon exchange processes exhibit large spatial variations and it is reasonable to separate the... 

The advent of fast computers and the availability of detailed data on the occurrence of certain chemical species have made it possible to construct meaningful cycle models with a much smaller and faster spatial and temporal resolution. These spatial and time scales correspond to those in weather forecast models, i.e. down to 100 km and 1 h. Transport processes (e.g., for CO2 and sulfur compounds) in the oceans and atmosphere can be explicitly described in such models. These are often referred to as "tracer transport models." This type of model will also be discussed briefly in this chapter. 

Fig. 11-9 (a) The vertical distributions of alkalinity (Aik) and dissolved inorganic carbon (DIC) in the world oceans. Ocean regions shown are the North Atlantic (NA), South Atlantic (SA), Antarctic (AA), South Indian (SI), North Indian (NI), South Pacific (SP), and North Pacific (NP) oceans. (Modified with permission from T. Takahashi et ah, The alkalinity and total carbon dioxide concentration in the world oceans, in B. Bolin (1981). Carbon Cycle Modelling," pp. 276-277, John Wiley, Chichester.)... 

Bacastow, R. B. and Bjdrkstrom, A. (1981). Comparison of ocean models for the carbon cycle. In "Carbon Cycle Modeling" (B. Bolin, ed.), pp. 29-79. Wiley, New York. 

Bolin, B. (ed.) (1981). "Carbon Cycle Modeling." Wiley, New York. 

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

Hudson RJM, Gherini SA, Watras CJ, Porcella DB. 1994. Modeling the biogeochemical cycle of mercury in lakes the Mercury Cycling Model (MCM) and its application to the MTL study lakes. In Watras CJ, Huckabee JW, editors. Mercury pollution integration and synthesis. Boca Raton (FL) Lewis Publishers, CRC Press Inc., p. 473-523. 

Tajika, E. (1998) Climate change during the last 150 million years reconstruction from a carbon cycle model. Earth Planet. Sci. Lett., 160, 695-707. 

Kashiwagi, H., Shikazono, N. and Tajika, E. (2000) Global carbon cycle model in the Cenozoic. 10th Annual V.M. Goldschmidt Conference, September 3-8, Oxford University Abst. 

A. W. King, W. R. Emanuel, and W. M. Post, Projecting future concentrations of atmospheric COi with global carbon cycle models the importance of simulating historical changes. Environmental Management /6 91 (1992). 

I recommend that you follow a more traditional systems development life-cycle model (SDLC) when developing a comprehensive SAS macro-based reporting system. Unlike much of the one-time-only SAS programming that occurs for a clinical trial, you need to ensure that a general-purpose SAS macro system is robust enough to handle any problem it encounters. The systems development life-cycle approach to software development will help you to build strong software applications with SAS. 

At this point it is important to note that the flow model (a hydrologic cycle model) can be absent from the overall model. In this case the user has to input to the solute module [i.e., equation (1)] the temporal (t) and spatial (x,y,z) resolution of both the flow (i.e., soil moisture) velocity (v) and the soil moisture content (0) of the soil matrix. This approach is employed by Enfield et al. (12) and other researchers. If the flow (moisture) module is not absent from the model formulation (e.g., 14). then the users are concerned with input parameters, that may be frequently difficult to obtain. The approach to be undertaken depends on site specificity and available monitoring data. 

Mackay D, Yeun ATK (1983) Mass transfer coefficients correlations for volatilisation of organic solutes from water. Environ Sci Technol 17 211-233 Maier-Reimer E, Kriest I, Segschneider J, Wetzel P (2005) The UAMburg Ocean Carbon Cycle Model HAMOCC5.1 - Technical Description Release 1.1 -. MPI Reports on Earth System Science No. 14 1-57... 

Siegenthaler, V., and K. O. Miinnich. 1981. 13C/12C fractionation during C02 transfer from air to sea. In Carbon Cycle Modelling. Ed. B. Bolin, New York John Wiley and Sons, pp. 249-57. 

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