ATMOSPHERIC CARBON DIOXIDE AND RADIOCARBON: II 



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I 



Fig. 4 (a) The Suess effect in 1954 relative to preindustrial times as predicted by 

 various reservoir models, all with T am = 5 years, (b) Predicted increase in inactive 

 atmospheric C0 2 from 1700 to 1954 for the same models. Seven cases are shown, as 

 follows: 



*Ratio of the preindustrial mass of inactive carbon in the surface ocean layer to 

 that in the atmosphere. 



tExponential function of Bolin and Eriksson 3 with 7 = 0.000496 N ao , 

 r = 0.029 year" 1 . 



$ Varies from 8.9 to 9.2. 



EMPIRICAL ADJUSTMENT OF THE MODEL 



We now consider in some detail the consequences of attempting to adjust 

 parameters until the model predictions agree as closely as possible with the 

 principal observations: the observed C0 2 increase in the atmosphere, the decrease 

 in atmospheric l C/C ratio deduced from recent measurements of dated wood, 

 and the observed l C/C ratios of surface and deep-ocean water. Because the 

 experimental data are uncertain, we must consider several possible combinations 

 of parameters. 



As a preliminary step, we vary over a wide range two parameters that 

 significantly affect both the predicted inactive C0 2 increase and the Suess 

 effect. These parameters are the deep-ocean to surface-layer transfer time, T^ m , 

 and the ocean surface-layer volume. The latter is expressed in terms of the ocean 

 surface layer to atmosphere carbon ratio, N m0 /N a o. As a second step we 

 mutually adjust the atmosphere to ocean transfer time, T am , the ratio N m0 /N a o 

 again, and the biota growth factor, j3, in a search for reasonable predictions of 

 the Suess effect and atmospheric C0 2 increase. The model is now also forced to 

 predict correctly the observed l C ratio of ocean surface water. As a final step 

 we vary several parameters, one by one or in groups, to test the sensitivity of the 

 model predictions to uncertainty in the observational data. Toward the end of 



