Energy Balance Model

( i ). What sensitivity does the standard model exhibit to changes in A, B, C, all the albedos, T_CRIT and the fractional cloud amount?

( ii ). Can you find more than one way of modifying the model that produces the top-of-the-atmosphere fluxes prescribed (i.e. both the longwave out and the absorbed solar)? Check with your classmates - they may have a different solution (s) - can yours and theirs both be correct? In particular what do your experiments suggest about the opportunities for "validating" climate model results from restricted observations such as these satellite data?

( iii ). Return to the basic model and impose a different observed cloud distribution . You could try the observed mean cloud amounts for 1979 given in Table B.2 in the text. How do these values change (a) surface climate; (b) satellite-observed fluxes from the control climate shown in Table B1 of the text? Can you modify climate features (as described above) to regain the original satellite fluxes?

( iv ). Suppose CO₂ increases caused a decrease in cloud amount by the between 10 and 20 percent. How is the climate affected? Could satellite measurements of zonal fluxes be a way of detecting such climate changes?

( v ). The traditional EBM simulations were examinations of the sensitivity of the model to changes in the solar constant. This will give you a 'feel' for the basic characteristics of the model and how it responds to a simple perturbation. Find the percentage change in solar constant to initiate a complete glaciation of the Earth.

Other questions which will be prompted by these exercises and the associated references are:

( vi ) If Sellers' (1969) rather Budyko's (1969) formulation had been used for the transport term in the Equation [ Transport = C (T - T) ], how would the results of the model change?

( vii ). How might the long timescale effects of the ocean be included in EBMs?

( viii ). How does the 'atmospheric circulation' encapsulated in an EBM compare with that simulated by a GCM?

Budyko, M.I., 1969, The effect of solar radiation on the climate of the earth, Tellus, 21, 611-619.

North, G.R., Cahalan, R.F. and Coakley, J.A., 1981, Energy balance climate models, Rev. Geophys. Space Phys., 19, 91-121.

Warren, S.G. and Schneider, S.H., 1979, Seasonal simulation as a test for uncertainties in the parameterization of a Budyko-Sellers zonal climate model, J. Atmos. Sci., 36, 1377-1391

Last updated on 10/13/09 02:22 PM by Zong-Liang Yang