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close this bookForests, Climate, and Hydrology: Regional Impacts (UNU, 1988, 217 pages)
close this folder8. Review of general circulation models as a basis for predicting the effects of vegetation change on climate
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View the documentIntroduction
View the documentGeneral circulation models
View the documentResponse to variation in land surface properties
View the documentGCM Simulations of tropical rainfall
View the documentRecommendations for future research
View the documentSymbols and abbreviations
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This paper reviews the atmospheric general circulation model as a tool for study of the climatic response to changes in vegetation in the tropics. It concentrates on (a) the models' treatments of land surface processes, which are crucial to estimations of the climatic response to variations in vegetation, and (b) the sensitivities of the models as revealed by experiments with perturbations of these properties, mainly the surface solar albedo and moisture availability. The quality of the model simulations in the tropics is briefly reviewed, with the emphasis on rainfall over continents, for which a good simulation is most important in sensitivity experiments.

It should be noted that for studies of global climatic change it is not appropriate to assume that sea surface temperatures are unaffected. However, because of the general inferiority to date of simulations of the atmosphere with coupled ocean-atmosphere models, such perturbation experiments have been made mostly with prescribed sea surface temperatures. The review of GCM parametrizations of land surface processes is necessarily brief compared with that of Carson (1982). Similarly, reference to Dickinson (1980) is recommended for a specific discussion of the likely effects of tropical deforestation on climate.