Interactive Canopies for a Climate Model

Abstract

Abstract Climate models depend on evapotranspiration from models of plant stomatal resistance and leaf cover, and hence they depend on a description of the response of leaf cover to temperature and soil moisture. Such a description is derived as an addition to the Biosphere–Atmosphere Transfer Scheme and tested by simulations in a climate model. Rules for carbon uptake, allocation between leaves, fine roots, and wood, and loss terms from respiration, leaf, and root turnover and cold and drought stress, are used to infer the seasonal growth of leaf area as needed in a climate model, and to provide carbon fluxes (assuming also a simple soil carbon model) and net primary productivity. The scheme is tested in an 11-yr integration with the NCAR CCM3 climate model. After a spinup period of several years, the model equilibrates to a seasonal cycle plus some interannual variability. Effects of the latter are noticeable for the Amazon. Overall, drought stress has nearly as large an effect on leaf mortality as cold...