An Exploratory Study for Coupling Biota, Energy and the Hydrological Cycle in Simple Nonlinear Models of Planetary Climate

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

9903125 Gupta This is an exploratory, interdisciplinary proposal to develop a new class of nonlinear 0-D models, called Dynamic Area Fraction Models (DAFMs). They are designed to investigate the 'physiology' of an Earth-like system in which the biota, the hydrological and carbon cycles, the oceans and ice caps, and the radiative energy balance are nonlinearly coupled. A well-known model on this context is the Daisyworld model of Watson and Lovelock (1983). Recently, it has been shown (Weber, J. Climate, 2000) that the method of parameterization of the heat transport in Daisyworld maintains equilibrium local temperatures independent of solar radiation when both species of daisy are present. Other serious criticisms of the Daisyworld come form the fact that it does not include the major components of an earth-like climate: 1. It has no water cycle with evaporation, precipitation, and atmospheric circulation; 2. It has no oceans; 3. It has no ice caps, and 4. It contains no carbon cycle. DAFMs are designed specifically to couple dynamic changes in surface characteristics to radiative and mass balances in a realistic way. This objective is accomplished by treating the relative size of regions in a box model as prognostic fields that update dynamically with functions of the local balances. Diagnostic studies will be carried out to compare the effect of different parameterizations on the homeostasis of planetary temperature under a warming sun between the Daisyworld and the DAFMs. Simple nonlinear mathematical models are versatile and ideal for identifying key parameters and feedbacks, and discrepancies between model predictions and observations, which is not so easy to do in complex climate models such as GCMs. This study would serve as a basis to submit a three-year comprehensive, interdisciplinary research proposal to NSF.