32. Climate system models — a brief introduction

Abstract

Publisher Summary Models are, generally speaking, descriptions of nature. There are several possibilities to describe nature. There is the artist's point of view—there are narrative models, and there are physical and mathematical models. In this chapter, only mathematical models of the climate system are discussed. Mathematical models are a set of differential and diagnostic equations. These equations describe the dynamics of components of the climate system with varying degree of approximation. Most equations can be derived from the fundamental laws of conservation of energy, momentum, and mass, and such a set of equations is referred to as “deductive model.” Climate models are generally quasi-deductive, because they include some empirical parameterization of processes that cannot be deduced from fundamental laws, such as the subgrid-scale motion. In parameterization, only the effect of a process on the system is mathematically described. In contrast to deductive models, inductive models are not derived from first principles. Instead, the dynamics of climate processes are formulated in mathematical terms without explicit consideration of fundamental physical constraints. Inductive models are used to demonstrate the plausibility of climate processes and to explore the consequences of assumptions imposed on the system.