Revision as of 11:32, 28 September 2014

Daisy World介绍

1970年代初期，英国科学家James Lovelock提出了盖娅假说（Gaia Hypothesis）。Lovelock认为地球气候系统是一个高度耦合的系统，生物圈和非生物圈之间有很强的动态反馈过程。在有限范围的外强迫条件下，地球系统可以通过交互作用，产生适宜生命生存的动态气候平衡。

为示范他的假说，1983年Lovelock与Andrew Watson合作发展了一个简单的数值模型[Watson and Lovelock (1983) “Daisyworld”]。 In defending his hypothesis in the scientific community, Lovelock developed in collaboration with Andrew Watson a simple numerical model as an elegant metaphor for a self-regulating planetary system -- see Watson and Lovelock (1983). Termed "Daisy World", this model has received much analysis and been widely discussed in the scientific community. The Daisy World model illustrates one possible mechanism through which the biota might optimize its abiotic environment (simplified to be global temperature) by means by means of negative feedback. It is an heuristic model, that is, one that describes a mechanism by which such optimization might occur. After publication by Watson and Lovelock, Daisy World took on a life of its own, one independent of its relationship to the Gaia Hypothesis, as an example of a self-regulating system.

The set of coupled equations describing Daisy World can easily be solved via a realization of the model in STELLA. When exploring Daisy World with such a model, it quickly becomes apparent that even this very simple system exhibits a rich variety of complex and sometimes surprising behaviors.

基本模式

Watson and Lovelock (1983) Daisyworld 基本模式

基本实验

不同死亡率 不同覆盖率（海洋面积）

作业要求

• 同学需自行编写基本Daisyworld模型，但使用的程序语言不限。可使用Fortran, C, C++, Python, Mathematica, Matlab, IDL等。
• 网上有许多Daisyworld程序，同学可以参考，但不可抄袭。

学期报告延伸建议

除了编写基本的Daisyworld模型及完成基本实验以外，同学们可以探索以下任一种或多种延伸变化，作为学期报告主题，也可以自己提出其他变化。

• 假设daisies可以在不同纬度分布，且不同纬度因太阳入射角不同，daisy反照率对行星整体反照率的影响不同。
• 假设daisies种类更多（生物多样性更高），对系统稳定度的影响
• Daisy-Rabbit-Fox World

参考资料

• James Lovelock's Website
• The Gaia Hypothesis