生态系统的天气环境模拟模型

Simulators of weather environment of ecosystems.

无论对于自然的还是人为管理的生态系统,天气都是最重要的一种环境条件。用系统分析方法对生态系统进行的研究使天气模拟越来越成为非常必要的了。本文首先介绍了一个美国天气模拟模型(WGEN)的数学原理。它用马尔柯夫链和Γ-分布组成降水量子模型,产生逐日降水量。用弱平稳过程和调和分析为工具建立另一个子模型,产生逐日最高温度、最低温度和太阳辐射量。通过常规的统计学方法或灰靶白化方法可以估计模型参数。于是,就可由WGEN生出Alabama州天气模型ALWGEN和北京天气模型BJWGEN。考虑到篇幅有限,本文没有具体介绍上述估计方法,也只是扼要介绍了用Monte Carlo Bootstrap方法进行模型校验和验证的问题。最后,简单地讨论了天气模拟模型的应用。如IPM研究中的风险分析,生态系统管理决策,农业生态区域规划等课题,对天气模型都有现实的或潜在的需要。

Weather is of paramount importance among environmental elements for both natural and managed ecosystems. System analysis makes it increasingly imperative to simulate weather in research projects related to ecosystems. In this paper, a summary firstly introduces mathematical principles of an American weather generator (WGEN), which is constructed with Markov chain——gamma distribution as a model to produce daily precipitation data and weakly stationary process——harmonic analysis as tools to build another model generating daily maximum temperature, minimum temperature and solar radiation for a given location. Then,WGEN derives ALWGEN and BJWGEN for Alabama and Beijing, respectively, after the model parameters are estimated by procedures of conventional statistics or the grey target bleaching. Taking the paper size into account, however,the concrete procedures are not demonstrated here; and also, the model verification and validation by Monte Carlo bootstraping are mentioned only without detailed description.Finally,a brief discussion on applications of the weather simulators is made. Risk analysis in IPM programs,decision making in ecosystems management, ecologically planning of agricultural areas, are all need weather simulators really for the present or potentially for the future.