Understanding the Dynamic Land-Atmosphere System: Multiple Equilibrium States and Climate Variability

一些模拟研究表明，陆地生物圈-大气相互作用可能导致地球气候系统存在多重平衡。然而，诊断全球气候系统模式中是否存在多种平衡状态，以及它们为什么存在于它们存在的地方，是极具挑战性的；多重平衡对区域-全球气候的长期变率和变化的影响尚不清楚。该项目的研究目标有两个方面：第一，了解某些气候模式和某些地区多重生物圈-大气平衡存在的机制；第二，了解具有多种平衡状态的区域气候系统的自然变率。知识价值。基于植被-降水相互作用的概念动力学模型，PI提出了四个假设。这些假设将使用由美国国家大气研究中心开发的全球环流模式和通过改变模式内某些特性的量化或改变某些过程的参数化而衍生的模式来评估。这项工作的完成将为以下方面提供新的见解：1 .全球大气环流模式模拟的全球生物圈-大气系统存在多种平衡状态；提高对气候变率、气候变化及其模式依赖性的认识。更广泛的影响。该研究将更好地理解具有多个平衡的系统的行为，这可能会增加受影响人群适应和减轻不同平衡之间潜在气候变化的影响的能力。本项目为气候系统模拟和气候-植被相互作用领域的本科生和研究生提供学习经验和培训。

Several modeling studies indicate that terrestrial biosphere-atmosphere interactions may give rise to the existence of multiple equilibria in the Earth's climate system. However, diagnosing whether multiple equilibrium states exist in global climate system models and why they exist where they do is extremely challenging; the impact of multiple equilibria on the long-term variability and changes of regional-global climates is not well understood. The research objectives of this project are to two-fold: first, to understand the mechanisms responsible for the existence of multiple biosphere-atmosphere equilibria in certain climate models and over certain regions; second, to understand the natural variability of regional climate systems that do possess multiple equilibrium states.Intellectual merit. Based on a conceptual dynamical model for vegetation-precipitation interactions, the PI develops four hypotheses. These hypotheses will be evaluated using a global circulation model developed by the National Center for Atmospheric Research and models that will be derived from it by changing the quantification of certain properties or changing the parameterization of certain processes within the model. Completion of this work will offer new insights into:1. The existence of multiple equilibrium states in the global biosphere-atmosphere system as simulated by global general circulation models, and 2. An improved understanding of climate variability, climate changes, and their model dependence.Broader impacts. The research will provide a better understanding about how a system with multiple equilibria behaves, which may increase the ability of affected populations to adapt to and mitigate the impact of potential climate transitions between different equilibria. This project provides learning experiences and training for undergraduate and graduate-level students in the field of climate system modeling and climate-vegetation interactions.