INSPIRE: Nonequilibrium Statistical Mechanics of Natural Climate Variability: Sea-Surface Temperature and Ocean Heat Content

INSPIRE奖的部分资金来自地球科学理事会海洋科学部的物理海洋学项目、物理学部的数学物理项目、数学科学部的计算数学项目和材料研究部的凝聚态物质与材料理论项目，这些项目都隶属于数学与物理科学理事会。知识价值：气候系统的自然变率主要是通过观测、气候模拟和分析来理解的。自然气候变率表现为大尺度、连贯的模式，如厄尔尼诺和北大西洋涛动。目前还没有基本理论来解释或预测气候系统的自然变率。气候系统是由太阳辐射的能量驱动的，太阳辐射以长波辐射的形式释放回太空。除人为强迫外，气候系统大致处于热力学非平衡的稳定状态。物理界最近的进展使人们对非平衡稳态的自然变异性有了新的更深入的认识。非平衡稳态具有能量途径，将其自然变异性引导到定义良好的生命周期中。这些生命周期表现为气候系统中可见的自然变率模式。这个INSPIRE项目将在物理学家和气候科学家之间建立一种新的跨学科合作，发展和应用非平衡波动理论来理解和预测气候变化。该项目利用了这两个社区之间的技术联系。线性高斯模型（LGMs）是显示非平衡稳态波动的最简单模型之一。物理和气候学界已经独立地对lgm进行了广泛的研究，并证明了对某些气候现象的预测能力。lgm允许将非平衡物理的结果直接应用于气候现象，并为非平衡物理的新发展提供了一个焦点。INSPIRE项目将开发一种理解气候自然变率的新方法，并将气候系统引入统计物理学的一个新应用领域。非平衡稳态的背景为理解自然变率的模式提供了一个新的理论框架。新的诊断，基于模式的相空间动力学，将开发和应用于模型和数据的层次结构。对具有不同恒定二氧化碳浓度的模式和具有人为强迫的模式的研究，将有助于深入了解在气候变化下海洋表面温度和海洋热含量的自然变率将如何演变，以及这些过程在现有气候模式中如何得到很好的体现。非平衡物理学的新理论工作将在气候变率驱动的方向上扩展目前的理论。该项目有两个主线：1)将非平衡理论应用于海表面温度和上层海洋热含量数据集的层次；2)理论工作，以推动非平衡物理对气候系统的重要方向。更广泛的影响：拟议的工作将作为统计物理学应用于其他自然气候变化模式的模板。线性高斯模型的自然变异性可以为整个自然气候变异性谱提供零假设，即使在它失败的情况下也会提供洞察力。该项目将促进物理学和气候学界的交叉发展，并为研究提供新的方向。最后，该项目将在气候建模、统计物理和气候数据分析方面交叉培养一名研究生和一名博士后研究员，并将支持一名年轻教员的智力成长。

This INSPIRE award is partially funded by the Physical Oceanography Program in the Division of Ocean Sciences in the Directorate for Geosciences, and the Mathematical Physics program in the Division of Physics, the Computational Mathematics Program in the Division of Mathematical Sciences and the Condensed Matter and Materials Theory Program in the Division of Materials Research, all in the Directorate for Mathematical and Physical Sciences.Intellectual Merit: The natural variability of the climate system is primarily understood through observations, climate modeling, and analysis. Natural climate variability takes the form of large-scale, coherent patterns such as El-Nino and the North Atlantic Oscillation. There is currently no fundamental theory to explain or predict the natural variability of the climate system. The climate system is driven by energy from incoming solar radiation, which is then released back to space as outgoing long-wave radiation. The climate system, apart from anthropogenic forcing, is approximately in a thermodynamically non-equilibrium steady-state. Recent progress within the physics community has led to a new and deeper understanding of natural variability in non-equilibrium steady-states. Non-equilibrium steady-states have energetic pathways that channel their natural variability into well-define lifecycles. These lifecycles are manifested as the patterns of natural variability seen in the climate system. This INSPIRE project will create a new interdisciplinary collaboration between physicists and climate scientists developing and applying theories of non-equilibrium fluctuations to the problem of understanding and predicting climate variability. This project leverages a technical linkage between these two communities. Linear Gaussian Models (LGMs) are among the simplest models that display non-equilibrium steady-state fluctuations. LGMs have independently been extensively studied by both the physics and climate communities, and have demonstrated predictive skill for some climate phenomena. LGMs allow the immediate application of results from non-equilibrium physics to climate phenomena, and provide a focus for new developments in non-equilibrium physics.This INSPIRE project will develop a new approach to understanding the natural variability of climate and introduce the climate system as a new application area for statistical physics. The context of non-equilibrium steady-states provides a new theoretical framework for understanding the patterns of natural variability. New diagnostics, based on the phase-space dynamics of the patterns, will be developed and applied to a hierarchy of models and data. Study of models with different constant carbon dioxide concentrations, and models with anthropogenic forcing will provide insight into how the natural variability of Sea Surface Temperature and ocean heat content will evolve under climate change and how well-represented these processes are in present climate models. New theoretical work in non-equilibrium physics will extend current theory in directions motivated by climate variability. The project has two threads: 1) the application of non-equilibrium theory to a hierarchy of sea surface temperature and upper ocean heat content datasets; and 2) theoretical work to advance non-equilibrium physics in directions that are important for the climate system.Broader Impacts: The proposed work will serve as a template for application of statistical physics to other patterns of natural climate variability. The natural variability of Linear Gaussian Models can provide a null hypothesis for the entire spectrum of natural climate variability, and will provide insight even in situations where it fails. The project will serve to cross-fertilize the physics and climate communities and provide new directions for research. Finally, the project will cross-train one graduate student and one post-doctoral researcher in climate modeling, statistical physics, and climate data analysis, and will support the intellectual growth of a young faculty member.