Global Atmospheric Chemistry: Uncertainties and Errors; Modes and Parametric Models

将继续研究化学-输运模型（CTMs）的基本特性，重点是：(1)校正由于网格分辨率导致的CTMs数值误差；(2)化学模式研究，包括推导平流层-对流层耦合化学模式和建立与CTM具有相同模式的简化（参数）模型。一种计算与网格分辨率相关的数值误差的新方法将被开发和测试。结果将广泛适用于所有CTMs，不仅可以表征分辨率误差，还可以用来帮助纠正它们。CTMs中全局化学模态的存在将被用作模型的基本诊断。描述甲烷年代际扰动的对流层化学模式将首次在CTM中与涉及氧化亚氮和臭氧的长达一个世纪的平流层模式耦合。全局化学模式将用于开发使用CTM灵敏度计算的降维参数模型。将计算一个降维雅可比矩阵，它完全定义了参数模型，并可与完整CTM的模态进行比较。更广泛的影响范围从改善地球系统模式中的大气化学/组成元素到提供关于全球变化的更准确的科学输入。在预估大气成分时，即使对不确定性的一个分量进行量化，也应该有利于地球系统模式及其政策应用。该项目还将帮助从事大气化学研究的本科生、博士生和博士后具备诊断和分析复杂地球系统模型所需的数学技能。

Research will be continued on the basic properties of chemistry-transport models (CTMs), focusing on: (1) correction of the numerical error in CTMs due to grid resolution, and (2) chemical mode studies that include the derivation of a stratosphere-troposphere coupled chemistry mode and the formulation of a simplified (parametric) model having the same modes as the CTM. A new approach for calculating the numerical errors associated with grid resolution will be developed and tested. The results will be broadly applicable to all CTMs, and will not only characterize the resolution errors but may also be used to help correct them. The existence of global chemical modes in CTMs will be used as a fundamental diagnostic of the models. The tropospheric chemical mode that describes decadal perturbations to methane will be coupled, for the first time in a CTM, with the century-long stratospheric mode involving nitrous oxide and ozone. Global chemical modes will be used to develop reduced-dimension parametric models using sensitivity calculations with a CTM. A reduced-dimension Jacobian will be calculated that completely defines the parametric model and can be compared with the modes of the full CTM.Broader impacts range from improving the atmospheric chemistry/composition elements in Earth system models to providing more accurate scientific input on global change. The quantification of even one component of uncertainty in projecting atmospheric composition should benefit Earth system models and their policy applications. This project will also help prepare undergraduate students, doctoral students, and post-docs working in atmospheric chemistry with the mathematical skills needed to diagnose and analyze complex Earth system models.