Natural Modes and Time Scales in Atmospheric Chemistry

大气化学中的自然模式和时间尺度

• 批准号: 9632633
• 负责人: Michael Prather
• 金额: $ 30.75万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9632633&HistoricalAwards=false
• 关键词: Natural; Modes; Time; Scales; Atmospheric

9632633 Prather This project addresses natural modes in atmospheric chemistry, defined as patterns in the concentrations of atmospheric chemical species. The pattern can include co-variation of coupled chemicals (e.g., methane, carbon monoxide, and hydroxyl radical), the vertical and/or latitudinal gradients in trace gases (e.g., nitrous oxide, ozone), or even the seasonal cycle of a trace gas at a location. Prior work has show that natural modes are a mathematically rigorous, fundamental property of the chemical transport system and do not depend on the manner of forcing; a unique mixture of modes is excited by perturbations to a single species; true time scales in atmospheric chemistry are often different from the steady-state lifetimes; and the steady-state lifetime and pattern can be derived from the natural modes. Therefore, identification of the natural modes in current atmospheric chemical transport models is useful for diagnostics, but also for prediction. In particular, models used for understanding the impact of anthropogenic emissions of trace gases such as methane, methyl bromide, or nitrous oxide on global ozone distribution have reached a large degree of complexity. Natural mode analysis could help in analyzing model results and explain effects such delayed recovery of ozone depletion after stopping emissions of a short-lived gas like methyl bromide. In the course of this project, this analysis technique will be further developed and extended to more complex 1-dimensional, as well as 2- and 3-dimensional systems. ***

9632633更确切地说，这个项目涉及大气化学中的自然模式，其定义为大气化学物质浓度的模式。这种模式可以包括耦合化学物质(例如甲烷、一氧化碳和羟基自由基)的协变、痕量气体(例如一氧化二氮、臭氧)的垂直和/或纬度梯度，甚至是某一地点的痕量气体的季节周期。以前的工作表明，自然模式是化学传输系统的一种严格的数学基本性质，不依赖于强迫的方式；模式的独特混合物是由对单一物种的扰动所激发的；大气化学中的真实时间尺度往往不同于稳态寿命；稳态寿命和模式可以从自然模式中得到。因此，识别当前大气化学输送模式中的自然模式不仅对诊断有用，而且对预测也有帮助。特别是，用于理解甲烷、甲基溴或一氧化二氮等微量气体的人为排放对全球臭氧分布的影响的模型已经达到很大程度的复杂性。自然模式分析可以帮助分析模型结果，并解释停止甲基溴等短期气体排放后臭氧消耗恢复延迟等影响。在这个项目的过程中，这一分析技术将进一步发展和推广到更复杂的一维以及二维和三维系统。***