Collaborative Research: Understanding the Role of Coupled Chemistry-climate Interactions in Internal Climate Variability

过去的大量研究都是为了了解气候和化学物质（如臭氧和水蒸气）之间的耦合如何影响气候对人为温室气体和臭氧消耗物质排放的反应。但是，这种耦合对于气候年际和十年尺度变化的重要性，代表了我们目前对气候系统的科学理解中的一个关键空白。该项目将通过分析现有的各种气候模式的数值实验，以及针对当前项目的新数值模拟来填补这一空白。该项目的成果将使人们更好地了解化学-气候耦合在气候系统中的作用。这项工作对我们理解气候变率和变化及其对地表的相关气候影响具有广泛的意义。该项目将为热带、中纬度和极地地区以及对流层和平流层的气候变率耦合化学-气候相互作用的重要性提供新的见解。它将提高我们对包括耦合化学-气候过程在设计和评估未来大集合气候模拟中的重要性的理解。特别是，它将提供一个基准，用于量化在气候变化模拟中化学-气候相互作用中模型间差异的重要性。这将有助于建立包括在全球气候模型中的过程的保真度，从而对公众对气候模型的信心和对气候科学的理解产生影响。关于化学-气候耦合相互作用在不确定性气候变化预估中的作用的新知识将对全球不同地区的社会和生态系统产生一系列潜在影响。该项目还将为来自大气科学领域代表性不足的群体的两名研究生提供指导。在工作的第一部分，研究人员将量化化学-气候耦合相互作用对气候变率的年-年时间尺度的影响。他们将在现有的和有针对性的数值气候模式实验中探索：1)有耦合化学和没有耦合化学的控制模拟之间气候变率的差异；2)大气动力学对各种化学物质的影响；3)化学物质变化对大气动力学的影响。本研究的第二部分将探讨随着世界从臭氧消耗物质增加的臭氧消耗时代（约1980-1995年）走向臭氧恢复（1995-未来），化学-气候耦合相互作用在气候变化中的作用。研究人员将重点关注：1)未来气候状态的可变性；2)地表气候在年代际尺度上的趋势；3)在化学-气候耦合模式的大集合模拟中对未来气候变化预测的不确定性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A great deal of past research has been directed at understanding how coupling between climate and chemical species such as ozone and water vapor influence the climate response to anthropogenic emissions of greenhouse gases and ozone-depleting substances. But the importance of such coupling for year-to-year and decadal-scale variations in climate represents a key gap in our current scientific understanding of the climate system. The project will fill this gap through analyses of both existing numerical experiments across a wide array of climate models, and from new numerical simulations explicitly for the current project. The outcomes of the project will lead to improved understanding of the role of chemistry-climate coupling in the climate system. The work has broad implications for our understanding of climate variability and change, and their related climate impacts at the surface. The project will provide new insights into the importance of coupled chemistry-climate interactions for climate variability in the tropics, midlatitudes, and polar regions, and at both troposphere and stratosphere. It will improve our understanding of the importance of including coupled chemistry-climate processes in designing and evaluating future large-ensemble climate simulations. In particular, it will provide a benchmark for quantifying the importance of model-to-model differences in chemistry-climate interactions in simulations of climate change. This would help establish the fidelity of the processes included in global climate models, and thus has implications for public confidence in climate models and understanding of climate science. The new knowledge about the role of coupled chemistry-climate interactions in uncertainty in climate change projections would have a range of potential implications for both society and ecosystems over various regions of the globe. The project will also provide mentoring for two graduate students from groups underrepresented in the atmospheric sciences. In the first part of the work, the investigators will quantify the effects of coupled chemistry-climate interactions on climate variability on year-to-year timescales. They will explore in both existing and targeted numerical climate model experiments: 1) the differences in climate variability between control simulations with and without coupled chemistry; 2) the influence of atmospheric dynamics on various chemical species; and 3) the effects of variations in chemical species on atmospheric dynamics. The second part of the work will explore the role of coupled chemistry-climate interactions in climate change as the world moves from the era of ozone depletion when ozone depleting substances increased (about 1980-1995), to ozone recovery (1995-future). The investigators will focus on 1) variability in future climate states, 2) surface climate trends on decadal timescales, and 3) uncertainty in projections of future climate changes in large-ensemble simulations of coupled chemistry-climate models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.