Middle Atmosphere Processes and Lifetime Evaluation for ODSs and GHGs (MAPLE)

ODS 和 GHG 的中层大气过程和寿命评估 (MAPLE)

• 批准号: NE/J008621/1
• 负责人: Martyn Chipperfield
• 金额: $ 45.58万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ008621%2F1
• 关键词: Middle; Atmosphere; Processes; Lifetime; Evaluation

Gases emitted into the atmosphere can persist for many years or even centuries. The rate at which a gas is removed is determined by its so-called lifetime. Therefore, to understand the impact of, for example, pollutant gases emitted by human activity, it is essential to have an accurate knowledge of their atmospheric lifetimes. However, there is currently large uncertainty in the known lifetime of many key pollutant gases.Ozone-depleting substances (ODS), such as chlorofluorocarbons (CFCs), are long-lived source gases which decompose in the stratosphere to release chlorine and bromine. Under the Montreal Protocol the emissions of these species have been phased out and the ozone layer is expected to recover over the next 50-100 years. However, the rate of this recovery will depend on the atmospheric lifetime of the these gases and their replacements which are still being emitted. In fact, there is currently significant uncertainty in these atmospheric lifetimes, which are used in all model predictions of future halogen loadings (via predicted surface mixing ratio model boundary conditions). For example, a major chlorofluorocarbon CFC-11 has a quoted atmospheric lifetime of 45 years in WMO and IPCC assessments, although other studies suggest a lifetime of up to 60 years.This key uncertainty has been recognised by the recent establishment of a World Climate Research Program (WCRP) Stratospheric Processes and their Role in Climate (SPARC) project to re-evaluate the lifetimes of these ODS and their replacements (such as hydrofluorocarbons, HFCs) using up-to-date laboratory data in state-of-the-art 3-D chemistry-climate models (CCMs). These species are also efficient greenhouse gases (GHGs) and changes to their known atmospheric lifetime will change estimates of how they will affect climate change (as measured by their global warming/temperature potential (GWP/GTP)). This project will ensure full participation of the UK's chemistry-climate model (UKCA) in the WCRP/SPARC re-evaluation.Lifetime estimates directly affect model predictions of future ozone recovery. Previous CCM studies of the recovery of the ozone layer have used projected future surface ODS concentrations based on old lifetime estimates and a simple box model. Therefore, the major driver of future ozone change, the stratospheric chlorine and bromine loading, has been constrained with crude time-dependent boundary conditions. A more realistic representation of the rate of ozone recovery can be obtained by removing this constraint and running the CCMs with emission flux surface boundary conditions for major ODSs, and allow the model itself to predict the future decadal removal of chlorine and bromine. We will perform these simulations within this project.Source gases with very long lifetimes (many hundreds to thousands of years) are too stable to affect stratospheric ozone by decomposition but they are invariably potent GHGs. For these gases loss processes in the upper atmosphere (mesosphere), which are usually ignored or treated very crudely, could significantly reduce their atmospheric lifetime, thereby decreasing their estimated climate impact. Three examples of such gases are NF3, CFC-115, and SF6. We have identified that the reactions of these gases with metallic atoms (Fe, Na and Mg) which are present in the upper mesosphere could be an important additional sink and compete with Lyman-alpha photolysis and other reactions. We will evaluate the rates of these sinks in the laboratory.For all of the gases studied, we will produce new, improved estimates of their climate impact by recalculating their GWP/GTP values.This project will use the UK's core tropospheric-stratospheric chemistry-climate model (UKCA). The testing and development work performed will lead to an improved, and more thoroughly tested, model for the UK community of researchers

发射到大气中的气体可能会持续多年甚至几个世纪。去除气体的速率取决于其所谓的寿命。因此，要了解人类活动发出的污染物气体的影响，必须准确了解其大气生命。然而，目前，许多关键污染物气体的已知寿命存在很大的不确定性。消耗的物质（ODS），例如氯氟化合物（CFC），是在平流层中分解以释放氯和溴的长寿命源气体。根据蒙特利尔方案，这些物种的排放已被淘汰，预计在接下来的50 - 100年中，臭氧层有望恢复。但是，这种恢复的速度将取决于这些气体的大气寿命及其替代品仍在发射。实际上，这些大气寿命中目前存在明显的不确定性，这些寿命都用于对未来卤素载荷的所有模型预测（通过预测的表面混合比模型边界条件）。例如，一项主要的氯氟化合物CFC-11在WMO和IPCC评估中的大气寿命为45年，尽管其他研究表明一生最多60年。最近的建立世界气候研究已经认识到这种关键的不确定性计划（WCRP）平流层过程及其在气候（SPARC）项目中的作用，以重新评估这些ODS及其替代品的寿命（例如氢氟碳碳，HFC，HFCS），使用最新的实验室数据3-D化学气候模型（CCM）。这些物种也是有效的温室气体（GHG），其已知大气寿命的变化将改变对它们将如何影响气候变化的估计值（通过其全球变暖/温度潜力（GWP/GTP）衡量）。该项目将确保英国化学气候模型（UKCA）在WCRP/SPARC重新评估中充分参与。Liftime估计直接影响对未来臭氧回收的模型预测。先前对臭氧层回收率的CCM研究已根据旧寿命估计和简单的盒子模型使用了预计的未来表面ODS浓度。因此，未来臭氧变化，平流层氯和溴荷载的主要驱动力已受到粗糙的时间依赖性边界条件的约束。可以通过删除此约束并运行具有主要ODS发射通量表面边界条件的CCM来获得臭氧回收率的更现实的表示，并允许模型本身预测未来的deCADAL去除氯和溴。我们将在该项目中进行这些模拟。终生很长的源气体（数百至数千年）太稳定了，无法通过分解来影响平流层臭氧，但它们总是有效的温室气体。对于这些气体损失过程（中层）通常被忽略或非常粗暴地处理，可能会大大降低它们的大气寿命，从而减少其估计的气候影响。此类气体的三个例子是NF3，CFC-115和SF6。我们已经确定，这些气体与上层上层中存在的金属原子（Fe，Na和Mg）的反应可能是重要的额外水槽，并与Lyman-Alpha光解和其他反应竞争。我们将评估实验室中这些水槽的速率。对于所有研究的气体，我们将通过重新计算其GWP/GTP值来产生对其气候影响的新的，改进的估计值。该项目将使用英国的核心对流层 - 间隙化学 - 气候模型（UKCA）。进行的测试和开发工作将为英国研究人员社区提供改进，更彻底的测试模型

项目成果

Determination of the atmospheric lifetime and global warming potential of sulphur hexafluoride using a three-dimensional model

使用三维模型测定六氟化硫的大气寿命和全球变暖潜力

• DOI: 10.5194/acp-2016-671
• 发表时间: 2016
• 作者: Kovács T

Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol.

• DOI: 10.1038/ncomms8233
• 发表时间: 2015-05-26
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Chipperfield, M. P.;Dhomse, S. S.;Feng, W.;McKenzie, R. L.;Velders, G. J. M.;Pyle, J. A.
• 通讯作者: Pyle, J. A.

Determination of the atmospheric lifetime and global warming potential of sulfur hexafluoride using a three-dimensional model

• DOI: 10.5194/acp-17-883-2017
• 发表时间: 2016-08
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: T. Kovács;W. Feng;Anna Totterdill;J. Plane;S. Dhomse;J. Gómez-Martín;G. Stiller;F. Haenel

Multimodel estimates of atmospheric lifetimes of long-lived ozone-depleting substances: Present and future

• DOI: 10.1002/2013jd021097
• 发表时间: 2014-03-16
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
• 影响因子: 4.4
• 作者: Chipperfield, M. P.;Liang, Q.;Tummon, F.
• 通讯作者: Tummon, F.

Revisiting the hemispheric asymmetry in midlatitude ozone changes following the Mount Pinatubo eruption: A 3-D model study.

• DOI: 10.1002/2015gl063052
• 发表时间: 2015-04-28
• 期刊: GEOPHYSICAL RESEARCH LETTERS
• 影响因子: 5.2
• 作者: Dhomse, S. S.;Chipperfield, M. P.;Feng, W.;Hossaini, R.;Mann, G. W.;Santee, M. L.
• 通讯作者: Santee, M. L.