Sources and Impacts of Short-Lived Anthropogenic Chlorine

平流层臭氧的消耗使更大剂量的有害太阳紫外线辐射到达地表，导致人类皮肤癌和白内障的增加以及其他影响，如农作物受损。臭氧还影响到地球的辐射平衡，特别是平流层下部的臭氧消耗产生了重要的气候强迫。虽然大多数寿命较长的消耗臭氧层物质（如氟氯化碳）现在都受到《联合国蒙特利尔议定书》的控制，而且其丰度正在缓慢下降，但臭氧层恢复的速度仍然存在很大的不确定性。LS的变化可能导致臭氧恢复延迟，甚至进一步消耗，也可能对气候产生重要影响。气象组织/环境署2014年平流层臭氧消耗评估中强调的一个关键不确定性是，不受控制的含氯极短寿命物质（VSLS）的重要性日益增加，这些物质可能到达LS并造成臭氧消耗。人为氯化VSLS（Cl-VSLS）的意外和不明原因的增加，特别是在东亚和东南亚。其中一些Cl-VSLS将通过热带的深层对流（通过热带对流层顶）或通过亚洲夏季风（ASM）或东亚冬季风到达平流层。《蒙特利尔议定书》可以说是世界上最成功的环境协议。通过控制长寿命消耗臭氧层物质的生产和排放，它使臭氧层走上了恢复之路。然而，寿命短的卤代化合物（寿命<6个月）迄今尚未被列入，因为人们认为它们的数量不多，也不持久，不足以产生影响。最近的观测表明情况并非如此;本提案中的计算表明，Cl-VSLS可能会将南极臭氧洞的恢复（恢复到1980年的水平）推迟30年。幸运的是，《蒙特利尔议定书》有一个定期审查程序，允许修正案处理对臭氧层和气候的新威胁，例如，最近在2016年成功地限制了氢氟碳化物（HFC）的生产。该提案利用了UEA在大气卤烃测量方面的传统，以获得关键的E/SE亚洲地区和全球中部地区氯化合物的新观测结果。对流层上部地面观测将在关键的冬季进行，届时我们将能够检测到来自中国的污染排放，中国可能是全球Cl-VSLS的主要排放国。我们将扩展目前由CARIBIC在役全球客机测量的气体套件，以包括几种新确定的VSLS。这将使我们能够在更广泛的地理区域内调查这些VSLS的分布，以确定源区域并评估其大气丰度的长期变化。我们的观测结果将与利兹和兰开斯特的详细三维建模相结合，他们拥有世界领先的大气氯研究专业知识和工具。其中一个模型将用于“逆”模式，以追溯到其源区的人为VSLS的观测。总体而言，这些模型将用于量化卤化臭氧消耗气体流入平流层的情况，并确定其对臭氧和气候的影响。我们将计算臭氧消耗和气候变化的指标，并与专家合作伙伴合作，将这些指标纳入决策过程（蒙特利尔议定书）。SISLAC的结果将为今后的国际评估，例如气象组织/环境规划署和气候小组的报告提供重要信息。

Depletion of stratospheric ozone allows larger doses of harmful solar UV radiation to reach the surface leading to increases in skin cancer and cataracts in humans and other impacts, such as crop damage. Ozone also affects the Earth's radiation balance and, in particular, ozone depletion in the lower stratosphere (LS) exerts an important climate forcing. While most long-lived ozone-depleting substances (e.g. CFCs) are now controlled by the United Nations Montreal Protocol and their abundances are slowly declining, there remains significant uncertainty surrounding the rate of ozone layer recovery. Changes in the LS may cause delayed ozone recovery or even additional depletion, and can also have important effects on climate. One key uncertainty, highlighted in the WMO/UNEP 2014 Assessment of Stratospheric Ozone Depletion, is the increasing importance of uncontrolled chlorine-containing very short-lived substances (VSLS) which can reach the LS and cause ozone depletion.While significant amounts of brominated VSLS are known to be emitted naturally from the oceans, recent publications also show a rapid, unexpected and unexplained increase in anthropogenic chlorinated VSLS (Cl-VSLS), especially in E and SE Asia. Some of these Cl-VSLS will reach the stratosphere via deep convection in the tropics (through the tropical tropopause layer) or via the Asian Summer Monsoon (ASM) or the E Asian Winter Monsoon.The Montreal Protocol is arguably the world's most successful environmental agreement. By controlling the production and emission of long-lived ODSs, it has set the ozone layer on the road to recovery. However, short-lived halogenated compounds (lifetimes <6 months) have so far not been included, based on the belief that they would not be abundant or persistent enough to have an impact. Recent observations suggest otherwise; calculations in this proposal suggest that Cl-VSLS may delay the recovery of the Antarctic Ozone Hole (to 1980 levels) by up to 30 years. Fortunately, the Montreal Protocol has a regular review process which allows amendments to deal with new threats to the ozone layer and climate, e.g. the recent 2016 success of including limits to the production of hydrofluorocarbons (HFCs).This proposal takes advantage of UEA's heritage in atmospheric halocarbon measurements to obtain novel observations of chlorine compounds in the key E/SE Asia region and in the global mid-upper troposphere. Surface observations will be targeted in the key winter periods when we know that we will be able to detect polluted emissions from China, a likely major emitter of Cl-VSLS globally. We will extend the suite of gases currently measured by the CARIBIC in-service global passenger aircraft to include several newly-identified VSLS. This will allow us to investigate the distribution of these VSLS over a much wider geographical area, to identify source regions and to assess longer term changes in their atmospheric abundance.Our observations will be combined with detailed 3-D modelling at Leeds and Lancaster, who have world-leading expertise and tools for the study of atmospheric chlorine. One model will be used in an 'inverse' mode to trace back the observations of anthropogenic VSLS to their source regions. Overall, the models will be used to quantify the flux of halogenated ozone-depleting gases to the stratosphere and to determine their ozone and climate impact. We will calculate metrics for ozone depletion and climate change and feed these through to the policy-making process (Montreal Protocol) with the collaboration of expert partners. The results of SISLAC will provide important information for future international assessments e.g. WMO/UNEP and IPCC reports.