The Role of Short-lived Species in the Tropical Atmosphere

卤素是大气化学中的重要成分，影响平流层和对流层的臭氧浓度。目前，向平流层供应极短寿命的卤素是平流层溴预算中的一个主要不确定性，它提供了高达总溴负载量的20%。未来对平流层的供应可能会受到海洋表面温度升高和对流引起的VSLH排放与气候有关的变化的影响。VSLH排放也可以在决定臭氧浓度方面发挥很大作用，因为高水平的BrO可能会导致边界层和自由对流层中的臭氧耗尽。需要大大加强对影响VSLH排放和大气浓度的海洋、化学和气候因素的了解，以预测它们在未来几十年气候变化中的重要性。热带地区面积大、对流强度大、海洋产量高，这一点至关重要。在热带太平洋和大西洋观测到CHBr3、CH2Br2和其他VSLH的高值，为排放热点在其他原始大气中的重要性提供了证据。西太平洋大气中VSLH浓度的测量将在2008-2012年间根据最近授予的国家环境研究中心拨款进行，我是这项拨款的首席研究员。这些时间序列是连续的，具有很高的时间分辨率，将形成该地区VSLH的独特记录。测量数据的收集和解释为我们理解科学问题提供了一个极好的机会，这些问题包括卤素在全球氧化能力中的作用以及碘碳化物在热带这一区域海洋边界层的气溶胶和云的产生中的作用。我将扩大我在VSLH测量方面的研究兴趣，以提供更多关于短期卤代烃和碳氢化合物如何影响热带对流层和平流层的知识和理解。新的连续测量将与其他测量一起解释，主要是在加州大学欧文分校收集的频率较低但20年来的记录。结合气象和当地海洋记录对卤代烃数据进行联合解释，将使人们能够了解厄尔尼诺现象和马登-朱利安振荡等气候特征的影响。这些对现有数据和新数据的分析将用于设计使用NCAS/Met Office UKCA模型的模型研究。数据分析和解释将扩大到包括现有站点(Mace Head、佛得角、Weyborne以及AGAGE和NOAA网络中的站点)以及PEM系列和OP3等热带活动的测量结果。这里开发的测量系统具有强大的自主仪器，在远程站点运行，人为干预最少，具有很大的扩展潜力，以包括基于相同理念的其他仪器，我将通过开发和部署其他强大的仪器包来扩展测量，以供自主使用。从大气的角度来看，西太平洋在未来几十年将是令人着迷的。由于自然栖息地的变化和工业化程度的提高，VSLH和碳氢化合物的排放可能会发生重大变化。由于受到太平洋上空原始空气的强烈影响，该地区的化学混合物将以目前无法预测的方式演变，排放、化学、气象和海洋条件都可能发生重大变化。总体而言，我将建立一个世界领先的方案，解释各种测量方法，以了解卤代烃和碳氢化合物在该区域和全球大气层中的作用。一旦发展起来，这种解释性的专门知识就可以用来解决更广泛的大气变化问题。

The halogens are vital components in the chemistry of the atmosphere, influencing ozone concentrations in the stratosphere and the troposphere. Currently, the supply of very short-lived halocarbons (VSLH) to the stratosphere is a major uncertainty in the stratospheric bromine budget, with VSLH providing up to 20% of the total bromine loading. The future supply to the stratosphere will likely be affected by climate-related changes in the emissions of VSLH arising from increases in sea surface temperatures and convection. VSLH emissions can also play a large role in determining O3 concentrations as high BrO levels could lead to depletion of O3 in the boundary layer and free troposphere. A significantly improved understanding of the marine, chemical and climatic factors affecting VSLH emission and atmospheric concentration is required to predict their importance as climate changes in the coming decades. The tropics with its large area, regions of convective intensity and highly productive oceans is critical. High values of CHBr3, CH2Br2 and other VSLH have been observed in the tropical Pacific and Atlantic oceans, providing evidence for the importance of emission hotspots in otherwise pristine atmospheres. Measurements of atmospheric concentrations of VSLH in the Western Pacific will be made from 2008-2012 under a recently awarded NERC grant on which I am the Principal Investigator. These time series will form a unique record of VSLH in this region, as they are continuous and highly time-resolved. The collection and interpretation of the measurements provide an excellent opportunity to make real breakthroughs in our understanding of scientific issues including the role of halogens in the global oxidative capacity and the role of iodocarbons in the production of aerosols and clouds in the marine boundary layer in this region of the tropics. I will broaden my research interests in the measurement of VSLH to provide increased knowledge and understanding of how short-lived halocarbons and hydrocarbons influence the tropical troposphere and stratosphere. The new, continuous measurements will be interpreted together with other measurements, principally the less frequent but 20 year record collected at the Univ Calif Irvine. Joint interpretation of the halocarbon data with meteorological and local marine records will enable the influence of climatic features such as El Nino and the Madden Julian Oscillation to be understood. These analyses of existing and new data will be used to design model studies using the NCAS/Met Office UKCA model. Data analysis and interpretation will be extended to include measurements from existing stations (Mace Head, Cape Verde, Weyborne and those in the AGAGE and NOAA networks) and from tropical campaigns such as the PEM series and OP3. The measurement system developed here with robust, autonomous instruments operating at remote sites with minimal human intervention has great potential to be extended to include other instruments based on the same philosophy and I will extend the measurements made by developing and deploying other robust instrument packages for autonomous use. From an atmospheric perspective, the West Pacific will be fascinating over the coming decades. Emissions of VSLH and hydrocarbons are likely to change significantly as a result of changes to natural habitats and increased industrialisation. The chemical mix in this region, strongly affected as it is by the pristine air over the Pacific Ocean itself, will evolve in a currently unpredictable way, with emissions, chemistry, meteorology and oceanic conditions all likely to change significantly. Overall, I will establish a world-leading programme interpreting measurements to understand the role of halo- and hydrocarbons in this region and in the global atmosphere. Once developed, this interpretative expertise can be used to address a much broader range of atmospheric change issues.