Long-lived greenhouse gases in the extra-tropical tropopause region

由于持续的有害排放，大气中最相关的长期温室气体的混合比例不断增加。最主要的温室气体是二氧化碳(CO2)、甲烷(CH4)和一氧化二氮(N2O)。除了它们作为强大的气态气候力量的相关性外，这些气体在对流层顶上表现出强烈的梯度，因此适合作为大气输送过程的示踪剂。六氟化硫(SF6)的大气寿命约为850年，混合比不断增加，经常被用作空气年龄的示踪剂，这是平流层空气质量输送的指示器。拟议的项目旨在协调和科学评估来自IAGOS-CARIBIC观测平台的对流层顶区现有测量结果，这些测量结果包括这四种主要温室气体和具有高全球变暖潜力的长寿命卤化痕量气体。数据涵盖2005-2020年期间，作为项目的一部分，将与德国研究飞机Halo上测量的更多现有数据结合起来。数据分析将针对对流层上层温室气体混合比率的趋势，特别是其与地面观测的时间滞后、对流层顶区域长期温室气体的可变性以及在对流层上层遇到的高混合比率的确定和来源归属。总体目标是更好地了解进入和进入对流层顶区域的大气输送过程。此外，现有的基于气相色谱(GC)和质谱联用的检测空气样品中微量卤化气体的实验室装置将扩大，增加一个小型GC装置，以最大限度地减少样品体积消耗来检测SF6。该项目计划建议调查以脉冲放电探测器为基础的SF6非放射性检测的各种备选方案。这种探测器一般适用于SF6的测量，但到目前为止还没有用于大气中SF6的测量。或者，可以预见已建立的使用电子捕获探测器的检测(基于镍同位素的放射性衰变)。

Mixing ratios of the most relevant long-lived greenhouse gases keep increasing in the atmosphere due to ongoing athprogenic emissions. The most dominant greenhouse gases are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). In addition to their relevance as potent gaseous climate forces, these gase exhibit strong gradients across the tropopause and are therefore suited as tracers for atmospheric transport processes. With an atmospheric lifetime of approximately 850 years and continuisly increasin mixing ratios, sulfur hexafluoride (SF6) is frequently used as a tracer of the age of air, an indicator of air mass transport in the stratosphere.The proposed project aims at the harmonization and scientific evaluation of existing measurements from the tropopause region from the IAGOS-CARIBIC observational platform of these four main greenhouse gases and long-lived halogenated trace gases with high global warming potentials. Data cover the period 2005-2020 and as part of the project will be combined with further existing data from measurements onbard the German research aircraft HALO. Data analysis will target trends of greenhouse gas mixing ratios in the upper troposphere, in particular their time lags to ground observations, the variability of long-lived greenhouse gases in the tropopause region, and the identification and source attribution of high mixing ratios encountered in the upper troposphere. The overalll aim is an improved understanding of atmospheric transport processes in and into the tropopause region.In addition, an existing laboratory set-up for detection of halogenated trace gases in air samples based on gas chromatography (GC) coupled with mass spectrometry is to be extended with a small GC unit for detection of SF6 at minimized sample volume consumption. The project plan proposes to investigate options for the non-radioactive detection of SF6 based on pulsed discharge detectors. Such detectors are generally suited for measurements of SF6 but have up to now not been used for measurement of SF6 in the atmosphere. Alternatively, the established detection with an electron capture detector (based on radioactive decay of a Nickel isotope) is foreseen.