Interannual variability and formation mechanism of the Asian tropopause aerosol layer and its global impact

亚洲夏季风与对流层气体（包括污染物和水蒸气）的深层对流的强烈向上输送有关。这些气体被限制在对流层上层/平流层下层（UTLS）的反气旋环流中，并对卫星仪器在该高度范围内测量的亚洲对流层顶气溶胶层（ATAL）有贡献。在夏季，亚洲只有稀疏的原位ATAL测量。阿塔尔是亚洲季风区的一个人为信号，亚洲季风区是世界上人口最稠密的地区之一，工业排放不断增加。迄今为止，从测量中只能获得有限的关于ATAL颗粒化学成分的信息。此外，辐射活性物质，如水汽和气溶胶从亚洲季风反气旋输送到北部热带外UTLS是重要的，因为这部分大气辐射收支的变化对地面气候有重大影响。由于目前缺乏对ATAL的详细了解，我们建议将原位测量的ATAL与拉格朗日输运模型（CLaMS）的模拟相结合。我们的中德项目将解决以下开放式关键问题：1)ATAL的年际和季节间变化如何？2)源区在哪里？哪些是关键的形成过程和运输途径？安乐的化学成分是什么？3)来自亚洲季风的气溶胶和水对北方温带UTLS的影响是什么？我们的中国合作伙伴拥有过去5年的ATAL原位气球测量（SWOP）的独特数据集，并建议在时间和地点上扩展他们的测量，特别是在中国污染最严重的地区之一四川盆地。此外，我们还包括美因茨大学开发的高空飞机ERICA （ERc气溶胶化学成分仪器）测量，这是迄今为止在ATAL内唯一可用的气溶胶颗粒化学成分测量。在我们的项目中，我们将把SWOP和ERICA测量与CLaMS模拟结合起来，进行轨迹计算，以推断ATAL粒子的详细运输路径，以及包括气团起源的人工示踪剂在内的全球三维模拟。CLaMS模拟将由新的ECMWF ERA-5再分析驱动，提供比旧的ERA-Interim产品更高的空间和时间分辨率。由ERA-5驱动的蛤蚌模拟是可靠地描述亚洲季风区域的输送过程及其全球影响的独特工具。我们强调，我们建议的结果可以帮助制定亚洲人为地表排放ATAL前体的法规。

The Asian summer monsoon is associated with strong upward transport by deep convection of tropospheric gases, including pollutants and water vapour. These gases are confined in the anticyclonic circulation in the Upper Troposphere / Lower Stratosphere (UTLS) and contribute to the Asian Tropopause Aerosol Layer (ATAL) measured by satellite instruments in this altitude range. Only sparse in situ ATAL measurements are available in Asia during summer. ATAL is an anthropogenic signal in the Asian monsoon region, one of the most densely populated parts of the world with increasing industrial emissions. Only limited information on the chemical composition of ATAL particles is available from measurements so far. Further, the transport of radiatively active substances such as water vapour and aerosol from the Asian monsoon anticyclone into the northern extra-tropical UTLS is important because changes of the radiative budget in this part of the atmosphere have a significant impact on surface climate.Motivated by the current lack of detailed understanding of ATAL, we propose to combine ATAL in situ measurements with simulations of a Lagrangian transport model (CLaMS). Our Sino-German project will address the following open key questions:1) How is the inter-annual and inter-seasonal variability of ATAL?2) Where are the source regions? Which are key formation processes and transport pathways? What is the chemical composition of ATAL?3) What is the impact of aerosol and H2O from the Asian monsoon to the northern extratropical UTLS?Our Chinese partners have a unique data set of in situ balloon measurements (SWOP) of ATAL from the last 5 years and propose to extend their measurements in time and locations, in particular to the Sichuan Basin one of the most heavily polluted regions in China. Further, we include high-altitude aircraft ERICA (ERc Instrument for the Chemical composition of Aerosols) measurements developed at the University of Mainz, the only available measurements of the chemical composition of aerosol particles within ATAL so far.In our project, we will combine SWOP and ERICA measurements with CLaMS simulations performing both trajectory calculations to infer detailed transport pathways of ATAL particles as well as global 3-dimensional simulations including artificial tracers of air mass origin. CLaMS simulations will be driven by the new ECMWF ERA-5 reanalysis providing a much higher spatial and temporal resolution than the older ERA-Interim product. CLaMS simulations driven by ERA-5 are a unique tool to describe transport processes reliably in the region of the Asian monsoon and its global impact. We emphasise that the results of our proposal can help to develop regulations of anthropogenic surface emissions of ATAL precursors in Asia.