Recent studies show that the Asian summer monsoon anticyclone (ASMA) transports emissions from the rapidly industrializing nations in Asia into the tropical upper troposphere. Here, we present a unique set of measurements on over 100 air samples collected on multiple flights of the M55 Geophysica high altitude research aircraft over the Mediterranean, Nepal, and Northern India during the summers of 2016 and 2017 as part of the European Union project StratoClim. These air samples were measured for 27 ozone‐depleting substances (ODSs), many of which were enhanced above expected levels, including the chlorinated very short‐lived substances, dichloromethane (CH₂Cl₂), 1,2‐dichloroethane (CH₂ClCH₂Cl), and chloroform (CHCl₃). CH₂Cl₂ mixing ratios in the tropopause region were 65–136 parts per trillion (ppt) in comparison to previous estimates of mixing ratios in the tropical tropopause layer of 30–44 ppt in 2013–2014. Backward trajectories, calculated with the trajectory module of the chemistry‐transport model CLaMS and driven by the ERA5 reanalysis, indicate possible source regions of CH₂Cl₂ in South Asia. We derived total equivalent chlorine (ECl), and equivalent effective stratospheric chlorine (EESC) and found that these quantities were substantially higher than previous estimates in the literature. EESC at mean age‐of‐air of 3 years based on the 2016 measurements was 1,861–1,872 ppt in comparison to a previously estimated EESC of 1,646 ppt. Our findings show that the ASMA transports larger than expected mixing ratios of long‐lived and very short‐lived ODSs into the upper troposphere and lower stratosphere, likely leading to an impact on the stratospheric ozone layer.

中文翻译：

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亚洲夏季风及其以上对流层上层和平流层下层臭氧消耗物质的航空器观测

最近的研究表明，亚洲夏季风反气旋（ASMA）将来自亚洲快速工业化国家的排放物输送到热带对流层高层。在这里，我们展示了一组独特的测量结果，这些测量是2016年和2017年夏季在M55地球物理高空研究飞机在地中海，尼泊尔和印度北部多次飞行中收集的100多个空气样本的一部分，这是欧盟StratoClim项目的一部分。对这些空气样品中的27种臭氧消耗物质（ODS）进行了测量，其中许多物质的浓度均超出了预期水平，其中包括氯化的超短寿命物质，二氯甲烷（CH ₂ Cl ₂），1,2-二氯乙烷（CH ₂ ClCH）₂ Cl）和氯仿（CHCl ₃）。与先前估计的2013-2014年热带对流层顶层混合比为30-44 ppt相比，对流层顶区域中的CH ₂ Cl ₂混合比为65-136份/万亿（ppt）。由化学传输模型CLaMS的轨迹模块计算并由ERA5重新分析驱动的后向轨迹指示CH ₂ Cl _2的可能源区域在南亚。我们得出了总当量氯（EC1）和等效有效平流层氯（EESC），发现这些数量大大高于文献中先前的估计。根据2016年的测量结果，平均航空年龄为3年的EESC为1,861-1,872 ppt，而之前估计的EESC为1,646 ppt。我们的发现表明，ASMA将长寿命和非常短寿命的ODS的混合比传送到对流层上部和平流层下部，这可能对平流层臭氧层产生影响。