Abstract. Extreme convective events in the troposphere not only have immediate impacts on the surface, they can also influence the dynamics and composition of the lower stratosphere (LS). One major impact is the moistening of the LS by overshooting convection. This effect plays a crucial role in climate feedback as small changes of water vapor in the upper troposphere and lower stratosphere (UTLS) have a large impact on the radiation budget of the atmosphere. In this case study, we investigate water vapor injections into the LS by two consecutive convective events in the European mid-latitudes within the framework of the MOSES (Modular Observation Solutions for Earth Systems) measurement campaign during the early summer of 2019. Using balloon-borne instruments, rare measurements of the convective water vapor injection into the stratosphere were performed. The magnitude of the water vapor reached up to 12.1 ppmv with an estimated background value of 5 ppmv. Hence it is in the same order of magnitude as earlier reports of water vapor injection by convective overshooting above North America. However the overshooting took place in the extra-tropical stratosphere and has an impact on long-term water vapor mixing ratios in the stratosphere compared to the Monsoon-influenced region in North America. At the altitude of the measured injection, a sharp drop in a local ozone enhancement peak makes the observed composition of air very unique with high ozone up to 696 ppbv and high water vapor up to 12.1 ppmv. While ERA-Interim data does not show any signal of the convective overshoot, the measured values in the LS are underestimated by MLS satellite data and overestimated by ERA5 reanalysis data. Backward trajectories of the measured injected air masses reveal that the moistening of the LS took place several hours before the balloon launch. This is in good agreement with reanalyses and satellite data showing a strong change in the structure of isotherms, and a sudden and short-lived increase in potential vorticity at the altitude of the trajectory, as well as low cloud top brightness temperatures during the overshooting event.

中文翻译：

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2019年欧洲低中纬度平流层强对流风暴对水汽混合比影响的案例研究

摘要。对流层中的极端对流事件不仅会对地表产生直接影响，还会影响平流层下部 (LS) 的动态和组成。一个主要影响是超调对流对 LS 的润湿。这种效应在气候反馈中起着至关重要的作用，因为对流层上层和平流层下层 (UTLS) 中水汽的微小变化对大气的辐射收支有很大影响。在本案例研究中，我们调查了 2019 年初夏在 MOSES（地球系统模块化观测解决方案）测量活动框架内，欧洲中纬度地区两次连续对流事件向 LS 注入的水蒸气。使用气球-运载仪器，罕见地对注入平流层的对流水蒸气进行了测量。水蒸气的量级高达 12.1 ppmv，估计背景值为 5 ppmv。因此，它与早先关于北美上空对流超调注入水蒸气的报告处于同一数量级。然而，与北美受季风影响的地区相比，超调发生在温带平流层，并且对平流层中长期的水汽混合比有影响。在测量注入的高度，局部臭氧增强峰值的急剧下降使得观察到的空气成分非常独特，臭氧高达 696 ppbv，水蒸气高达 12.1 ppmv。虽然 ERA-Interim 数据没有显示任何对流超调信号，但 LS 中的测量值被 MLS 卫星数据低估，而被 ERA5 再分析数据高估。测量的注入空气质量的向后轨迹表明，LS 的润湿发生在气球发射前几个小时。这与再分析和卫星数据显示出等温线结构的强烈变化、轨迹高度处潜在涡度的突然和短暂增加以及过冲事件期间的低云顶亮温非常吻合.