Abstract. Tropopause-overshooting convection in the midlatitudes provides a rapid transport pathway for air from the lower troposphere to reach the upper troposphere and lower stratosphere (UTLS) and can result in the formation of above-anvil cirrus plumes (AACPs) that significantly hydrate the stratosphere. Such UTLS composition changes alter the radiation budget and impact climate. Novel in situ observations from the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field campaign are used in this study to examine UTLS impacts from AACP-generating overshooting convection. Namely, a research flight on 31 May 2022 sampled active convection over the state of Oklahoma for more than 3 h with the NASA ER-2 high-altitude research aircraft. An AACP was bisected during this flight, providing the first such extensive in situ sampling of this phenomenon. The convective observations reveal pronounced changes in air mass composition and stratospheric hydration up to altitudes of 2.3 km above the tropopause and concentrations more than double background levels. Unique dynamic and trace gas signatures were found within the AACP, including enhanced vertical mixing near the AACP edge and a positive correlation between water vapor and ozone. Moreover, the water vapor enhancement within the AACP was found to be limited to the saturation mixing ratio of the low temperature overshoot and AACP air. Comparison with all remaining DCOTSS flights demonstrates that the 31 May 2022 flight had some of the largest tropospheric tracer and water vapor perturbations in the stratosphere and within the AACP.

中文翻译：

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机载观测对流层上部和平流层下部在产生砧座卷云羽流的活跃对流中的成分变化


摘要。中纬度地区的对流层顶过冲对流为空气从对流层下部到达对流层上部和平流层下部（UTLS）提供了快速输送路径，并可能导致砧上卷云羽（AACP）的形成，从而使平流层显着水合。这种 UTLS 成分的变化会改变辐射预算并影响气候。本研究使用 NASA 夏季平流层动力学和化学 (DCOTSS) 现场活动的新颖现场观测来检验 AACP 产生的超调对流对 UTLS 的影响。也就是说，2022 年 5 月 31 日的一次研究飞行使用 NASA ER-2 高空研究飞机对俄克拉荷马州上空的活跃对流进行了超过 3 小时的采样。 AACP 在这次飞行中被一分为二，首次对这种现象进行了如此广泛的现场采样。对流观测揭示了对流层顶以上 2.3 公里高度处空气质量成分和平流层水合作用的显着变化，浓度是背景水平的两倍以上。在 AACP 内发现了独特的动态和痕量气体特征，包括 AACP 边缘附近增强的垂直混合以及水蒸气和臭氧之间的正相关性。此外，AACP 内的水蒸气增强被发现受限于低温过冲和 AACP 空气的饱和混合比。与所有剩余的 DCOTSS 航班进行比较表明，2022 年 5 月 31 日的航班在平流层和 AACP 内出现了一些最大的对流层示踪剂和水蒸气扰动。