Strateole-2: Atmospheric Wave Influences on Cirrus, Water Vapor, and Global Circulation Near the Tropical Tropopause

该奖项支持对在2019年/2020年(8次飞行)和2021/2022年(17次飞行)冬季进行的Strateole-2野战的前两次部署中收集的观察结果进行的分析。Strateole-2是一项长期的气球运动，由法国国家空间研究中心(CNES)组织。这些气球是从塞舌尔发射的，随着平流层下部的风在赤道周围漂移了长达两个月的时间。该活动使用了各种仪器来观测热带对流层顶层(TTL)，这是对流层(云、降水和天气系统的范围)和平流层(其上方包含臭氧层的寒冷和干燥地区)之间的过渡区。Strateole-2的主要焦点是重力波，这意味着大气中的波动，其主要恢复力是重力。这种波是由热带海洋上的深对流云中发生的垂直运动产生的，但它们的水平波长可以比对流系统大得多，在纬度上有足够的程度受到科里奥利力及其随纬度的变化的影响。这些波动之所以令人感兴趣，是因为它们提供了水平动量的垂直输送，从而驱动了准两年振荡(QBO)，即赤道平流层风的逆转，从高水平开始，并在接下来的两年里下降。波动中的上下运动也影响TTL的温度，在向上位移中出现的较低温度促进了周围水蒸气的凝结，促进了薄卷云的形成，从而阻止了向外发出的红外辐射，从而对地球的能量平衡产生了影响。卷云中冰粒的形成还减少了进入平流层的水蒸气的数量，这对行星能量平衡有额外的影响。这里的工作专门针对水平波长可能为1000公里的长波，但浅波，垂直波长不到一公里，周期为几天。该项目利用了美国国家科学基金会资助的部署中使用的一套仪器，包括根据AGS-1642650支持的无线电掩星接收器(ROC)，根据AGS-1642277开发的光纤温度剖面仪(FLOATS)，以及根据AGS-1643022开发的卷带式仪器组件(RACHUTS)。它还使用了法国研究人员开发的仪器的数据，包括气球载激光雷达(BeCOOL)和红外水蒸气传感器(PicoSTRAT)，以及机载温度计、气压计和GPS接收器。这些数据源与卫星数据和再分析产品结合使用，并由欧洲中期天气预报中心的非资助合作者执行具有增强垂直分辨率的专门模拟。一个需要解决的问题是这些煎饼状波的产生，尽管它们有很长的水平波长，但它们一定是由局部对流产生的。动量输送方面的工作考虑了波浪破裂和随后产生的湍流，以及波动量通量的计算。这项工作具有更广泛的影响，因为它有可能改善QBO在用于长期天气预报的模式中的表示。模式很难描述QBO，部分原因是很难描述重力波动量输送的影响，而QBO在调制潜在的可预测形式的亚季节天气变化方面发挥着重要作用。此外，卷云和平流层水汽的辐射效应是理解和预测人为气候变化的重要因素之一。此外，PIs还通过参与纠正社交媒体中的科学误解的努力，开展公共宣传和教育，与同事合作开发易于使用的教程，使用户能够获得科学数据和信息。该项目为博士后研究员提供支持和培训，从而促进该研究领域的科学队伍。该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award supports analysis of observations collected in the first two deployments of the Strateole-2 field campaign, which took place in the winters of 2019/2020 (8 flights) and 2021/2022 (17 flights). Strateole-2 is a long-duration ballooning campaign organized by the Centre National d'Etudes Spatiales (CNES), the French national space agency. The balloons were launched from the Seychelles and drifted around the equator for up to two months following the winds of the lower stratosphere. The campaign used a variety of instruments to observe the tropical tropopause layer (TTL), the transition zone between the troposphere (the domain of clouds, precipitation, and weather systems) and the stratosphere (the cold and dry region above it which contains the ozone layer). A primary focus of Strateole-2 is gravity waves, meaning wave motions in the atmosphere for which the primary restoring force is gravity. Such waves are generated by vertical motions occurring in the deep convective clouds over tropical oceans but they can have horizontal wavelengths much larger than convective systems, with sufficient extent in latitude to be affected by the Coriolis force and its variation with latitude. These waves are of interest because they provide the vertical transport of horizontal momentum which drives the quasi-biennial oscillation (QBO), a reversal of the winds in the equatorial stratosphere that starts at high levels and descends over the next two years. The up-and-down motions in the waves also affect the temperature of the TTL, and the colder temperatures occurring in the upward displacements promote the condensation of ambient water vapor, promoting the formation of thin cirrus clouds which block outgoing infrared radiation and thus have an effect on Earth's energy balance. The formation of ice particles in cirrus clouds also reduces the amount of water vapor entering the stratosphere, where it has additional effects on the planetary energy balance.Work performed here focuses specifically on waves which are long, with horizontal wavelengths of perhaps 1,000km, but shallow, with vertical wavelengths less than a kilometer, and periods of a few days. The project takes advantage of the NSF-funded suite of instruments flown in the deployments, including the radio occultation receiver (ROC) supported under AGS-1642650, the fiber optic temperature profiler (FLOATS) developed under AGS-1642277, and the reel-down instrument package (RACHuTS) developed under AGS-1643022. It also uses data from instruments developed by researchers in France, including a balloon-borne lidar (BeCOOL) and an infrared water vapor sensor (PicoSTRAT), as well as onboard thermometers, barometers, and GPS receivers. These data sources are used in combination with satellite data and reanalysis products, and specialized simulations with enhanced vertical resolution are performed by unfunded collaborators at the European Centre for Medium-Range Weather Forecasts. One issue to be addressed is the generation of these pancake-like waves, which must somehow be generated by localized convection despite their long horizontal wavelengths. Work on momentum transport considers wave breaking and subsequent generation of turbulence as well as the calculation of wave momentum flux.The work has broader impacts through its potential for improving the representation of the QBO in models used for long-range weather prediction. Models have difficulty representing the QBO, in part due to the difficulty of representing the effect of gravity wave momentum transport, and the QBO plays important roles in modulating the potentially predictable forms of subseasonal weather variations. In addition, the radiative effects of cirrus clouds and stratospheric water vapor are among the factors that matter for understanding and anticipating anthropogenic climate change. In addition, the PIs conduct public outreach and education by participating in an effort to correct scientific misunderstanding in social media, working with colleagues to develop easy-to-use tutorials that give users access to scientific data and information. The project provides support and training to a postdoctoral fellow, thereby promoting the scientific workforce in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.