Continuing Measurements of Water Vapor, Clouds, Aerosol, and Waves Above, and Across, the Tropical Tropopause Layer with in Situ Instruments on Circum-Tropical Isopycnic Balloons

使用环热带等密度气球上的现场仪器持续测量热带对流层顶层上方和上方的水蒸气、云、气溶胶和波浪

• 批准号: 2336110
• 负责人: Terry Deshler
• 金额: $ 120.18万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-15 至 2027-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2336110&HistoricalAwards=false
• 关键词: Continuing; Measurements; Water; Vapor; Clouds

This award supports the continued participation of the Principal Investigators (PIs) in the Strateole-2 field campaign, organized by the French space agency (CNES, for Centre National d'Etudes Spatiales) and the Laboratory for Dynamic Meteorology (LMD) at the University of Paris-Saclay. The campaign makes observations of the tropical tropopause layer (TTL), the layer of the atmosphere from roughly 14km to 18km between the tropical troposphere and stratosphere, using balloons designed to float at a constant altitude for flights of up to 3 months. The balloons are launched from the Seychelles and float around the equator at the top of the TTL (near 18km) or in the lower stratosphere at an altitude close to 20km. Strateole-2 was planned as a set of three deployments, a preliminary engineering deployment with 8 balloon flights followed by two science deployments with 20 flights each. The first two deployments took place in 2019 and 2021 and funds for the PIs' participation in these deployments were provided through AGS-1643022. Funds provided here support participation in the third campaign, scheduled to begin in October 2025.The primary task under this award is the production of balloon-borne instruments to observe temperature, moisture, aerosols, and cirrus cloud ice particles. One instrument is the LASP Particle Counter (LPC), named for the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. The LPC flies on the balloon gondola and detects aerosols and ice particles using laser backscatter. It can determine the concentration of particles of sizes ranging from 0.3 to 30 microns in 32 size bins. The LPC is accompanied by a moisture and temperature sensor developed for use in weather balloons, the Vaisala RS41, which can detect moisture at the low humidities found in the TTL and lower stratosphere. Five LPCs will be flown in the 2025 deployment, three at 18km and two at 20km.A second instrument is the Reeldown Aerosol, Cloud, Humidity and Temperature Sensor (RACHuTS), a 2kg package which is reeled up and down on a cord to generate soundings extending 2km below the balloon. RACHuTS integrates the Thermodynamic SENsor (TSEN, developed by a French team) with a smaller version of the LPC called the ROPC (RACHuTS Optical Particle Counter, with 8 size bins from 0.3 to 10 microns), along with an RS41 and the Tunable Diode Laser (TDL) moisture sensor developed under AGS-2233136. TDL is an improvement over the FLASH-B moisture sensor used in the previous deployments since it is not sensitive to ambient light and can thus be used during the day, doubling the opportunities for profiling. RACHuTS makes profiles with one meter vertical resolution, with one profile as it descends and another as it returns to the gondola. Three RACHuTS profilers will be flown in the 2025 deployment, all at 18km.As in the earlier deployments the measurements taken using LPC and RACHuTS will be used to address three issues in TTL science. The first is the extent to which supersaturation is an important factor in determining humidity in the stratosphere. Stratospheric humidity is thought to be limited by the saturation vapor pressure at the coldest temperature air encounters as it rises through the TTL to enter the stratosphere, under the assumption that water vapor condensation or deposition occurs when relative humidity reaches 100%. But data from previous deployments shows relative humidities above 150%, suggesting that the cold point saturation vapor pressure may not be as strict a limit as previously supposed. A related issue is the role of atmospheric waves in the formation of cirrus clouds in the TTL, as previous RACHuTS deployments and other evidence suggests that the majority of ice particle layers within the TTL are generated by cooling associated with rising motions in waves. The layers can be quite thin, perhaps only 10 meters, thus the one meter resolution of RACHuTS profiles is necessary to observe the layers. The third issue to be addressed in the project is the finding of layers of large particles, in the size range from 2 to 20 microns, at relative humidities too low to allow ice formation. The nature of these particles has yet to be determined. One strategy for studying them is to fly the LPC on two balloons at the 20km level, which is above the TTL and typically too warm and dry to support ice clouds. The detection of super-micron particles at that level would be a strong argument that the particles are not composed of ordinary ice.The work has scientific broader impacts due to the unique dataset to be collected, in particular the long sampling time, high vertical resolution, and high quality of the observations. RACHuTS and LPC observations will be made freely available to the research community so that they can be used in ways not anticipated here. In addition, the project develops novel technologies for meteorological observations that could have a wide array of scientific applications. Beyond these considerations, the project supports a postdoctoral research associate, thereby developing the future scientific workforce in this research area. The project develops a substantial international collaboration and also provides support and training to a research scientist and an undergraduate student at the University of Colorado.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.

该奖项支持主要调查员继续参与法国航天局（法国国家空间研究中心）和巴黎-萨克雷大学动态气象学实验室组织的“卫星-2”实地活动。该活动使用设计为在恒定高度漂浮长达3个月的气球，对热带对流层和平流层之间约14公里至18公里的大气层热带对流层顶层进行观测。 这些气球从塞舌尔群岛发射，在TTL顶部（近18公里）的赤道周围漂浮，或在平流层下部接近20公里的高度漂浮。 气球-2计划作为一组三个部署，初步工程部署8气球飞行，其次是两个科学部署，每个20飞行。前两次部署分别于2019年和2021年进行，PI参与这些部署的资金通过AGS-1643022提供。 这里提供的资金支持参与第三次活动，计划于2025年10月开始。该奖项的主要任务是生产气球携带的仪器，以观察温度，湿度，气溶胶和卷云冰粒。 其中一种仪器是LASP粒子计数器（LPC），以科罗拉多大学博尔德分校的大气和空间物理实验室命名。 LPC在气球吊舱上飞行，并使用激光后向散射检测气溶胶和冰粒。它可以在32个尺寸箱中确定尺寸范围为0.3至30微米的颗粒的浓度。 LPC配备了一个用于气象气球的湿度和温度传感器，Vaisala RS 41，它可以在TTL和平流层较低的低湿度下检测湿度。 在2025年的部署中，将有五个LPC飞行，三个在18公里处，两个在20公里处。第二个仪器是Reeldown气溶胶，云，湿度和温度传感器（RACHuTS），这是一个2公斤的包裹，它在一根绳子上上下滚动，以产生在气球下方2公里处的探测。 RACHuTS集成了热力学传感器（TSEN，由法国团队开发）与称为ROPC（RACHuTS光学粒子计数器，具有0.3至10微米的8个尺寸箱）的LPC的较小版本，沿着RS 41和根据AGS-2233136开发的可调谐二极管激光（TDL）湿度传感器。 TDL是对先前部署中使用的FLASH-B湿度传感器的改进，因为它对环境光线不敏感，因此可以在白天使用，使分析的机会增加一倍。 RACHuTS可以制作垂直分辨率为一米的剖面图，一个剖面图是下降时的剖面图，另一个剖面图是返回到吊舱时的剖面图。 在2025年的部署中，三个RACHuTS剖面仪将在18公里的高度飞行。与早期的部署一样，使用LPC和RACHuTS进行的测量将用于解决TTL科学中的三个问题。 首先是过饱和度在多大程度上是决定平流层湿度的一个重要因素。 平流层湿度被认为是由饱和蒸汽压在最冷的温度空气遇到的限制，因为它上升通过TTL进入平流层，假设水蒸气冷凝或沉积发生时，相对湿度达到100%。 但是以前部署的数据显示相对湿度高于150%，这表明冷点饱和蒸汽压可能没有以前假设的那么严格。 一个相关的问题是大气波在TTL卷云形成中的作用，因为之前的RACHuTS部署和其他证据表明，TTL内的大多数冰粒层是由与波浪上升运动相关的冷却产生的。 这些层可能非常薄，可能只有10米，因此RACHuTS剖面的1米分辨率对于观察这些层是必要的。 该项目要解决的第三个问题是发现大颗粒层，尺寸范围从2到20微米，相对湿度太低，无法形成冰。这些粒子的性质尚未确定。 研究它们的一个策略是在20公里高度的两个气球上飞行LPC，这是在TTL之上，通常太温暖和干燥，无法支撑冰云。 在这个水平上探测到超微米粒子将有力地证明这些粒子不是由普通的冰组成的。由于要收集的独特数据集，特别是长采样时间，高垂直分辨率和高质量的观测，这项工作具有更广泛的科学影响。RACHuTS和LPC观测将免费提供给研究界，以便它们可以以本文未预期的方式使用。此外，该项目还开发了气象观测新技术，这些技术可能具有广泛的科学应用。除了这些考虑因素，该项目还支持博士后研究助理，从而发展该研究领域未来的科学劳动力。 该项目发展了实质性的国际合作，并为科罗拉多大学的一名研究科学家和一名本科生提供了支持和培训。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。