Collaborative Research: Tropical waves and their effects on circulation from 3D GPS radio occultation sampling from stratospheric balloons in Strateole-2

合作研究：热带波及其对 Strateole-2 平流层气球 3D GPS 无线电掩星采样的环流影响

• 批准号: 1642644
• 负责人: M Joan Alexander
• 金额: $ 37.27万
• 依托单位: NorthWest Research Associates, Incorporated
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1642644&HistoricalAwards=false
• 关键词: Collaborative; Research; Tropical; waves; their

The tropical upper troposphere and lower stratosphere are home to a variety of wave motions which play key roles in weather, climate, and atmospheric circulation. Waves which are broad (horizontal wavelengths spanning several degrees latitude) but shallow (vertical wavelengths of about one to four kilometers), generated by large areas of tropical convection, are the subject of this investigation. These waves are of interest for three reasons: first, the waves can induce the formation of cirrus clouds in the tropical tropopause layer (TTL), the transition zone between the troposphere and stratosphere that extends from about 14km to 18.5km. TTL cirrus can form as rising air motions associated with the waves depress air temperatures and cause water vapor to freeze out as cirrus ice crystals. The resulting clouds may be too thin to see from the ground or from satellites, yet they have an important climatic effect as they trap outgoing infrared radiation and thus warm the atmosphere. The prevalence of such clouds is difficult to quantify, and the relative importance of wave motions as a source of TTL cirrus, in comparison to cirrus formation due to outflow of ice particles from deep cumulus clouds, is not known.Second, the freezing out of water vapor by wave-induced temperature depression could be an important constraint on the amount of water vapor entering the stratosphere. The TTL is sometimes referred to as the "gateway to the stratosphere", as most of the water vapor in the stratosphere over the entire globe enters through the TTL. The stratosphere is extremely dry compared to the troposphere, but stratospheric water vapor is nevertheless important as it has a relatively strong greenhouse effect and can lead to the formation of the polar stratospheric clouds which are key to the formation of the ozone hole.Third, waves can transport momentum from the troposphere to the stratosphere, and wave momentum transport is the primary driver of the stratospheric Quasi-Biennial Oscillation (QBO), an alternation between easterly and westerly winds occurring over the global tropics with a cycling time in excess of two years. While the QBO is narrowly confined to the low-latitude stratosphere, it can influence weather and climate worldwide through its effects on prominent modes of climate variability such as the North Atlantic Oscillation. While the theory of wave momentum transport is well established, uncertainties remain as to the relative importance of different wave types in driving the QBO, and current weather and climate models have difficulty in simulating it.This project seeks to improve understanding of waves in the TTL by building and launching a balloon-borne instrument which receives positioning signals from satellites of the Global Navigation Satellite System (GNSS, which includes the GPS satellites launched by the US). The GNSS signals are refracted as they pass through the atmosphere, and the amount of refraction can be used to infer air temperature in the upper troposphere. Because the profiles are retrieved from the rising and setting, or occultation, of the GNSS satellites relative to the receiver, the balloon-borne instrument has the acronym ROC, for Radio OCcultation.ROC is developed for use on balloons flow as part of the Strateole-2 field campaign organized by the Centre National d'Etudes Spatiales (CNES), the French Space Agency, and the Laboratoire de Meteorologie Dynamic (LMD) of the University of Paris-Saclay. Strateole-2 is a five-year campaign, with a small validation deployment in 2018 and full science deployments in 2020-2021 and 2022-2023. Balloons are launched from the Seychelles (about 5S in the Indian Ocean), with the expectation that each balloon will circle the earth for up to 90 days and observe the TTL between 20S and 15N. This award supports US participation in the validation campaign and the first full science deployment, along with post-campaign analysis. It is one of three awards made to US PIs for participation in Strateole-2, the full set being AGS-1643022, AGS-1642277/1642246, and AGS-1642650/1653644. ROC is oriented to retrieve signals from GNSS satellites on either side of the balloon flight path, with observations taken between 8km and the flight level of about 20km and a vertical resolution between 200m and 250m. The observing geometry is such that observations at lower levels are farther away from the balloon, so that observations at 18, 15, and 12km altitude correspond to distances of roughly 100, 200, and 300km on either side of the balloon. The waves of interest have periods from hours to days and ROC can record two to three occultations per hour. Thus the three-dimensional structure of the waves is captured by the ROC measurements as the balloon advances along its trajectory.ROC is accompanied by two other instruments which provide complementary observations. One is the Balloonborne Cloud Overshoot Observation Lidar (BeCOOL), provided by the Laboratoire Atmospheres, Milieux, Observations Spatiales (LATMOS, a laboratory of the Institut Pierre Simon Laplace) in collaboration with CNES. The lidar provides measurements of cirrus clouds which can be combined with ROC observations to examine the role of wave motions in generating cirrus clouds. The other is the Temperature SENsor (TSEN), an instrument from LMD which records atmospheric temperature and pressure at the gondola. Gondola displacements are precisely determined by ROC, and TSEN observations are used to factor out gondola movement relative to the ambient wave motion (these are super-pressure balloons which fly at a level of constant density). The displacement data are then used to estimate the wave momentum flux at flight level associated with the large-scale waves observed by ROC.The work has scientific broader impacts due to the value of the observations for addressing a variety of questions regarding the effect of wave motions on TTL clouds, stratospheric humidity, and the QBO. Observations collected in this project will be made available to the research community from servers at the Laboratory for Atmospheric and Space Physics at the University of Colorado so that they can be freely examined by the research community. The project also engages undergraduate students through a research class, offered simultaneously at the University of California San Diego, the University of Arizona (UA), and the Autonomous University of Mexico (UNAM), in which students design a research project based on a test flight of ROC. The class is followed by undergraduate research internships at UCSD, UA, the Research Experiences in Solid Earth Sciences for Students (RESESS) program at UNAVCO (the University NAVSTAR Consortium, dedicated to applying GNSS technology to earth science), and the Significant Opportunities in Atmospheric Research and Science (SOARS) program of the University Corporation for Atmospheric Research. Beyond these broader impacts, the project supports two graduate students.

热带对流层上层和平流层下层是各种波动的所在地，这些波动在天气、气候和大气环流中发挥着关键作用。 由大面积热带对流产生的宽波（水平波长跨越几度纬度）但浅波（垂直波长约一到四公里）是本次调查的主题。 这些波之所以引起人们的兴趣，有以下三个原因：首先，这些波可以诱发热带对流层顶层 (TTL) 中卷云的形成，TTL 是对流层和平流层之间的过渡区，长度从约 14 公里延伸到 18.5 公里。 当与波浪相关的上升空气运动降低气温并导致水蒸气以卷云冰晶形式冻结时，就会形成 TTL 卷云。 由此产生的云可能太薄，无法从地面或卫星上看到，但它们具有重要的气候影响，因为它们捕获传出的红外辐射，从而使大气变暖。 这种云的普遍程度很难量化，并且与由于冰粒从深积云中流出而形成的卷云相比，波动作为 TTL 卷云来源的相对重要性尚不清楚。波浪引起的温度降低产生的水蒸气可能是进入平流层的水蒸气量的重要限制。 TTL有时被称为“平流层的门户”，因为全球平流层中的大部分水蒸气都是通过TTL进入的。 与对流层相比，平流层极其干燥，但平流层水蒸气仍然很重要，因为它具有相对较强的温室效应，可以导致极地平流层云的形成，而极地平流层云是臭氧空洞形成的关键。可以将动量从对流层传输到平流层，而波动量传输是平流层准两年期振荡（QBO）的主要驱动力，该振荡是东风与平流层之间的交替全球热带地区出现的西风，周期超过两年。虽然 QBO 狭隘地局限于低纬度平流层，但它可以通过影响北大西洋涛动等气候变率的主要模式来影响全世界的天气和气候。 虽然波浪动量传输理论已经很成熟，但不同波浪类型在驱动 QBO 中的相对重要性仍然存在不确定性，并且当前的天气和气候模型难以对其进行模拟。该项目旨在增进对 TTL 中波浪的理解建造并发射气球载仪器，接收来自全球导航卫星系统（GNSS，包括美国发射的 GPS 卫星）卫星的定位信号。 GNSS 信号在穿过大气层时会发生折射，折射量可用于推断对流层上层的气温。 由于剖面是从 GNSS 卫星相对于接收器的升起和落下或掩星中检索到的，因此气球载仪器的缩写为 ROC，即无线电掩星。ROC 是为用于气球流而开发的，作为 Strateole 的一部分-2 由法国国家空间研究中心 (CNES)、法国航天局和法国大学气象动力学实验室 (LMD) 组织的实地活动巴黎-萨克雷。 Strateole-2 是一项为期五年的活动，于 2018 年进行小型验证部署，并于 2020-2021 年和 2022-2023 年进行全面科学部署。气球从塞舌尔群岛（在印度洋大约 5 秒）发射，预计每个气球将绕地球飞行长达 90 天，并观察 20 秒至 15 秒之间的 TTL。该奖项支持美国参与验证活动和首次全面科学部署以及活动后分析。这是美国 PI 因参与 Strateole-2 而获得的三个奖项之一，全套奖项分别是 AGS-1643022、AGS-1642277/1642246 和 AGS-1642650/1653644。 ROC 旨在检索气球飞行路径两侧 GNSS 卫星的信号，在 8 公里到飞行高度约 20 公里之间进行观测，垂直分辨率在 200 m 到 250 m 之间。观测几何结构使得较低高度的观测距离气球较远，因此 18、15 和 12 公里高度的观测对应于气球两侧大约 100、200 和 300 公里的距离。 感兴趣的波的周期从几小时到几天不等，ROC 每小时可以记录两到三次掩星。 因此，当气球沿着其轨迹前进时，ROC 测量可以捕获波浪的三维结构。ROC 配有另外两种仪器，可提供互补的观测。 其中之一是气球云超调观测激光雷达 (BeCOOL)，由大气、Milieux、空间观测实验室（LATMOS，皮埃尔·西蒙·拉普拉斯研究所的一个实验室）与 CNES 合作提供。 激光雷达提供卷云测量，可以与 ROC 观测相结合，以检查波动在生成卷云中的作用。 另一个是温度传感器 (TSEN)，这是 LMD 的一款仪器，用于记录吊舱内的大气温度和压力。 吊舱位移由 ROC 精确确定，TSEN 观测结果用于分解吊舱相对于环境波浪运动的运动（这些是以恒定密度飞行的超压气球）。 然后使用位移数据来估计与 ROC 观测到的大规模波浪相关的飞行高度的波浪动量通量。由于观测对于解决有关波浪影响的各种问题的价值，这项工作具有更广泛的科学影响TTL 云、平流层湿度和 QBO 上的运动。 该项目收集的观测结果将通过科罗拉多大学大气和空间物理实验室的服务器提供给研究界，以便研究界可以自由检查。该项目还通过加州大学圣地亚哥分校、亚利桑那大学 (UA) 和墨西哥自治大学 (UNAM) 同时开设的研究课程吸引本科生参与，学生根据测试设计一个研究项目中华民国的飞行。 该课程之后是 UCSD、UA 的本科生研究实习、UNAVCO（大学 NAVSTAR 联盟，致力于将 GNSS 技术应用于地球科学）的学生固体地球科学研究经验 (RESESS) 计划，以及大气领域的重大机会大学大气研究公司的研究与科学（SOARS）计划。除了这些更广泛的影响之外，该项目还支持两名研究生。

项目成果

First Super‐Pressure Balloon‐Borne Fine‐Vertical‐Scale Profiles in the Upper TTL: Impacts of Atmospheric Waves on Cirrus Clouds and the QBO

第一个超压气球 - TTL 上部的精细 - 垂直 - 尺度剖面：大气波对卷云和 QBO 的影响

• DOI: 10.1029/2021gl097596
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Bramberger, Martina;Alexander, M. Joan;Davis, Sean;Podglajen, Aurelien;Hertzog, Albert;Kalnajs, Lars;Deshler, Terry;Goetz, J. Douglas;Khaykin, Sergey
• 通讯作者: Khaykin, Sergey

Balloon‐Borne Observations of Short Vertical Wavelength Gravity Waves and Interaction With QBO Winds

• DOI: 10.1029/2020jd032779
• 发表时间: 2020-08
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: R. Vincent;M. Alexander

Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign

• DOI: 10.5194/acp-22-15379-2022
• 发表时间: 2022-12
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: B. Cao;J. Haase;M. Murphy;M. Alexander;M. Bramberger;A. Hertzog

Around the World in 84 Days

• DOI: 10.1029/2018eo091907
• 发表时间: 2018-03
• 期刊: Eos
• 作者: J. Haase;M. Alexander;A. Hertzog;L. Kalnajs;T. Deshler;S. Davis;R. Plougonven;P. Cocquerez;Stéphanie Venel

Tropical Wave Observations From the Reel‐Down Atmospheric Temperature Sensor (RATS) in the Lowermost Stratosphere During Strateole‐2

平流层最低层 ReelDown 大气温度传感器 (RATS) 的热带波观测 —2

• DOI: 10.1029/2023gl104711
• 发表时间: 2023
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Bramberger, Martina;Goetz, Doug;Alexander, M. Joan;Kalnajs, Lars;Hertzog, Albert;Podglajen, Aurelien
• 通讯作者: Podglajen, Aurelien