Analysis of G-V Aircraft and Complementary SOCRATES Observations to Understand Clouds, Aerosols and their Interactions Over the Southern Ocean

分析 G-V 飞机和补充苏格拉底观测以了解南大洋上空的云、气溶胶及其相互作用

• 批准号: 1660609
• 负责人: Robert Wood
• 金额: $ 105.75万
• 依托单位: University of Washington
• 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: 2017-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1660609&HistoricalAwards=false
• 关键词: Analysis; Aircraft; Complementary; SOCRATES; Observations

The Southern Ocean (SO), meaning the global ocean of the high latitude Southern Hemisphere, has a well-deserved reputation as the stormiest place on earth. The remoteness of the SO and its unforgiving conditions have severely limited observations of atmospheric processes occurring above it, including cloud processes in the cyclones traveling along the South Polar front. Yet these processes are of interest for a variety of reasons, including the fact that SO clouds are relatively free from the effects of continental and anthropogenic aerosols, and the region is thus a natural laboratory for the study of cloud behavior under pristine conditions. SO clouds also play a significant cooling role in the energy balance of the planet by reflecting incoming sunlight back to space. There is evidence to suggest that this cooling has a long-range effect on the distribution of the low-latitude rainfall associated with the intertropical convergence zone, and that changes in SO cloudiness due to global climate change will affect the location and strength of the Southern Hemisphere jet stream. One indicator of our lack of understanding of SO cloud processes is the inadequate SO cloud cover found in climate model simulations, which is accompanied by excessive absorption of sunlight by the ocean surface which may in turn cause errors in estimates of climate sensitivity. The deficiency in simulated cloud cover is most pronounced in boundary layer and lower-tropospheric clouds (tops below 3km) in the cold, dry sectors of frontal weather systems traveling along the SO storm track.This project is part of a larger field campaign titled Southern Ocean Clouds, Radiation, Aerosol, Transport Experimental Study (SOCRATES). The primary activity of the campaign is the deployment of a Gulfstream V (GV) research aircraft maintained by the Earth Observing Laboratory of the National Center for Atmospheric Research. The GV will be based in Hobart, Australia and make multiple flights across the South Polar front collecting data on SO clouds and the meteorological conditions in which they occur. The GV is equipped with dropsondes to record ambient meteorological conditions, radar and lidar to observe the clouds, and instruments mounted on the wings or positioned behind inlets to to sample, collect and analyze aerosols and cloud particles (liquid droplets and ice crystals). The SOCRATES campaign is complementary to SO activities planned internationally and by other US agencies, including surface observations taken on ships and on MacQuarie Island, a small uninhabited island at 54 degrees South.Work supported under this award specifically addresses the relatively warm, shallow clouds found at the top of the atmospheric boundary layer, with a specific focus on cloud droplet number concentration, or the number of droplets per unit volume in a cloud. Droplet number concentration is a key parameter for understanding cloud properties and evolution, and in a pristine region like the SO it can be limited by the availability of cloud condensation nuclei (CCN), aerosol particles which absorb water vapor from the air to form droplets. The PIs seek to determine if droplet number concentration can be related to CCN concentration in the local boundary layer or the overlying free troposphere, or if droplet concentrations are more strongly influenced by turbulent cloud motions, removal through precipitation, or other meteorological factors. Previous studies suggest that low clouds in the colder air to the south of the South Polar front have higher mean droplet concentrations than the warmer clouds to the north, a difference which is not presently understood. Possible explanations include increased CCN production in the colder ocean waters to the south (meaning closer to the South Pole), and higher precipitation rates with increased CCN removal to the north.A variety of observations, collected in collaboration with other SOCRATES projects, are used to examine the controls on space and time variability of droplet number concentration in SO clouds:* size-resolved aerosol and CCN concentrations, both above and within the boundary layer, using probes and inlets on the GV at multiple flight levels;* precipitation rates, cloud updraft and downdraft strength, and cloud base and top heights determined from onboard radar and lidar.* near-surface aerosol and CCN concentrations from low-level flight legs, planned to sample as low as 150m above surface;* profiles of ambient temperature, moisture, and wind from dropsondes released from the aircraft.These data are combined to produce integrated datasets including a north-south "SOCRATES curtain" dataset which facilitates comparison with numerical model output. Modeling activities based on these datasets are also planned.The work has broader impacts due to the potentially significant role of SO clouds in determining the sensitivity of global climate to external forcing from greenhouse gas increases and other factors. Data from the campaign will be used to develop better representations of clouds in models used for weather prediction and climate impacts assessments. The data will be made available to the worldwide scientific community, thus the campaign has broader impacts by creating a community resource for basic science research. Outreach to K-12 students and the general public is conducted during the campaign through regular newsletters and blogs, and an interactive "Ask SOCRATES" website. This project provides support to two graduate students, thereby providing for the future workforce in this research area.

南大洋（So）意味着南半球高纬度的全球海洋，作为地球上最暴风雨的地方享有当之无愧的声誉。 SO及其不受欢​​迎的条件的远程性在其上方发生的大气过程严重有限，包括沿南极前沿行驶的旋风中的云过程。然而，这些过程是出于多种原因而引起的，包括这样的事实，即云相对不受大陆和人为气溶胶的影响，因此该地区是对原始条件下云行为进行研究的自然实验室。因此，云在地球的能量平衡中也发挥了重要的冷却作用，通过反射回到太空的阳光。有证据表明，这种冷却对与中热带收敛区相关的低纬度降雨的分布具有长期影响，并且由于全球气候变化而导致的云彩变化将影响南部的位置和强度半球喷气流。我们对SO云过程缺乏理解的一个指标是，在气候模型模拟中发现的云覆盖不足，这伴随着海面过度吸收阳光，这又可能导致气候灵敏度估计值的错误。 模拟云覆盖层的不足在边界层和低对流层云（低于3公里以下）中最明显海云，辐射，气溶胶，运输实验研究（苏格拉底）。该运动的主要活动是部署由国家大气研究中心的地球观察实验室维护的湾流V（GV）研究飞机。 GV将总部位于澳大利亚的霍巴特，并在南极前沿进行多次飞行，以收集有关云层和发生气象条件的数据。 GV配备了Dropsondes，可记录环境气象条件，雷达和激光雷达，以观察云，并安装在机翼上或放置在入口后面以进行样品，收集和分析气溶胶和云颗粒（液滴和冰晶体）。苏格拉底运动与计划在国际和其他美国机构计划进行的SO活动相辅相成，包括在船上和麦格理岛上进行的表面观察，这是南部54度的一个小型无人岛，该奖项由该奖项提供了支持，专门针对相对温暖，浅云，发现在大气边界层的顶部，特别关注云液滴数量浓度，或云中每单位体积的液滴数量。 液滴数量浓度是了解云特性和演变的关键参数，在像这样的原始区域中，它可以受到云凝结核（CCN）的可用性的限制，气溶胶颗粒会从空气中吸收水蒸气形成液滴。 PI寻求确定液滴数量浓度是否与局部边界层中的CCN浓度有关，或者上覆盖的自由对流层，或者液滴浓度是否受到湍流云运动的强烈影响，通过降水量去除或其他气象因素。先前的研究表明，南极前沿南部较冷的空气中的低云具有比北部温暖的云层更高的平均液滴浓度，这一差异目前尚不清楚。可能的解释包括增加了南部冷海水中的CCN产量增加（意味着更接近南极），以及更高的降水率，CCN去除到北部。与其他苏格拉底项目合作收集的各种观察结果，使用为了检查So云中液滴数量浓度的空间和时间变化的控制：*尺寸分辨的气溶胶和CCN浓度在边界层上和边界层内，使用GV上的探针和进气，在多个飞行水平上；*降水率，*云上升的强度和向下气流的强度，以及由板上雷达和激光雷达确定的云基底和顶部高度。*低水平飞行腿的近表面气溶胶和CCN浓度，计划在表面高达150m的情况下采样；*环境温度，环境温度的特征将水分和来自飞机释放的滴落的风能。这些数据合并以生产集成的数据集，包括南北“苏格拉底窗帘”数据集，以促进与数值模型输出的比较。 还计划了基于这些数据集的建模活动。由于SO云在确定全球气候对从温室气体增加和其他因素中的外部强迫的敏感性中的潜在重要作用而具有更大的影响。该活动的数据将用于在天气预测和气候影响评估的模型中开发更好的云表示。这些数据将提供给全球科学界，因此，通过为基础科学研究创造社区资源，该活动会产生更广泛的影响。在活动期间通过常规新闻通讯和博客以及互动的“ Ask Socrates”网站向K-12学生和公众推广。该项目为两名研究生提供了支持，从而为该研究领域的未来劳动力提供了支持。

项目成果

Evaluation of Cloud and Precipitation Simulations in CAM6 and AM4 Using Observations Over the Southern Ocean

使用南大洋观测评估 CAM6 和 AM4 中的云和降水模拟

• DOI: 10.1029/2020ea001241
• 发表时间: 2021
• 期刊: Earth and Space Science
• 影响因子: 3.1
• 作者: Zhou, Xiaoli;Atlas, Rachel;McCoy, Isabel L.;Bretherton, Christopher S.;Bardeen, Charles;Gettelman, Andrew;Lin, Pu;Ming, Yi
• 通讯作者: Ming, Yi

Evaluation of MODIS and Himawari‐8 Low Clouds Retrievals Over the Southern Ocean With In Situ Measurements From the SOCRATES Campaign

• DOI: 10.1029/2020ea001397
• 发表时间: 2021-01
• 期刊: Earth and Space Science
• 影响因子: 3.1
• 作者: Litai Kang;R. Marchand;W. Smith

The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

• DOI: 10.1073/pnas.1922502117
• 发表时间: 2020-07
• 期刊: Proceedings of the National Academy of Sciences of the United States of America
• 影响因子: 11.1
• 作者: I. McCoy;D. McCoy;R. Wood;L. Regayre;D. Watson‐Parris;D. Grosvenor;J. Mulcahy;Yongxiang Hu;F. Bender;P. Field;K. Carslaw;H. Gordon

How Well Do Large‐Eddy Simulations and Global Climate Models Represent Observed Boundary Layer Structures and Low Clouds Over the Summertime Southern Ocean?

大涡模拟和全球气候模型在多大程度上代表了夏季南大洋上空观测到的边界层结构和低云？

• DOI: 10.1029/2020ms002205
• 发表时间: 2020
• 期刊: Journal of Advances in Modeling Earth Systems
• 影响因子: 6.8
• 作者: Atlas, R. L.;Bretherton, C. S.;Blossey, P. N.;Gettelman, A.;Bardeen, C.;Lin, Pu;Ming, Yi
• 通讯作者: Ming, Yi

Wavelet Analysis of Properties of Marine Boundary Layer Mesoscale Cells Observed From AMSR‐E

• DOI: 10.1029/2021jd034666
• 发表时间: 2021-06
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Xiaoli Zhou;C. Bretherton;R. Eastman;I. McCoy;R. Wood