Collaborative Research: Field Measurements of Clouds and Aerosol Particles over the Southern Ocean in SOCRATES

合作研究：苏格拉底对南大洋上空云和气溶胶颗粒的现场测量

• 批准号: 1660509
• 负责人: Lynn Russell
• 金额: $ 18.8万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 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: 2017-03-01 至 2021-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1660509&HistoricalAwards=false
• 关键词: Collaborative; Research; Field; Measurements; Clouds

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.The work funded under this award 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.A key issue to be addressed in the campaign is the relative abundance of supercooled liquid water (SLW) droplets and ice particles in SO clouds, as SLW is more prevalent in SO clouds than their Northern Hemisphere counterparts. The PIs hypothesize that the extent to which SLW cloud droplets freeze into ice particles is more strongly modulated in SO clouds by the vigor of cloud updrafts than by the availability of Ice nucleating particles (INPs, particles within liquid droplets which trigger freezing). The PIs also seek to determine the relative influence of overlying free tropospheric aerosol concentrations versus local surface and boundary layer controls, including precipitation and wind speed, in determining the concentration of liquid droplets in boundary layer clouds.Work funded under this award contributes to SOCRATES by measuring aerosol and cloud hydrometeor properties, specifically addressing three questions (from the proposal summary):1) What are the chemical and physical properties of sub-micron and coarse-mode aerosol particles in the region, and how do they relate to cloud condensation nuclei (CCN, particles around which cloud droplets form), INP, and cloud properties?2) What fraction of SO condensed water remains supercooled as a function of temperature, and can this be related to a dearth of INPs?3) What is the role of biological aerosol particles in cloud formation over the SO?These questions are addressed through in-situ air sampling using inlets available on the GV. Sampling of cloudy air uses a specialized inlet known as a counterflow virtual impactor (CVI), which separates cloud droplets and ice crystals from smaller aerosol particles and other non-cloud material. Droplets and ice crystals are heated in the CVI to evaporate their water substance and the resulting vapor is measured with a laser hygrometer to determine total condensed water content. Once the water is evaporated the droplets and ice are reduced to their nucleating particles (referred to as residual particles), which are counted and sized using an aerosol spectrometer. A fluorescence-based spectrometer is used to separately count and size biological particles so that their role in nucleation can be assessed. Residual particles are collected on slides for laboratory analysis using electron and X-ray microscopy that can determine morphology, composition, and mixing state. A key question in the analysis is the hygroscopicity of the particles, meaning their ability to absorb water vapor and thus serve as CCN. Additional measurements from wing-mounted supercooled liquid probes are used to estimate the ratio of SLW to ice content in the clouds.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. A further contribution to basic research is the development of a clean-in-place system for the CVI inlet, which will improve the reliability of the CVI for future users, particular in salty marine environments. Campaign outreach to K-12 students and the general public is conducted through regular newsletters and blogs, and an interactive "Ask SOCRATES" website. Events in which campaign videos, microscope images of cloud particles, and aerosol samples collected during the campaign are presented to the general public, are also planned. This award provides support and training to a graduate student and funds the participation of a second student in the campaign, thereby contribution to the development of the future workforce in this research area.

南大洋（SO），意思是高纬度南半球的全球海洋，作为地球上风暴最多的地方，它有着当之无愧的声誉。SO的偏远及其恶劣的条件严重限制了对其上方发生的大气过程的观测，包括沿南极锋移动的气旋中的云过程。然而，由于各种原因，这些过程引起了人们的兴趣，其中包括SO云相对不受大陆和人为气溶胶的影响，因此该地区是研究原始条件下云行为的天然实验室。SO云还通过将射入的阳光反射回太空，在地球的能量平衡中起着重要的冷却作用。有证据表明，这种冷却对与热带辐合带相关的低纬度降雨分布具有长期影响，并且由于全球气候变化导致的SO云量变化将影响南半球急流的位置和强度。我们对SO云过程缺乏了解的一个指标是在气候模式模拟中发现的SO云覆盖不足，这伴随着海洋表面对阳光的过度吸收，这反过来可能导致对气候敏感性估计的误差。模拟云量的不足在沿SO风暴路径行进的锋面天气系统冷、干扇区的边界层和对流层下层云（顶部低于3km）中最为明显。这项由该奖项资助的工作是名为“南大洋云、辐射、气溶胶、运输实验研究”（SOCRATES）的大型野外活动的一部分。该活动的主要活动是部署一架湾流V （GV）研究飞机，由美国国家大气研究中心地球观测实验室维护。GV将以澳大利亚霍巴特为基地，进行多次飞越南极锋的飞行，收集SO云及其发生的气象条件的数据。GV配备了用于记录环境气象条件的落差探空仪，用于观测云层的雷达和激光雷达，以及安装在机翼上或位于入口后面的仪器，用于对气溶胶和云颗粒（液滴和冰晶）进行取样、收集和分析。苏格拉底活动是对国际和其他美国机构计划的SO活动的补充，包括在船上和在南纬54度的一个无人居住的小岛麦夸里岛进行的水面观测。运动中需要解决的一个关键问题是SO云中相对丰富的过冷液态水（SLW）液滴和冰粒，因为SLW在SO云中比北半球的同类云更普遍。PIs假设，在SO云中，SLW云滴冻结成冰粒的程度更强烈地受到云上升气流的活力的调节，而不是受到冰核粒子（INPs，液滴内触发冻结的粒子）的调节。在确定边界层云中液滴的浓度时，指数还试图确定上覆自由对流层气溶胶浓度与当地地表和边界层控制因素（包括降水和风速）的相对影响。该奖项资助的工作通过测量气溶胶和云的水成物特性为SOCRATES做出贡献，具体解决三个问题（来自提案摘要）：1)该地区亚微米和粗模气溶胶颗粒的化学和物理特性是什么，它们与云凝结核（CCN，云滴形成的颗粒）、INP和云特性有何关系？2)作为温度的函数，有多少比例的SO冷凝水保持过冷状态，这是否与inp的缺乏有关？3)生物气溶胶粒子在SO上空云层形成中的作用是什么？这些问题都是通过使用GV上的入口进行现场空气采样来解决的。多云空气的采样使用一种称为逆流虚拟冲击器（CVI）的专用入口，它将云滴和冰晶与较小的气溶胶颗粒和其他非云物质分离开来。液滴和冰晶在CVI中加热以蒸发其水物质，并用激光湿度计测量产生的蒸汽以确定总冷凝水含量。一旦水被蒸发，液滴和冰就会被还原成成核粒子（称为残余粒子），这些粒子可以用气溶胶光谱仪来计数和确定大小。基于荧光的光谱仪用于单独计数和大小的生物颗粒，以便评估它们在成核中的作用。残余颗粒收集在载玻片上进行实验室分析，使用电子和x射线显微镜可以确定形态，成分和混合状态。分析中的一个关键问题是颗粒的吸湿性，这意味着它们吸收水蒸气的能力，从而起到CCN的作用。安装在机翼上的过冷液体探测器的额外测量用于估计云中SLW与冰含量的比例。由于SO云在确定全球气候对来自温室气体增加和其他因素的外部强迫的敏感性方面具有潜在的重要作用，因此这项工作具有更广泛的影响。该活动的数据将用于开发用于天气预报和气候影响评估的模型中更好的云表示。这些数据将提供给全世界的科学界，因此，通过为基础科学研究创造一个社区资源，该运动具有更广泛的影响。对基础研究的进一步贡献是开发CVI进气道的就地清洁系统，这将为未来用户提高CVI的可靠性，特别是在咸水海洋环境中。通过定期的时事通讯和博客，以及一个互动的“问苏格拉底”网站，向K-12学生和公众进行宣传活动。还计划举办活动，向公众展示活动视频、云粒子的显微镜图像和在活动期间收集的气溶胶样本。该奖项为一名研究生提供支持和培训，并资助第二名学生参与该活动，从而为该研究领域未来劳动力的发展做出贡献。

项目成果

Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate

云——气候变化中南大洋上空的成核粒子

• DOI: 10.1029/2020ef001673
• 发表时间: 2021
• 期刊: Earth's Future
• 作者: Twohy, Cynthia H.;DeMott, Paul J.;Russell, Lynn M.;Toohey, Darin W.;Rainwater, Bryan;Geiss, Roy;Sanchez, Kevin J.;Lewis, Savannah;Roberts, Gregory C.;Humphries, Ruhi S.
• 通讯作者: Humphries, Ruhi S.

Cloud Microphysical Effects of Aerosol Particle Sources and Marine Boundary Layer Processes

气溶胶颗粒源和海洋边界层过程的云微物理效应

• 发表时间: 2017
• 期刊: UC San Diego Electronic Theses and Dissertations
• 作者: Sanchez, Kevin J

Measured Constraints on Cloud Top Entrainment to Reduce Uncertainty of Nonprecipitating Stratocumulus Shortwave Radiative Forcing in the Southern Ocean

• DOI: 10.1029/2020gl090513
• 发表时间: 2020-11
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: K. Sanchez;Gregory Charles Roberts;M. Diao;L. Russell

Organic composition of three different size ranges of aerosol particles over the Southern Ocean

南大洋上空三种不同尺寸范围的气溶胶颗粒的有机成分

• DOI: 10.1080/02786826.2020.1845296
• 发表时间: 2021
• 期刊: Aerosol Science and Technology
• 影响因子: 5.2
• 作者: Saliba, G.;Sanchez, K. J.;Russell, L. M.;Twohy, C. H.;Roberts, G. C.;Lewis, S.;Dedrick, J.;McCluskey, C. S.;Moore, K.;DeMott, P. J.
• 通讯作者: DeMott, P. J.

Measurement report: Cloud processes and the transport of biological emissions affect southern ocean particle and cloud condensation nuclei concentrations

测量报告：云过程和生物排放物的传输影响南大洋颗粒和云凝结核浓度

• DOI: 10.5194/acp-21-3427-2021
• 发表时间: 2021
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: Sanchez, Kevin J.;Roberts, Gregory C.;Saliba, Georges;Russell, Lynn M.;Twohy, Cynthia;Reeves, Michael J.;Humphries, Ruhi S.;Keywood, Melita D.;Ward, Jason P.;McRobert, Ian M.
• 通讯作者: McRobert, Ian M.