Collaborative Research: Laboratory and Ground-Based Studies Addressing Unresolved Aspects of Atmospheric Ice Nucleation

合作研究：实验室和地面研究解决大气冰核形成的未解决问题

• 批准号: 0841602
• 负责人: Paul DeMott
• 金额: $ 78.24万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0841602&HistoricalAwards=false
• 关键词: Collaborative; Research; Laboratory; Ground; Based

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project focuses on advancing understanding of critical issues in atmospheric ice nucleation, one of the most basic processes affecting precipitation and impacting the radiative properties of cold clouds. Incomplete understanding of ice initiation processes in clouds results in large uncertainties in the ability to model clouds and precipitation. Under prior support, the Principal Investigators (PIs) have made advancements in the area of real-time measurement of heterogeneous ice nuclei (IN) and in understanding the role of different aerosol particle types capable of initiating ice formation in the atmosphere. These measurements highlight significant remaining questions. For example, atmospheric studies have emphasized the importance of mineral dust as a significant IN source, but laboratory studies of natural dust particles up to 1 micron in size have shown no evidence for IN activity warmer than about -15 degrees Celsius. The second most prevalent IN composition that has been identified in the atmosphere are carbonaceous particles, but their sources are unresolved. Biological aerosols represent potential sources for primarily carbonaceous IN, but their number concentrations are poorly observed by existing measurement methods. Finally, apparent degradation of IN efficiency in polluted air has been observed but there is little fundamental basis for understanding the impacts of atmospheric processing on IN activation. The Principal Investigators will use laboratory studies to investigate ice formation by natural dusts at sizes up to 5 microns to quantify the relation between IN activation temperature and mineral dust particle size for different mineralogical types. They also will quantify the changes in IN activation properties after exposure to realistic degrees of atmospheric processing. Examinations of supermicron-sized particles as ice nuclei in the PIs' continuous flow ice nuclei instrument is made possible by application of a new particle phase-discrimination detector (PPD) that identifies ice crystals and aerosol particles by their spatial scattering patterns rather than optical size alone. Use of the PPD will permit exploration of the impact of evaporation of IN containing droplets on ice nucleation, of interest due to inferences that this process spawns primary or secondary ice nucleation. The PIs will investigate the number concentrations of biological ice nuclei through studies that utilize a real-time IN detector and application of real-time mass spectrometric or post-application of microbiological methods (DNA analyses) on activated and collected IN. Using this approach, IN-active bacteria are identified at specific temperature and humidity conditions, enabling an assessment of their role across the full temperature regime of tropospheric clouds. After refining procedures through laboratory studies, The PIs will apply these methods to quantify the proportion of ambient IN, as a function of temperature, that are of biological origin. The opportunity also exists to identify heretofore unrecognized biological IN. The intellectual merit of the project lies in the opportunity to confirm and augment present understanding and quantification of ice initiation in clouds and its relation to the specific properties of key atmospheric source populations of ice nuclei. The PIs will quantify ice formation by IN across their atmospherically-relevant size and temperature range, apply advanced techniques for detecting IN composition, determine the impacts of atmospheric processing on IN activation, and explore ice formation mechanisms. Nucleation parameterization development for numerical modeling studies may be advanced using results from this research. This work will have broader impacts through promoting graduate education and training, enhancing research infrastructure, development and testing of new instrumentation and methods, application of results toward global climate change issues through associated numerical modeling studies, and fostering cross-disciplinary research between the atmospheric and biological sciences. The PIs will encourage application of results through related modeling studies, collaboration with other researchers, and participation in working groups. Graduate students and a postdoctoral scientist will participate and the work will involve collaborations across multiple disciplines and universities. Results will be disseminated via a project web site, publications, and participation in conferences. Finally, these data are of critical importance to unresolved impact of aerosols on ice clouds and global climate.

该奖项是根据2009年的《美国回收与再投资法》（公法111-5）资助的。本项目着重于促进对大气冰核中关键问题的理解，这是影响降水和影响寒冷云的辐射特性的最基本的过程之一。对云中冰开始过程的不完全了解导致建模云和降水的能力大大不确定性。 在先前的支持下，主要研究人员（PIS）在实时测量异质冰核（IN）的实时测量领域以及了解能够在大气中启动冰形成的不同气溶胶颗粒类型的作用方面取得了进步。这些测量突出了剩余的重大问题。 例如，大气研究强调了矿物灰尘在来源中的重要性，但是对高达1微米的天然灰尘颗粒的实验室研究没有显示出比摄入量的证据，而不是摄氏-15摄氏度。在大气中发现的第二个最普遍的成分是碳质颗粒，但它们的来源尚未解决。 生物气溶胶代表了主要碳质的潜在来源，但是通过现有测量方法观察到它们的数量浓度很差。 最后，已经观察到污染空气中效率的明显降解，但是了解大气加工对激活中的影响几乎没有基本基础。首席研究人员将使用实验室研究研究最多5微米的天然灰尘形成冰块，以量化不同矿物类型类型的激活温度与矿物粉尘粒径之间的关系。 他们还将在暴露于现实的大气加工程度后量化激活特性的变化。 通过应用新的粒子相歧化探测器（PPD），通过使用新的粒子相差异探测器（PPD）来检查超微米尺寸的颗粒作为PIS连续流冰核仪器中的冰核的检查，通过其空间散射模式而不是单独的光学大小来识别冰晶和气溶胶颗粒。 PPD的使用将允许探索含液滴对冰核的蒸发的影响，这是由于推断该过程产生了原发性或次级冰核的推断。 PI将通过在探测器中使用实时的研究并应用微生物方法的实时质谱或应用后的实时质谱法（DNA分析）来研究生物冰核的数量浓度。 使用这种方法，在特定的温度和湿度条件下确定了活性细菌，从而评估其在对流层云的全温度状态下的作用。 在通过实验室研究完善程序之后，PI将应用这些方法来量化环境的比例，作为温度的函数，具有生物学来源。也存在机会识别未识别的生物学。该项目的智力优点在于有机会确认和增强对云中冰开始的当前理解和量化及其与关键大气源冰核的特定特性的关系。 PI将通过其在大气中与温度相关的大小和温度范围内量化冰的形成，应用高级技术以在组成中检测，确定大气加工对激活的影响，并探索冰形成机制。 使用这项研究的结果，可以进行数值建模研究的成核参数化开发。这项工作将通过促进研究生教育和培训，增强研究基础设施，开发和测试新仪器和方法，通过相关的数值建模研究将结果应用于全球气候变化问题以及促进大气和生物学科学之间的跨学科研究，从而产生更广泛的影响。 PI将通过相关的建模研究，与其他研究人员的合作以及参与工作组来鼓励应用结果。 研究生和博士后科学家将参加，这项工作将涉及多个学科和大学之间的合作。结果将通过项目网站，出版物和会议参与来传播。最后，这些数据对于气溶胶对冰云和全球气候的未解决影响至关重要。