Laboratory and Surface-based Studies of Atmospherically-relevant Ice Nucleating Particle Sources, Concentrations and Compositions

在大气颗粒上形成冰是一个基本过程，它可以通过水文循环、通过影响降水的效率和分布以及通过影响含冰云对太阳辐射和热辐射的散射来影响气候。由于对不断变化的自然和人类影响的粒子排放对云中结冰过程的作用认识不完全，限制当前和预估气候影响程度的努力存在很大的不确定性。该项目将确定从土壤和植物表面向大气排放的冰成核颗粒，特别是量化有机颗粒的贡献和性质，在这一组中，生物颗粒，与已知的全球无机冰成核颗粒来源，特别是沙漠矿物粉尘颗粒进行比较。结果将适用于在云、区域、天气预报和气候尺度上的数值模拟研究中改进冰成核过程的量化。该项目结合了大气和生物测量工具，以确定收集的土壤和植物样本中特定冰核颗粒类型的地表排放，并在直接大气采样期间识别它们的影响。将进行实验室研究，通过收集土壤颗粒和受区域重要生态系统的风吹拂的植物有机体进行冰核。研究将特别关注美国西部和中部平原地区的山间土壤、植物和生态类型，在这些地区，气溶胶云的相互作用可能影响水资源和严重风暴特征，但方法和结果将为未来其他地区的陆基和空中研究提供信息。将使用多种方法来测量颗粒在不同温度下进入液滴时冻结的数量，就像它们在自然云中一样，这些结果将与气溶胶的总质量和表面积有关。将应用专门的工具来表征颗粒冷冻的组成，包括电子探针分析，单颗粒质谱，选择性去除生物和有机颗粒的热化学处理，所有生物颗粒的基因扩增和测序，已知细菌和真菌冰核颗粒的特定基因定量，以及荧光生物颗粒的在线测量。这些相同的工具将被应用于检测收集区植物和土壤表面大气中每体积空气中不同冰核颗粒类型的存在和丰度，这些空气在受到风、雨和收获的扰动之前、期间和之后。将从这些结果发展出对冰成核的详细和概括的描述，以便应用于大气模式。这项工作的广泛影响包括促进博士后教育和培训，新仪器和方法的开发和测试，通过合作数值模拟研究将结果应用于气候变化问题，以及促进大气科学和生物科学之间的跨学科研究。这些结果对于气溶胶对冰云以及区域和全球气候的未解决影响至关重要。结果的传播将通过项目网站、出版物、参加会议和科学工作组以及与科学新闻机构的公开交流进行。

The formation of ice on atmospheric particles is a basic process that can impact climate through both the hydrological cycle, via influencing the efficiency and distribution of precipitation, and through impacts on the scattering of solar and thermal radiation by ice-containing clouds. Incomplete understanding of the role of changing natural and human-influenced particle emissions on ice formation processes in clouds results in large uncertainties in efforts to constrain the magnitude of current and projected climate impacts. This project will define the emissions of ice nucleating particles from soil and plant surfaces to the atmosphere, particularly to quantify the contributions and nature of organic particles, and within this group, biological particles, in comparison to known inorganic global ice nucleating particle sources, notably desert mineral dust particles. Results will be applicable toward improved quantification of ice nucleation processes in numerical modeling studies at cloud, regional, weather forecast, and climate scales.The project combines atmospheric and biological measurement tools toward defining the surface emissions of specific ice nucleating particle types from collected soil and plant samples, and toward recognition of their influence during direct atmospheric sampling. Laboratory studies will be performed of ice nucleation by collected soil particles and plant organisms subject to lofting by winds from regionally important ecosystems. Studies will have specific focus on soils, plants, and ecotypes of the intermountain West and Central U.S. Plains regions where aerosol cloud interactions may impact both water resources and severe storm characteristics, but methods and results will inform future land-based and airborne studies in other regions. Multiple methods will be used to measure the numbers of particles that freeze when they enter liquid drops at different temperatures, as they do in natural clouds, and these results will be related to total aerosol mass and surface area. Specialized tools will be applied to characterize the compositions of particles freezing, including electron microprobe analysis, single particle mass spectrometry, thermal and chemical treatments for selective removal of biological and organic particles, genetic amplification and sequencing of all biological particles, specific quantification of genes of known bacterial and fungal ice nucleating particles, and online measurements of fluorescent biological particles. These same tools will be applied toward detecting the presence and abundance of different ice nucleating particle types per volume of air in the atmosphere over plant and soil surfaces in collection areas before, during and after perturbations by wind, rain, and harvesting. Detailed and generalized descriptions of ice nucleation will be developed from these results for application in atmospheric models.The broader impacts of this work involve promoting postdoctoral education and training, development and testing of new instrumentation and methods, application of results toward climate change issues through collaborative numerical modeling studies, and fostering cross-disciplinary research between the atmospheric and biological sciences. Results are of critical importance to unresolved impact of aerosols on ice clouds and regional and global climate. Dissemination of results will occur via a project web site, publications, participation in conferences and scientific working groups and open communication with science news agencies.