Ice Nuclei and Ice Formation Processes in Tropical Cumulus Clouds

这一奖项将为研究人员提供机会，以提高我们对大气冰核(IN)的来源、物理和化学性质以及数量密度的了解。要阐明初级和次级冰形成过程在确定积云微物理成分和降水形成方面的作用，必须进行测量和建模。本研究的主要内容是参与冰在云中的实验-热带场战役(ICE-T)。ICE-T的重点是通过获取将在2011年6月至7月期间由NSF/NCAR C-130飞机收集的测量数据，更好地了解初级和次级冰生产在形成高耸的积云方面的作用。研究飞行的基地将设在美属维尔京群岛的圣克罗伊，目标数据收集区域为热带西部大西洋和邻近的加勒比海。该奖项支持的工作将提供使用科罗拉多州立大学连续流动扩散室(CFDC)仪器的IN测量，这是一种采用轴向温度梯度的环形流动扩散室，用于实时测量冰核。具体目标是在C-130上进行空中测量，以限制通过正在研究的云层内的初级冰核作用而可用于启动冰的气溶胶的浓度，并确定在温度高于零下20摄氏度时，尘埃与相关或不相关的生物气溶胶对冰形成的贡献。然后，这些研究人员将与ICE-T科学团队的其他成员合作，结合VIA观测数据和详细的数值模拟分析云内冰的形成过程。这一支持还将使研究小组继续努力推进对IN进行大气测量的技术，包括ICE-T的专门实施和参与拟议的航空科学仪器开发和教育项目。该奖项的智力价值在于预期在理解热带积云(热带积云在近赤道纬度普遍存在)方面的改善，以及确定不同类别的天然冰核(惰性和生物)在触发此类云中初始冰形成(并最终形成降水)中的作用。这项研究的更广泛影响将包括博士后科学家培训，与其他机构和学科的科学家合作，以及加强美国的研究基础设施。所获得的结果将对解决诸如气溶胶-云-气候相互作用和热带风暴形成等问题具有重要意义。此外，还计划在ICE-T实地活动期间开展一些公共宣传和教育活动。

This award will provide researchers the opportunity to improve our understanding of the sources, physical and chemical nature, and number concentrations of atmospheric ice nuclei (IN). The measurements and modeling involved to be conducted are important in order to elucidate the roles of primary and secondary ice formation processes in determining microphysical composition and precipitation formation in cumulus clouds. The main aspect of this study is participation in the Ice in Clouds Experiment - Tropical Field Campaign (ICE-T). ICE-T is focused on improved understanding of the role of primary and secondary ice production in developing towering cumulus clouds through access to measurements to be collected during June-July 2011 by the NSF/NCAR C-130 aircraft. Research flights will be based out of St. Croix, in the U.S. Virgin Islands, with a target data collection region over the Western Tropical Atlantic and adjacent Caribbean Sea. Work supported under this award will provide IN measurements using the Colorado State University continuous flow diffusion chamber (CFDC) instrument, which is a annular flow diffusion chamber employing axial thermal gradients for real time ice nuclei measurements. The specific objectives are to perform airborne measurements aboard the C-130 to constrain the concentration of aerosols available to initiate ice by primary ice nucleation processes within the clouds being investigated, and to determine contributions of dust versus associated or unassociated biological aerosol toward ice formation at temperatures warmer than -20 degC. These investigators will then collaborate with other members of the ICE-T science team to analyze in-cloud ice formation processes a combination of via observational data and detailed numerical simulations. This support will also allow the investigative team to continue efforts to advance the technology for making atmospheric measurements of IN, including specialized implementations for ICE-T and participation in the proposed Instrument Development and Education in Airborne Sciences project.The intellectual merit of the award rests in expected improvements in understanding ice formation processes tropical cumuli, which are ubiquitous at near-equatorial latitudes, and in defining the role of different classes (inert vs. biological) of natural ice nuclei in triggering the initial formation of ice (and ultimately, precipitation) in such clouds.The broader impact of the research will include postdoctoral scientist training, collaborations with scientists in other institutions and disciplines, and enhancing U.S. research infrastructure. The obtained will be important for addressing such topics as aerosol-cloud-climate interactions and tropical storm formation. Additionally, a number of public outreach and educational activities are planned during the ICE-T field campaign.