Ice Nuclei and Ice Formation Processes in Tropical Cumulus Clouds

该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浓度的理解。为了阐明初生冰和次生冰形成过程在确定积云微物理组成和降水形成过程中的作用，所进行的测量和模拟是很重要的。本研究的主要方面是参与云中冰实验-热带地区运动（Ice - t）。ice - t的重点是通过2011年6月至7月期间由NSF/NCAR C-130飞机收集的测量数据，提高对初级和次级冰产生在形成高塔积云中的作用的理解。研究飞行将以美属维尔京群岛的圣克罗伊岛为基地，目标数据收集区位于西热带大西洋和邻近的加勒比海。该奖项支持的工作将使用科罗拉多州立大学连续流扩散室（CFDC）仪器进行IN测量，CFDC是一种采用轴向热梯度的环形流扩散室，用于实时冰核测量。具体目标是在C-130上进行机载测量，以限制在被调查的云层内通过初级冰核过程引起冰的气溶胶浓度，并确定在温度高于-20摄氏度时，尘埃与相关或非相关生物气溶胶对冰形成的贡献。然后，这些研究人员将与ice - t科学小组的其他成员合作，通过观测数据和详细的数值模拟来分析云内冰的形成过程。这种支持还将使调查小组继续努力推进进行IN大气测量的技术，包括专门实施ICE-T和参与拟议的机载科学仪器开发和教育项目。该奖项的学术价值在于对热带积云形成过程的理解有望有所改善，热带积云在近赤道纬度地区普遍存在，并定义了不同类别的天然冰核（惰性与生物）在触发此类云中冰的初始形成（以及最终的降水）方面的作用。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。所获得的结果对于解决诸如气溶胶-云-气候相互作用和热带风暴形成等问题将是重要的。此外，在ICE-T实地运动期间还计划了一些公众宣传和教育活动。

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.