Effects of Aerosols on Microphysical Properties of Springtime Clouds Containing Ice

冰云在调节气候、产生降水和提供化学反应场所方面很重要。 在大气中，冰的成核主要有两种方式：通过溶液液滴的均质冻结和通过颗粒核的非均质相互作用。 均质冰成核可以通过理论进行预测，而非均质冰成核则要复杂得多。 有几种机制可以使异质冰核引发冰的形成，包括沉积、接触、浸没和冷凝。 在大气中各种条件下充当冰核的颗粒的类型和数量的特征非常差。 人为活动引起的颗粒物负荷的变化，无论是直接排放还是通过土地使用和降水变化，都可能影响冰和混合相云的特性。 然而，在我们了解冰形成的物理学之前，这些对冰云的“气溶胶间接影响”无法准确预测。先前的测量提供了一个开始，但需要更多的信息。 进一步理解冰成核需要结合现场实验，实验室研究和建模。 主要研究员将采用一种实验方法，包括直接撞击和蒸发冰晶，以评估其非挥发性核的特性。 这些信息将与其他研究人员的一系列补充测量结果相结合。 这项工作的主要目标是更好地了解冰在云中的冰层（ICE-L）实验中相对简单的云的冰成核。 将使用模型计算和现场测量研究与从飞机上取样冰有关的问题及其对收集的数据的潜在影响。 这将增加基本冰成核研究的知识价值。这项工作有几个方面对更广泛的社区很重要。 首先，了解由于人类活动（无论是直接还是间接通过土地利用变化）产生的气溶胶如何影响降水发展和云对地球气候的辐射影响至关重要。 第二，对人力资源产生积极影响。 计划为ICE-L实验提供一个强有力的教育部分，新技术允许将实时数据纳入大学气象学课程。 此外，一名本科生和一名研究生将与PI和同事一起分析和解释收集的数据。 此外，该项目将提高对飞机冰取样及其对过去和未来许多其他实验测量的影响的理解。

Ice clouds are important in regulating climate, in producing precipitation, and in providing sites for chemical reactions. Ice nucleation occurs in the atmosphere in two primary ways: through homogeneous freezing of liquid solution droplets and through heterogeneous interaction on a particulate nucleus. Homogeneous ice nucleation can be predicted by theory, while heterogeneous ice nucleation is much more complex. There are several mechanisms by which a heterogeneous ice nucleus may initiate ice formation, including deposition, contact, immersion, and condensation. The types and numbers of particles that act as ice nuclei under various conditions in the atmosphere are very poorly characterized. Changes to particulate loadings by anthropogenic activity, whether direct emissions or through land-use and precipitation changes, are likely to influence characteristics of ice and mixed-phase clouds. However, these "aerosol indirect effects" on ice clouds cannot be accurately predicted until we understand the physics of ice formation. Prior measurements provide a beginning, but much more information is needed. Further comprehension of ice nucleation will require a combination of field experiments, laboratory studies, and modeling. The Principal Investigator will undertake an experimental approach involving direct impaction and evaporation of ice crystals to evaluate the properties of their non-volatile nuclei. This information will be integrated with that from a series of complimentary measurements by other investigators. The primary objective in this work is to better understand ice nucleation in relatively simple clouds in the Ice in Clouds--Layer (ICE-L) experiment. Problems associated with sampling ice from aircraft, and their potential influence on collected data, will be studied using modeling calculations and field measurements. This will add to the intellectual merit of the basic ice nucleation studies. There are several aspects of this work that are important to the broader community. First, there is the primary importance of understanding how aerosol production due to human activity (whether directly or indirectly through land-use changes) influences precipitation development and the radiative impact of clouds on the earth's climate. Second, there is the positive impact on human resources. A strong educational component is planned for the ICE-L experiment, with new technology allowing real-time data to be integrated into university meteorology classes. Additionally, an undergraduate student and graduate students will work with the PI and colleagues to analyze and interpret the data collected. Additionally, this project will yield improved understanding of ice sampling by aircraft and its implications for past and future measurements in numerous other experiments.