MRI: Development of a Water Vapor and Temperature Mapping System to Study Cloud-turbulence Interactions in the Michigan Technological University (MTU) Pi-Chamber

气溶胶和云层是调节地球辐射平衡和气候的最重要因素之一，它们以复杂的方式相互作用。气溶胶起着云核的作用，决定了云的形成和生命周期；反过来，云又转化和去除了大气中的气溶胶。湍流通过影响云滴的尺寸分布、气溶胶的成核、水化和活化以及空间分离，在这些过程中起着关键作用。例如，在云的边缘将干燥空气夹带到饱和空气中的混合是一个重要但仍未完全了解的过程，需要进一步的实验室和实地研究。由于湍流引起的小空间(100 Mm)和时间(10s)尺度的水汽和温度波动，理解和模拟气溶胶和云之间的复杂相互作用是具有挑战性的。需要开发新的分析工具，将这些精细结构过程与气候相关的云特性联系起来。由新仪器实现的研究将有助于理解气溶胶、云和湍流之间错综复杂的相互作用，因此将产生明显和关键的更广泛的影响，而不仅仅是简单的科学好奇心。该项目还将通过实践研究和指导活动促进研究生和本科生的职业发展，并有助于培养新一代乐器演奏家。为了帮助填补STEM的性别和少数族裔空白，该项目将与密歇根理工大学(MTU)的机构公平和包容性办公室合作，并通过密歇根学院/大学伙伴计划增加对代表不足群体的学生的接触。该开发项目的科学目标是设计、建造和测试一种新的仪器，用于在密歇根理工大学的湍流多相云室中研究湍流对云和气溶胶的影响。这一仪器将大大提高该实验室的能力，并使新的令人振奋的研究成为可能。密封舱是一个社区共享设施，可以产生受控的环境和对流湍流条件，并通过不同的模式(例如，通过膨胀或通过垂直温度梯度混合)形成云(暖、冷或混合)。在混合模式下，云可以维持几个小时/天，因此可以不受时间限制地详细研究微物理性质和气溶胶-云-湍流相互作用。为了了解湍流如何影响温度、水蒸气和液态水场，人们需要绘制它们的时空分布图。为了实现这一目标，该项目将开发一种分析工具，在不影响湍流条件的情况下对燃烧室内的温度和水(蒸汽和液体)分布进行成像，同时提供与感兴趣过程相关的空间和时间分辨率(~1-20厘米和~1 S)。远程成像系统基于拉曼散射，携带关于水浓度和温度的信息。该仪器将成为云室共享设施的组成部分，增强其科学和分析能力，并扩大国家和国际合作。新仪器的研究将包括：a)研究均匀和非均匀混合对云滴增长和尺寸分布的影响、相关的长度尺度以及湍流如何影响饱和比场。B)饱和比场的小尺度细节，它如何确定初始激活、云滴增长和尺寸分布演变，以及由饱和比起伏引起的液滴演变如何反馈到云湍流中。C)厘米级间歇对气溶胶空间分离、增湿、活化和液滴形成的影响。

Aerosols and clouds are among the most important factors regulating our planet's radiative balance and climate, while interacting in complex manners. Aerosols act as cloud nuclei, determining the formation and lifecycle of clouds; conversely, clouds transform and remove aerosols from the atmosphere.Turbulence plays a key role in these processes by influencing cloud droplet size distribution, aerosol nucleation, hydration and activation, and spatial segregation. For example, mixing by entrainment of dry air into saturated air at the edges of a cloud is an important and still not fully understood process that requires further laboratory and field studies. Understanding and modeling the complex interactions between aerosols and clouds is challenging due to turbulence-induced water vapor and temperature fluctuations at small spatial (100mm) and temporal (10s) scales. Novel analytical tools need to be developed to link these fine-structure processes to climate-relevant cloud properties.The research enabled by the new instrument will help understanding the intricacies of the interactions between aerosol, clouds and turbulence, and will thus have clear and critical broader impacts, beyond simple scientific curiosity. The project will also promote graduate and undergraduate students' career development through hands-on research and mentoring activities and contribute to growing the new generation of instrumentalists. To help filling gender and minorities gaps in STEM, the project will work with the office of institutional equity and inclusion at Michigan Technological University (MTU) and through the Michigan College/University Partnership Program to increase the outreach to students from under-represented groups.The scientific objective of this development project is to design, construct and test a new instrument for the study of the effects of turbulence on clouds and aerosols in the Michigan Technological University's turbulent multiphase cloud chamber. This instrument would significantly enhance the capability of the chamber and enable new exciting research. The chamber - a community shared facility - can generate controlled environmental and convective turbulent conditions, and form clouds (warm, cold or mixed) through different modes (e.g., by expansion or by mixing through a vertical temperature gradient). In the mixing mode, clouds can be maintained for several hours/days and therefore microphysical properties and aerosol-cloud-turbulence interactions can be studied in detail with no time constraints. To understand how turbulence shapes temperature, water vapor and liquid water fields, one needs to map their spatial and temporal distributions. To achieve this goal, the project will develop an analytical tool for imaging temperature and water (vapor and liquid) distributions inside the chamber without affecting the turbulent conditions, while providing spatial and temporal resolutions relevant to the processes of interest (~1-20 cm and ~1 s).The remote imaging system is based on Raman scattering that carries information on water concentrations and temperature. The instrument will become integral part of the cloud chamber shared facility enhancing it scientific and analytical capacity and expanding national and international collaborations. Research enabled by the new instrument will include: a) Study of the effect of homogeneous vs. inhomogeneous mixing on cloud droplet growth and size distribution, the relevant length scales and how turbulence influence the saturation ratio field. b) Small-scale details of the saturation ratio field, how it determines initial activation, cloud droplet growth and size distribution evolution, and how the droplet evolution caused by the saturation ratio fluctuations feedback into the cloud turbulence. c) Effect of centimeter-scale intermittencies on aerosol spatial segregation, humidification, activation and droplet formation.