Spectral Characterization of Atmospheric Dust from the IR to the UV: A Combined Laboratory and Modeling Study of Composition, Size, and Shape Effects on Dust Optical Properties

矿物粉尘气溶胶在大气中起着至关重要的作用。尘埃通过直接吸收和散射从红外（IR）到紫外线（UV）的光谱来影响地球的辐射平衡。大气尘埃颗粒也作为云成核的场所，间接影响反照率，并作为对流层反应的反应表面，改变重要气相物质（如SO2）的化学平衡。正确建模粉尘对天气、气候和空气质量的影响需要关于粉尘负荷和成分、大小和形状（CSS）分布的准确信息，以及对粉尘光学（散射和吸收）特性的适当处理。通过光学遥感可以获得粉尘负荷和CSS分布。然而，遥感尘埃检索也严重依赖于气溶胶光学特性的准确处理。因此，粉尘光学特性的不确定性可能导致估计粉尘负荷和CSS分布的误差，从而对天气和空气质量预报以及气候建模产生有害影响。知识价值。我们将通过实验室测量和建模分析来研究尘埃在红外-紫外光谱中的光学特性。这项研究将集中在真实的灰尘样本上。气溶胶消光和光散射特性将通过实时原位单颗粒飞行时间质谱法和颗粒大小以及各种非原位方法测量颗粒CSS分布来分析。由于粒子的CSS分布将与光学性质同时测量，因此可以在很少（或没有）可调参数的情况下与理论模拟进行详细比较。这项工作的主要目标是建立使用光谱和偏振测量来推断矿物粉尘气溶胶CSS分布的方法，并探索这些分布如何被大气老化所改变。本工作提供的定性见解和定量数据可以纳入遥感检索算法，提高气溶胶辐射传输模型用于沙尘检索和气候强迫计算的可靠性，从而改变我们对沙尘对大气化学、动力学和气候影响的认识。更广泛的影响。这些活动为博士后和学生提供了发展成为独立科学家的巨大机会。这项研究包括实验气溶胶科学、光散射、光谱学和反应动力学研究等方面，并结合了广泛的理论建模程序。学生参与工作的各个方面，在研讨会和会议上展示他们的成果。通过长期的合作，两位导师成功地指导了各级学生和博士后，为他们在学术界和工业界的职业生涯做准备。参与该研究项目的学生中有一半以上是女性或来自未被充分代表的少数族裔。该项目还与爱荷华州小型学院的教师保持积极合作，加强他们的研究和教学。

Mineral dust aerosol plays a critical role in the atmosphere. Dust affects the Earth's radiation balance by direct absorption and scattering of light across the spectrum from infrared (IR) to ultraviolet (UV). Atmospheric dust particles also serve as sites for cloud nucleation indirectly affecting albedo, and as reactive surfaces for tropospheric reactions altering the chemical balance for important gas phase species such as SO2. Correctly modeling the effects of dust in weather, climate, and air quality requires accurate information about dust loading and composition, size and shape (CSS) distributions, as well as proper treatment of dust optical (scattering and absorption) properties. Dust loading and CSS distributions can be obtained by optical remote sensing. However, remote sensing dust retrievals also depend critically on an accurate treatment of aerosol optical properties. Thus, uncertainties in dust optical properties can lead to errors in estimated dust loading, and CSS distributions with deleterious consequences for weather and air quality forecasts and climate modeling.Intellectual merit. We will investigate dust optical properties across the IR-UV spectrum through laboratory measurements and modeling analyses. The study will focus on authentic dust samples. Aerosol extinction and light scattering properties will be analyzed by measurements of particle CSS distributions through real-time in situ single particle time-of-flight mass spectrometry and particle sizing, and various ex situ methodologies. Since the particle CSS distributions will be measured simultaneously with the optical properties, detailed comparisons with theoretical simulations will be possible, with few (or no) adjustable parameters.The main goals of this work are to establish methods for using spectroscopic and polarimetric measurements to infer mineral dust aerosol CSS distributions, and to explore how these distributions may be altered by atmospheric aging. The qualitative insight and quantitative data provided by this work can be incorporated into remote-sensing retrieval algorithms, improving the reliability of aerosol radiative transfer models for dust retrievals and climate forcing calculations, and thus transforming our understanding of the impact of dust on atmospheric chemistry, dynamics, and climate.Broader impacts. The proposed activities offer tremendous opportunities for post-doctoral fellows and students to develop as independent scientists. This research includes aspects of experimental aerosol science, light scattering, spectroscopy, and reaction kinetics studies, combined with an extensive theoretical modeling program. Students participate in all facets of the work, presenting their results at seminars and conferences. The PIs, through a long standing collaboration, have successfully mentored students andpost-doctors at all levels in preparation for professional careers in academia and industry. More than half of the students involved in the research program have been women or from underrepresented minorities. The program also maintains active collaborations with faculty from small colleges in state Iowa, enhancing their research and teaching.