Spectral Analysis of Brown Carbon Secondary Organic Aerosol from the IR to the UV

含碳的大气气溶胶，包括黑碳和棕色碳，通过改变大气的光学特性来影响气候，而且它们自己也以一种鲜为人知的方式进行进一步的光化学氧化。这反过来可能会改变它们自身的光学特性。这项工作的总体目标是改善定量模拟有机气溶胶辐射效应的科学基础。研究结果可应用于遥感数据检索算法，提高气溶胶和气候强迫计算辐射传输模型的可靠性，更好地了解棕色碳（BrC）气溶胶对大气化学和气候的影响。在之前的工作中，爱荷华大学的研究人员开发了专门的实验室光学能力来测量尘埃气溶胶在UV-Vis-IR光谱上的光学特性，并探索了气溶胶的物理化学处理如何改变这些特性。在这里，他们将进一步扩展他们的实验能力，采用高灵敏度的技术，腔衰荡激光光谱（CRDS）。这将用于在可见光和中红外光谱范围内精确测量环境和实验室模拟有机气溶胶的棕色碳（BrC）部分的光学特性。这些性质如何随着紫外光化学处理的结果而改变，将进一步研究。

Carbonaceous atmospheric aerosols, including black and brown carbon, impact climate through altering the optical properties of the atmosphere, and also by themselves undergoing further photochemical oxidation, in a poorly understood manner. This in turn may alter their own optical properties. The overall goal of this work is to improve the scientific basis for quantitatively modeling organic aerosol radiative effects. The results have application in remote sensing data retrieval algorithms, improving the reliability of radiative transfer models for aerosol and climate forcing calculations, and better understanding the impact of brown carbon (BrC) aerosol may have on atmospheric chemistry and climate. In previous work, University of Iowa researchers developed specialized laboratory optical capabilities to measure dust aerosol optical properties over the UV-Vis-IR spectrum, and have explored how physicochemical processing of aerosols alters those properties. Here they will further extend their experimental capabilities with a highly sensitive technique, cavity ring down laser spectroscopy (CRDS). This will be used to precisely measure the optical properties of the brown carbon (BrC) fraction of ambient and laboratory mimics of organic aerosols, across the visible and the mid-IR spectral range. How those properties may change as a result of UV photochemical processing will be further studied.