Collaborative Research: Hygroscopic Properties of Aerosol Organics

气溶胶通过吸收和散射光线直接促进地球的辐射平衡，并通过使云滴成核间接增加地球的反照率。这两种影响都取决于吸湿性的增长，但有机物对气溶胶吸湿性的贡献还没有被很好地理解--限制了对这些影响进行建模的努力。这项研究将通过现场测量、实验室实验和模拟来解决关于气溶胶吸湿性的几个重要问题：(1)在亚饱和和过饱和条件下，水溶性有机碳(WSOC)对吸湿增长的贡献是什么？(2)WSOC的化学和物理性质是什么？(3)Köhler理论和热力学平衡模型能在多大程度上解释观测到的无机和有机混合气溶胶的吸湿增长和云凝结核(CCN)活动？为了回答这些问题，夏季将在沙漠研究所的高海拔风暴峰实验室(SPL)收集气溶胶样本。样品的详细无机和有机成分将用最先进的分析技术进行测量，以确定迄今未发现的高分子量WSOC。样品的水提取物和分离的WSOC将被重新雾化，以直接测量它们对吸湿生长和CCN活性的贡献。测量的生长因子和CCN活性将使用Köhler理论和基于结构的热力学活动模型进行协调。这项工作的结果将提高模拟混合无机和有机组成的气溶胶的吸湿生长的能力。在这个项目中产生的高相对分子质量WSOC化合物的显式处理将被纳入E-AIM热力学平衡模型的在线版本中，供世界各地的研究人员和学生使用。最终，该项目的结果将提供可纳入大型气候模型的信息，以更好地预测直接和间接的气溶胶辐射效应，如水溶性有机物的吸湿-生长曲线和不同无机和有机组成的气溶胶的Köhler理论的参数化。这项研究将被纳入学生项目，作为风暴峰地球科学研究(GRASP)活动的一部分，该活动吸引来自代表性不足群体的学生。在2010年冬季，SPL还将为几所大学举办大气科学实地课程。该项目将允许参加这些课程的学生在实地部署期间与项目研究人员合作。来自相关研究小组的本科生研究生参与实验室实验、数据分析和结果发布。

Aerosols contribute to the Earth's radiation balance directly by absorbing and scattering light and indirectly by nucleating cloud droplets which increase planetary albedo. Both effects depend on hygroscopic growth, but the contribution of organics to aerosol hygroscopicity is not well understood--limiting efforts to model those effects. This study will address several important questions regarding aerosol hygroscopicity through field measurements, laboratory experiments, and modeling: (1) What is the contribution of water-soluble organic carbon (WSOC) to hygroscopic growth under sub- and super-saturated conditions?; (2) What are the chemical and physical properties of WSOC?; and (3) How well can Köhler theory and thermodynamic equilibrium modeling account for observed hydroscopic growth and cloud condensation nucleus (CCN) activity of mixed inorganic and organic aerosols? To answer these questions, aerosol samples will be collected at the Desert Research Institute's high-elevation Storm Peak Laboratory (SPL) during summer. Detailed inorganic and organic composition of the samples will be measured with state-of-the-art analytical techniques to identify heretofore unspeciated high molecular weight WSOC. Water extracts of the samples and isolated WSOC will be re-aerosolized to directly measure their contribution to hygroscopic growth and CCN activity. Measured growth factors and CCN activity will be reconciled using Köhler theory and structure-based thermodynamic activity models. The results of this work will improve ability to simulate hygroscopic growth for aerosols of mixed inorganic and organic composition. The explicit treatment of high molecular weight WSOC compounds produced in this project will be incorporated into the on-line version of the E-AIM thermodynamic equilibrium model for use by researchers and students worldwide. Ultimately, the project's results will provide information that can be incorporated into large-scale climate models to better predict direct and indirect aerosol radiative effects, such as hygroscopic-growth curves for water soluble organics and parameterizations of Köhler theory for aerosols of different inorganic and organic composition. The research will be incorporated into student projects as part of the Geoscience Research at Storm Peak (GRASP) activity, which engages students from underrepresented groups. During the winter of 2010, SPL will also host atmospheric science field courses for several universities. The project will allow the students taking these courses to work together with project researchers during the field deployment. Graduate undergraduate students from the involved research groups participate in laboratory experiments, data analysis, and publication of the results.