Global Impacts of Phase State on Secondary Organic Aerosol Partitioning

本项目主要研究二次有机气溶胶（SOA）的相态（如气粒分割）对区域或全球尺度大气过程的影响。将要开发的参数化可以帮助预测多相化学过程和气溶胶的组成和浓度。本研究的最终目的是评估相态对大气气溶胶过程的全球影响，以更好地预测气溶胶对气候、空气质量和公众健康的影响。目前的大规模SOA模型使用高度简化的平衡气体-颗粒分配方案来表示气溶胶的物理化学过程。本项目将评估在何种条件下以及在何种程度上这些假设在全球大气中可能成立或不成立。实现这一目标的任务如下：(1)在GEOS-Chem模型中实现一种方法来预测SOA的玻璃化转变温度和粘度；(2)利用动力学多层模型推导出全球大气中SOA分配与水分吸收的平衡时间尺度；(3)采用具有有效质量容纳系数的SOA动力学划分方案，考虑相态的影响；(4)根据观察结果评估SOA预算和阶段状态的模型预测。新的气溶胶相态发展将有助于改进GEOS-Chem模型的公共版本，并将向所有用户开放。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project is focused on studying the effects of the phase state (e.g., gas-particle partitioning) of secondary organic aerosol (SOA) on atmospheric processes at regional or global scales. The parameterizations that will be developed can help to predict multiphase chemistry processes and aerosol composition and concentration. The ultimate goal of this research is to evaluate the global impacts of phase state on atmospheric aerosol processes to better predict the aerosol effects on climate, air quality and public health.Current large-scale SOA models represent aerosol physicochemical processes using highly simplified schemes with equilibrium gas-particle partitioning. This project will evaluate under which conditions and to what extent these assumptions may or may not hold in the global atmosphere. The tasks to accomplish this goal are as follows: (1) Implement a method in the GEOS-Chem model to predict glass transition temperatures and the viscosity of SOA; (2) Derive the equilibration timescales of SOA partitioning and water uptake in global atmosphere using kinetic multilayer modeling; (3) Apply a scheme of kinetic partitioning of SOA with effective mass accommodation coefficients to consider the effects of phase state; and (4) Evaluate model predictions of the SOA budget and phase state against observations.The new aerosol phase state developments will contribute to improvements of the public version of the GEOS-Chem model and will be openly available for all users.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.