Formation and Growth of Particles in the Troposphere: Modeling, Data Analyses, and Comparisons

气溶胶间接辐射强迫(IRF)在很大程度上由云凝结核(CCN)浓度决定，是评估气候变化的一个主要不确定性来源。最近的全球气溶胶模拟研究表明，对流层CCN丰度和气溶胶IRF对成核机制的选择非常敏感，并强调了进一步改进全球模式中气溶胶成核和增长过程的表示的重要性。该项目旨在通过全面的数据分析、详细的案例研究、亚格子成核模拟和参数化、全球气溶胶模拟以及模型结果与测量结果的比较，促进对大气颗粒物形成和增长过程的理解和减少不确定性。为了实现这些项目目标，已经确定了以下目标/研究任务：(1)对成核观察进行深入的个案研究和分析，以解决关于离子介导成核和中性/均质成核在北方森林中的相对重要性的争议。将通过扩展的案例研究进一步评估和改进IMN模式。(2)研究从现场测量得到的成核率与硫酸蒸气浓度的线性或平方关系，并确定这种关系是否暗示了新的成核机制。(3)分析全球观测到的大量粒子特性数据集，并将其用于评估全球气溶胶模拟，主要侧重于不同成核机制捕捉对流层粒子数浓度的空间和时间变化的能力。(4)研究次网格人为SO2羽流中粒子的形成和生长，以改善羽状尺度过程在全球气溶胶模式中的表现，减少模拟CCN浓度的不确定性。(5)应用改进的全球气溶胶模式研究对流层不同区域CCN的来源及其季节变化。预测的CCN浓度将与测量结果进行比较，并将评估和解决可能的不确定性。该项目将为两名研究生和一名短期访问学生或学者提供教育机会和研究培训。两名研究生研究人员将获得专业经验，以拓宽他们的知识，并为未来的就业提供机会。该项目还将为纽约州立大学奥尔巴尼分校对气溶胶和大气研究感兴趣的本科生提供研究经验和培训。该项目将有助于对气溶胶对地球气候的影响进行量化的持续努力。它将为科学界提供的最新成核率查询表提供支持，并支持改进可用于研究和教育目的的在线成核率计算器。在本项目范围内得出的亚格子硫酸盐颗粒形成的参数将提供给从事区域和全球气溶胶模拟工作的其他研究人员。

The aerosol indirect radiative forcing (IRF), largely determined by the concentrations of cloud condensation nuclei (CCN), is a major source of uncertainty in assessing climate change. Recent global aerosol modeling studies show that tropospheric CCN abundance and aerosol IRF are sensitive to the choice of nucleation mechanism, and emphasized the critical importance of further improvement of the representation of aerosol nucleation and growth processes in global models. This project seeks to advance the understanding and reduce uncertainties of atmospheric particle formation and growth processes via comprehensive data analyses, detailed case studies, sub-grid nucleation modeling and parameterizations, global aerosol modeling, and comparisons of model results with measurements. In order to achieve these project goals, the following objectives/research tasks have been identified:(1) In-depth case studies and analyses of nucleation observations to resolve controversies over the relative importance of ion-mediated nucleation (IMN) and neutral/homogeneous nucleation in boreal forests. An IMN model will be further assessed and improved through extended case studies. (2) Investigate the linear or square dependences of nucleation rates derived from field measurements on the sulfuric acid vapor concentrations, and ascertain whether such dependences imply new nucleation mechanisms. (3) Analyze extensive datasets of particle properties observed around the globe, and use them to assess global aerosol simulations, with the primary focus on the ability of different nucleation mechanisms to capture the spatial and temporal variations of tropospheric particle number concentrations. (4) Study particle formation and growth in sub-grid anthropogenic SO2 plumes, in order to improve the representation of the plume-scale processes in global aerosol models, and to reduce uncertainties in simulated CCN concentrations.(5) Apply an improved global aerosol model for investigating sources of CCN in different tropospheric regions and their seasonal variations. Predicted CCN concentrations will be compared with measurements and possible uncertainties will be assessed and addressed.This project will provide educational opportunities and research training for two graduate students and a short-term visiting student or scholar. Two post-graduate researchers will be given specialized experiences to broaden their knowledge and provide opportunities for the future employment. This project will also provide research experience and training for SUNY Albany undergraduate students who are interested in aerosol and atmospheric research. This project will contribute to on-going efforts to quantify the impacts of aerosols on the Earth's climate. It will provide support for updated nucleation rate look-up tables that have been made available to the scientific community and for the improvement of online nucleation rate calculators, which can be used for both research and educational purposes. Parameterizations of sub-grid sulfate particle formation derived within this project will be made available to other investigators working on regional and global aerosol modeling.