SGER: Parameterization of Sea-Salt Cloud Condensation Nuclei (CCN) Production for 3-D Earth System Models

最近基于环境空气中气溶胶测量的研究提供了证据，表明海洋表面破裂气泡形成的薄膜液滴产生了高浓度的初级、亚微米、富含有机的气溶胶，可能对云层特性和气候反馈产生重要影响。如果海洋表面破裂的气泡是全球海洋上吸湿性、富含有机物质的亚微米气溶胶的主要来源，那么目前没有考虑这些途径的模型可能会大大高估气溶胶成核作为云凝结核(CCN)来源和相关间接气候强迫的重要性。然而，亚微米级气溶胶的长寿命(许多天)，加上新鲜海洋气溶胶的快速化学转化(秒)，严重限制了根据环境空气中对涉及海洋、人为和生物前体的初级(机械)和次级(冷凝)途径的有机贡献进行可靠区分的能力。该项目是关于海盐气溶胶对大气化学和气候影响的更大规模(已经在进行中)调查的一部分。这项更大的研究工作的总体目标是评估1)卤素自由基对对流层臭氧、氧化S、反应氮和相应的氧化能力的影响；2)初级海洋气溶胶作为云凝结核(CCN)的相对重要性。这一SGER项目的主要目标是：开发一种适用于社区气候系统模式(CCSM)和其他全球模式系统的可靠的海洋气溶胶化学和物理特征随风速和表层海洋溶解有机碳(DOC)含量变化的参数。这项工作的完成是CCSM优先发展可靠的气溶胶-云参数以解决气溶胶的间接影响的关键先决条件。更广泛的影响。这个项目将为一名研究生提供支持，并将分析纳入他的论文中。这些成果还将有助于发展可靠的预测能力，以预测对流层气溶胶的产生和间接辐射效应及其对地球气候的相关影响。

Recent investigations based on measurements of aerosols in ambient air provide evidence that film drops from bursting bubbles on the ocean surface produce high concentrations of primary, sub-micron, organic-rich aerosols with potentially important implications for cloud properties and climate feedback. If bursting bubbles on the ocean surface are a major primary source for hygroscopic, organic-rich, sub-micron aerosol over the world's oceans, then current models that do not consider these pathways may substantially overestimate both the importance of aerosol nucleation as a source for cloud condensation nuclei (CCN) and the associated indirect climate forcing. However, the long lifetimes of sub-micron aerosols (many days) coupled with the rapid chemical transformation of fresh marine aerosols (seconds), seriously constrain reliable differentiation based on measurements in ambient air of organic contributions from primary (mechanical) versus secondary (condensation) pathways involving marine, anthropogenic, and biogenic precursors. This project is one component of a larger (already ongoing) investigation of the influence of sea-salt aerosol on atmospheric chemistry and climate. The overall goals of the larger research effort are to evaluate 1) the influences of halogen radicals on tropospheric O3, oxidized S, reactive N, and corresponding oxidative capacity and 2) the relative importance of primary marine aerosol as cloud condensation nuclei (CCN). The principal objective of this SGER project is: To develop a reliable parameterization for the chemical and physical characteristics of primary size-resolved marine aerosol as functions of wind velocity and dissolved organic carbon (DOC) content of the surface ocean that is suitable for application in the Community Climate System Model (CCSM) and other global model systems. Completion of this effort is a critical prerequisite for the CCSM priority of developing reliable aerosol-cloud parameterizations to address the indirect effect of aerosols. Broader Impacts. This project will provide support for one graduate student and the analysis will be incorporated into his dissertation. Results will also contribute to the development of a reliable predictive capability for the production and indirect radiative effects of tropospheric aerosols and the associated influences on Earth's climate.