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，表明海洋表面气泡破裂后的膜滴会产生高浓度的初级、亚微米、富含有机物的气溶胶，这对云的性质和气候反馈具有潜在的重要意义。如果海洋表面的破裂气泡是世界海洋上吸湿性、富含有机物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式可能大大高估了气溶胶成核作为云凝结核（CCN）来源的重要性以及相关的间接气候强迫。然而，亚微米气溶胶的长寿命（许多天）加上新鲜海洋气溶胶的快速化学转化（秒），严重限制了基于环境空气中主要（机械）与次要（冷凝）途径的有机贡献的可靠区分，这些途径涉及海洋、人为和生物前体。这个项目是一个更大的（已经在进行的）海盐气溶胶对大气化学和气候影响调查的一个组成部分。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O3、氧化S、活性N及其氧化能力的影响，以及2)初级海洋气溶胶作为云凝结核（CCN）的相对重要性。SGER项目的主要目标是：开发一种可靠的参数化方法，以确定初级尺寸分辨海洋气溶胶的化学和物理特征作为海洋表面风速和溶解有机碳（DOC）含量的函数，并适用于社区气候系统模式（CCSM）和其他全球模式系统。这项工作的完成是CCSM优先发展可靠的气溶胶-云参数化以解决气溶胶的间接影响的关键先决条件。更广泛的影响。该项目将为一名研究生提供支持，并将分析纳入他的论文。研究结果还将有助于建立可靠的预测能力，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.