Collaborative Research: EAGER: Design, Fabrication, and Performance Evaluation of a Marine Aerosol Generator for Shipboard Deployment

海洋表面气泡破裂产生海洋气溶胶是地球气候系统的一个重要过程，对对流层的物理化学演化和上层海洋生物地球化学的反馈具有重要意义。海洋气溶胶的可靠表征是评估随后的物理化学演化和反馈的性质和规模的关键先决条件。然而，新鲜的海洋气溶胶通过与光和活性气体的相互作用而迅速改变，并被注入含有机械产生的气溶胶和来自多个来源的相关反应产物以及来自成核和生长途径的二次气溶胶的大气中。因此，基于对环境气溶胶的测量，要明确地消除新生海洋气溶胶的物理化学性质和全球意义是极其困难的。几年前，在美国国家科学基金会的支持下，纽约州立大学环境科学与林业学院和弗吉尼亚大学的研究人员在百慕大制造、测试并成功部署了一种新型的高容量气溶胶发生器，以确定新生海洋气溶胶在完整相关尺寸分布（0.013至15 ìm直径，80% RH）下的产生、特性和光化学演变。合乎逻辑的下一步是在海上的船上部署一个强化版的发生器，以评估海洋有机物组成和浓度对相应的物理化学特征和海洋气溶胶演变的影响，以及由此产生的对海洋表面的反馈。在这个项目中，斯克里普斯海洋研究所的同事将加入同一个研究小组，在船上部署发电机。研究目标是：(1)构建和实验室测试强化版海洋气溶胶发生器，(2)在海上船舶上部署和操作发生器，以及(3)评估结果数量大小分布的代表性。原来的发电机将被修改，使其适合在海上部署。它将在2010年春末或夏初部署在北大西洋一艘中大型机遇号船的扇尾上。气溶胶将在一定的气泡速率和喷嘴流出的水流速率范围内产生。尺寸分辨数生产通量将在全尺寸分布（0.13至15 ìm直径在80% RH）上进行量化。更广泛的影响：结果将为评估表层海洋对主要海洋气溶胶的大小分辨组成和通量的影响，通过海洋来源的颗粒有机物的光化学转化产生的反应性微量气体的种类和大小，以及这些途径在海洋空气、表层海洋生物地球化学和地球气候的多相化学和物理演化中的相关影响提供良好的表征能力。因此，该项目将直接有助于研究海洋气溶胶的化学和物理演变及其相关气候影响的国家和国际计划，以及了解大气在上层海洋生物地球化学动力学中的作用的研究。特别是，这项技术有望与国际和国家表面海洋低层大气研究（SOLAS）相关。该项目还将有助于培养一名学生和博士后。

Production of marine aerosols by bursting bubbles at the ocean surface is a major process in the Earth's climate system, with important implications for the physiochemical evolution of the troposphere and feedbacks on upper ocean biogeochemistry. Reliable characterization of marine aerosols is a critical prerequisite for evaluating the nature and magnitude of subsequent physiochemical evolution and feedbacks. However, fresh marine aerosols are rapidly modified via interaction with light and reactive gases and are injected into an atmosphere containing mechanically produced aerosols and associated reaction products from multiple sources and secondary aerosols from nucleation and growth pathways. Consequently, it is extremely difficult to unequivocally deconvolute the physiochemical properties and global significance of nascent marine aerosols based on measurements of ambient aerosols. Several years ago with NSF support, researchers at the SUNY College of Environmental Science and Forestry and the University of Virginia fabricated, tested, and successfully deployed a novel high-capacity aerosol generator at Bermuda to determine the production, characteristics, and photochemical evolution of nascent marine aerosols over the full relevant size distribution (0.013 to 15 ìm diameter at 80% RH). The logical next step is to deploy a hardened version of the generator on a ship at sea to evaluate the influence of marine organic matter composition and concentration on corresponding physiochemical characteristics and evolution of marine aerosol and the resulting feedbacks on the surface ocean. In this project, the same research team will be joined by colleagues at the Scripps Institution of Oceanography to deploy the generator on a ship. The research objectives are: (1) To construct and lab-test a hardened version of the marine aerosol generator, (2) to deploy and operate the generator on a ship at sea, and (3) To evaluate the representativeness of resulting number size distributions. The original generator will be modified to make it suitable for deployment at sea. It will be deployed in a shelter on the fantail of a medium- to large-size ship of opportunity in the North Atlantic during late spring or early summer 2010. Aerosols will be generated over a range of bubble rates and falling water flow rates from the nozzle. Size-resolved number production fluxes will be quantified over the full size distribution (0.13 to 15 ìm diameter at 80% RH). Broader Impacts: Results will provide a well-characterized capability for evaluating the influences of the surface ocean on the size-resolved composition and flux of primary marine aerosols, the speciation and magnitude of reactive trace gas production via photochemical transformation of marine-derived particulate organic matter, and the related influences of these pathways in the multiphase chemical and physical evolution of the marine air, surface ocean biogeochemistry, and Earth's climate. Consequently, the project will contribute directly to national and international programs investigating the chemical and physical evolution of marine aerosols and their related climatic implications as well as studies on understanding the role of the atmosphere on the upper ocean's biogeochemical dynamics. In particular this technology promises to be relevant to the international and national Surface Ocean Lower Atmosphere Study (SOLAS). The project will also contribute to the education of a student and post doctoral fellow.