EAGER: Marine Biogenic Aerosols as Cloud Condensation Nuclei over the Pacific Ocean

这个EAGER项目利用了一个独特的机会，在一个已经组织好的研究巡航中携带海洋边界层大气成分的重要测量数据。该项目的主要目标是确定和量化生物对太平洋云凝结核（CCN）种群的贡献。为了实现这一主要目标，观测将在RV汤姆·汤普森的研究巡航期间进行。大气科学和生物海洋学的技术将结合在一个新的跨学科方法中，以观察海洋表层水域附近和地表以上空气中的海洋生物物质，并监测近地表气溶胶的一般物理和化学性质。这项工作将通过以下步骤完成：环境气溶胶的CCN活性：在巡航轨道的所有点，将对环境气溶胶的浓度和作为CCN活性的部分进行直接现场测量。由海水产生的气溶胶的CCN测量：将从地表水收集海水样本。海水将被分离成含有不同大小生物物质的几个样品。这些包括细菌（0.2微米直径2.0微米）、病毒（0.02微米直径0.2微米）、高分子量溶解有机物（超过1000个原子质量单位，但直径为0.02微米）和低分子量有机分子（1000个原子质量单位）。在船上，含有这些馏分的海水样品将被单独重新雾化，气溶胶将通过CCN监测仪器发送，以确定其活性。因此，将评估造成CCN活性的海洋生物物质的大小比例。辅助测量：卫星图像和原位水测量将用于评估从中获取样本的区域的生物活动。将收集额外的环境气溶胶浓度和大小的现场大气观测数据，以及在过滤器上收集的空气中颗粒样本，用于大量化学和生物分析。对收集到的气溶胶、分馏海水样本的气溶胶和海水样本的分析将用于确定主要的海洋和非海洋化合物，并确定它们在海洋中的浓度与它们在海上气溶胶中的浓度之间的关系。为了帮助区分气溶胶中物质的海洋和非海洋来源，气象观测和气象反轨迹分析将被采用。更广泛的影响：这项研究将确定将海洋生物生产与海洋气溶胶和云成核过程联系起来的关键组成部分。生物源性海洋气溶胶可能深刻影响云的时空分布和随后的降水模式。关于气溶胶和在其上形成的云的辐射效应的知识的局限性是了解地球辐射收支和气候变化的一个主要不确定性。这个跨学科项目包括来自两个系的研究人员，并将成为海洋学和大气科学系教师之间继续合作的基础。该项目将为大气科学系的一名博士后研究员提供船舶培训。海洋学系的一名研究生也将被支持参与研究。研究结果将在科学会议和同行评议的文献中公布

This EAGER project takes advantage of a unique opportunity to piggyback important measurements of marine boundary layer atmospheric constituents on an already-organized research cruise. The primary objective of this project is to identify and quantify biogenic contributions to cloud condensation nuclei (CCN) populations over the Pacific Ocean. To meet this primary objective, observations will be conducted during a research cruise on the RV Tom Thompson. Techniques from atmospheric sciences and biological oceanography will be combined in a novel interdisciplinary approach to observe marine biogenic material near the sea surface waters and in the air above the surface, and monitor the general physical and chemical properties of the near-surface aerosol. The work will be accomplished through the following steps: CCN activity of ambient aerosols: At all points along the cruise track, direct in situ measurements will be made of the concentration of ambient aerosols and the fraction active as CCN. CCN measurements of aerosols generated from sea water: Seawater samples will be collected from the surface waters. The seawater will separated into several samples containing different size fractions of biogenic material. These will include bacteria (0.2 micrometer diameter 2.0 micrometer), viruses (0.02 micrometer diameter 0.2 micrometer), high molecular weight dissolved organic matter ( more 1000 atomic mass units, but with diameter 0.02 micrometer), and low molecular weight organic molecules ( 1000 atomic mass units). Onboard the ship, the sea water samples containing each of these fractions will be re-aerosolized individually and the aerosol sent through a CCN monitoring instrument to determine its activity. Thus the size fraction of marine biogenic material responsible for CCN activity will be assessed. Supporting measurements: Satellite images and in situ water measurements will be used to assess biological activity in the regions from which samples are obtained. Additional in situ atmospheric observations of the concentration and sizes of ambient aerosols will be collected, along with airborne particulate samples collected on filters for bulk chemical and biological analysis. Analysis of the collected aerosols, aerosol from fractionated seawater samples, and seawater samples will be used to identify key marine and non-marine compounds and to determine how their concentrations in the sea may be related to their concentrations in aerosol above the sea. To help differentiate between marine and non-marine sources of materials found in the aerosol, meteorological observations as well as meteorological back trajectory analyses will be employed.Broader Impacts: This research will identify the key components linking biological production in the ocean to marine aerosols and cloud nucleation processes. Biogenic marine aerosol may profoundly affect the spatial and temporal distribution of clouds and subsequent precipitation patterns. Limitations in knowledge concerning the radiative effects of aerosols and the clouds which form on them represent a major uncertainty in understanding the earth's radiative budget and climate change. This interdisciplinary project includes investigators from two Departments and will form the basis for continued collaboration between faculty in the Departments of Oceanography and Atmospheric Sciences. The project will provide ship-based training for a post-doctoral researcher in the Department of Atmospheric Sciences. A graduate student from the Department of Oceanography will be supported as well to participate in the research. Results will be disseminated at scientific meetings and in the peer-reviewed literature