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

这个急切的项目利用了一个独特的机会，在已经组织的研究巡航中携带了海洋边界层大气成分的重要测量结果。该项目的主要目标是确定和量化对太平洋上空云凝结核(CCN)种群的生物成因贡献。为了实现这一主要目标，将在汤姆汤普森房车上进行一次研究巡航期间进行观察。大气科学和生物海洋学的技术将以一种新的跨学科方法结合起来，以观测海面水域附近和水面上方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：在巡航轨道沿线的所有点，将直接现场测量环境气溶胶的浓度和作为CCN的活性部分。海水产生的气溶胶的CCN测量：将从表层水域采集海水样本。海水将被分成几个样本，其中包含不同大小的生物来源物质。这些将包括细菌(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(大于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，含有这些组分的海水样本将被单独重新雾化，并通过CCN监测仪器发送气溶胶以确定其活性。因此，将评估与CCN活动有关的海洋生物来源材料的粒度比例。辅助测量：将使用卫星图像和现场水测量来评估样本所在区域的生物活动。此外，还将收集关于周围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颗粒物样本，以便进行大量化学和生物分析。对收集到的气溶胶、分馏海水样本中的气溶胶和海水样本的分析将用于确定关键的海洋和非海洋化合物，并确定其在海洋中的浓度与其在海面上的气溶胶浓度之间的关系。为了帮助区分在气溶胶中发现的海洋和非海洋物质来源，将使用气象观测以及气象回溯轨迹分析。广泛影响：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成分。生物成因的海洋气溶胶可能对云的时空分布和随后的降水模式产生深远影响。关于气溶胶及其上形成的云层的辐射影响的知识有限，是理解地球辐射预算和气候变化的一个主要不确定性。这一跨学科项目包括来自两个系的研究人员，并将构成海洋学和大气科学系教员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舰载培训。还将支持海洋学系的一名研究生参与这项研究。结果将在科学会议和同行评议的文献中传播

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