The majority of the aerosol particle number (condensation nuclei or CN) in the marine boundary layer (MBL) consists of sulfate and organic compounds that have been shown to provide a large fraction of the cloud condensation nuclei (CCN). Here we use submicron non‐refractory Aerosol Mass Spectrometer (AMS) and filter measurements of organic and sulfate components of aerosol particles measured during four North Atlantic Aerosol and Marine Ecosystems Study (NAAMES) research cruises to assess the sources and contributions of submicron organic and sulfate components for CCN concentrations in the MBL during four different seasons. Submicron hydroxyl group organic mass (OM) correlated strongly to sodium concentrations during clean marine periods (R = 0.9), indicating that hydroxyl group OM can serve as a proxy for sea‐spray OM in ambient measurements. Sea‐spray OM contributed 45% of the sum of sea‐spray OM and sea salt during late spring (biomass climax phase) compared to <20% for other seasons, but the seasonal difference was not statistically significant. The contribution of non‐combustion sources during clean marine periods to submicron OM was 47 to 88% and to non‐sea‐salt sulfate 31 to 86%, with likely sources being marine and biogenic. The remaining submicron OM and sulfate were likely associated with ship or continental sources, including biomass burning, even during clean marine periods. The seasonal contribution from secondary sulfate and OM components to submicron aerosol mass was highest during late spring (60%), when biogenic emissions are expected to be highest, and lowest during winter (18%). Removing submicron sea‐spray OM decreased CCN concentrations by <10% because of competing effects from increased hygroscopicity and decreased particle size. During all seasons, adding biogenic secondary sulfate increased hygroscopicity, particle size, and CCN concentrations at 0.1–0.3% supersaturations by 5–66%. The largest change was during early spring when the fraction of hygroscopic sulfate components in the 0.1–0.2 μm size range was highest (80%). During continental periods, the increased contribution from low‐hygroscopicity organic components to 0.1–0.2 μm diameter particles reduces the CCN/CN by 20–100% for three seasons despite the increased CN and mass concentrations. These results illustrate the important role of the chemical composition of particles with diameters 0.1–0.2 μm for controlling CCN in the MBL.

中文翻译：

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北大西洋海洋气溶胶的浓度，化学成分和云凝结核的季节差异和变异性

海洋边界层（MBL）中的大多数气溶胶颗粒数（凝结核或CN）由硫酸盐和有机化合物组成，已显示它们提供了大部分的云凝结核（CCN）。在这里，我们使用亚微米非耐火质气溶胶质谱仪（AMS）和在四个北大西洋气溶胶和海洋生态系统研究（NAAMES）研究航行期间测量的气溶胶颗粒的有机和硫酸盐成分的过滤器测量，来评估亚微米有机物和硫酸盐的来源和贡献四个不同季节中MBL中CCN浓度的化学成分。在清洁海洋时期，亚微米羟基有机物质量（OM）与钠浓度密切相关（R = 0.9），表明羟基OM可以在环境测量中代替海雾OM。在春季（生物质高潮阶段）期间，海喷雾OM占海喷雾OM和海盐总和的45％，而其他季节小于20％，但季节差异在统计学上不显着。在清洁海洋时期，非燃烧源对亚微米OM的贡献为47％至88％，对非海盐硫酸盐的贡献为31％至86％，可能的来源是海洋的和生物的。剩余的亚微米OM和硫酸盐很可能与船舶或大陆来源有关，包括燃烧生物质，即使在清洁的海洋时期也是如此。在春季末期，次生硫酸盐和OM成分对亚微米气溶胶质量的季节性贡献最高（60％），而预计生物源排放量最高，冬季最低（18％）。除去亚微米海喷雾OM，由于吸湿性增加和粒径减小的竞争影响，使CCN浓度降低了<10％。在所有季节中，添加生物成因的仲硫酸盐可增加0.1–0.3％过饱和度的吸湿性，粒径和CCN浓度5-66％。最大的变化是在初春期间，当吸湿性硫酸盐成分在0.1-0.2μm尺寸范围内的比例最高时（80％）。在大陆时期，尽管CN和质量浓度增加，但低吸湿性有机成分对直径0.1-0.2μm颗粒的贡献增加，使CCN / CN在三个季节中降低了20-100％。这些结果说明了直径为0.1–0的颗粒的化学成分的重要作用。