Sub-micron aerosol particle size distribution collected in the Southern Ocean in the austral summer of 2016/2017, during the Antarctic Circumnavigation Expedition.

<strong>Dataset abstract</strong> The authors would highly appreciate to be contacted if the data is used for any purpose. We measured sub-micrometer aerosol particles with two scanning mobility particle spectrometers (SMPSs) between 11 and 400 nm (file name ACESPACE_submicron_aerosol_particle_size_distribution.csv) in 100 bins, and 11 and 181 nm in 77 bins - so no data entry in the remaining 23 bins - (ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv) at a time resolution of five minutes during the Antarctic Circumnavigation Expedition (ACE). Particles in this size range are important for cloud formation because a sub-set of them can act as cloud condensation nuclei (CCN). The time series of the size distribution shows that the particle population over the Southern Ocean can be quite variable featuring three dominant modes: a new particle formation mode (11 – 30 nm); an Aitken mode (20 – 70 nm); and an accumulation mode (&gt; 70 nm). Often a concentration minimum between the Aitken and accumulation mode can be observed. It is known as Hoppel minimum (Hoppel and Frick, 1990; 10.1016/0960-1686(90)90020-N). Typically, particles larger than this minimum act as CCN. The variability of the particle size spectrum is a result of particle sources and atmospheric processes. Sea spray generation adds larger particles likely with a peak in the mode around 200 nm. Trace gas emissions from microbial communities in the ocean, such as dimethylsulfide (DMS) will be oxidized to either sulphuric acid or methanesulfonic acid in the atmosphere which condense onto pre-existing particles, hence growing those. Sulphuric acid can also form new particles (new particle formation mode). Rain and snow will remove particles larger than the Hoppel minimum. The data set can be used to explore the variability of the particle size distribution in three different oceans around Antarctica (Indian, Pacific, Atlantic Oceans) and from Cape Town to Europe in relation to weather patterns, air mass trajectories, microbial activity etc. It is best used in combination with CCN data to explore the importance of particles for cloud formation. This data set cannot be used to unambiguously determine sources of particles over the southern ocean or to trace anthropogenic impact in the region. The data have been cleaned from the influence of the exhaust of the research vessel. We give five-minute average data as dN/dlog(dp), where dN is the particle number concentration per measured size bin normalized over the logarithm of the bin width. The bin width is defined as the distance between two diameters. They are spaced equally in log-space with dlog(dp) = log(d_n+1/d_n) = 1/64. To derive the total particle number concentration between 11 and 400 nm one has to integrate over the diameter range taking into account the normalization by dlog(dp). Temporal coverage is from December 20, 2016 to April 10, 2017. The file “ACESPACE_submicron_aerosol_particle_size_distribution.csv” covers the entire time period except between 9 and 14 January 2017 due to instrument issues. The file “ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv” contains data for the period between 9 and 14 January 2017 and can be used to fill the above gap. The second data file stems from another SMPS with a smaller differential mobility analyser, hence the smaller diameter coverage. <strong>Dataset contents</strong> The data set contains two files with the size distribution of sub-micrometer aerosol particles. The rows are indexed by the time stamp, which is the end of the 5-minutes averaging interval. The columns are the normalized concentrations of particles in the respective size bin. See the data abstract for details. ACESPACE_submicron_aerosol_particle_size_distribution.csv, data file, comma-separated values ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv, data file, comma-separated values ACESPACE_particle_diameter_bins.csv, metadata, comma-separated values data_file_header.txt, metadata, text README.md, metadata, text NaN values in a complete row denote missing values because of e.g., calibration periods, ship exhaust contamination, instrument failure. NaN values which appear individually or only in small groups reflect that data were below detection limit. For latitude and longitude, NaN values are noted in cases where position data was not available for the given time period. <strong>Dataset license</strong> This sub-micron aerosol particle size distribution dataset collected during ACE is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/<strong>数据集摘要</strong> 若本数据集用于任何研究用途，恳请使用者与作者取得联系。我们使用两台扫描迁移率粒子谱仪（scanning mobility particle spectrometers, SMPSs）对亚微米气溶胶粒子开展测量：一组测量范围为11~400 nm，分为100个粒径档，对应文件为ACESPACE_submicron_aerosol_particle_size_distribution.csv；另一组测量范围为11~181 nm，分为77个粒径档，剩余23个粒径档无有效数据，对应文件为ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv。所有测量的时间分辨率为5分钟，实验搭载于南极环极航行（Antarctic Circumnavigation Expedition, ACE）任务中。 该粒径范围内的气溶胶粒子对云形成至关重要，其中部分粒子可作为云凝结核（cloud condensation nuclei, CCN）。粒径分布的时间序列显示，南大洋上空的粒子群体存在显著变化，可分为三种主导模态：新粒子生成模态（11~30 nm）、艾特肯模态（20~70 nm）以及积聚模态（＞70 nm）。通常在艾特肯模态与积聚模态之间可观测到粒子数浓度极小值，该特征被称为霍普尔极小值（Hoppel and Frick, 1990; 10.1016/0960-1686(90)90020-N）。通常，粒径大于该极小值的粒子可作为云凝结核。 粒子粒径谱的变化源于粒子源排放与大气过程：海洋飞沫生成会产生较大粒径的粒子，其数浓度模态峰值大致位于200 nm附近。海洋微生物群落排放的痕量气体（如二甲基硫，dimethylsulfide, DMS）会在大气中被氧化为硫酸或甲磺酸，这些物质会凝结在已存在的粒子表面，促使粒子粒径增长。硫酸本身也可通过均相成核生成新粒子（对应新粒子生成模态）。雨雪沉降会清除粒径大于霍普尔极小值的粒子。 本数据集可用于探究南极周边三大洋（印度洋、太平洋、大西洋）以及从开普敦至欧洲航线范围内的粒子粒径分布变化，关联气象模式、气团轨迹、微生物活动等研究方向。建议与云凝结核数据结合使用，以深入研究粒子对云形成的影响机制。需注意，本数据集无法明确判定南大洋上空的粒子来源，也无法追溯该区域的人为活动影响。数据已剔除研究船舶排气带来的干扰。 本数据集以$dN/dlog(d_p)$的形式提供5分钟平均数据，其中$dN$为每个粒径档内的粒子数浓度，经档宽对数归一化处理。档宽定义为两个粒径直径之差，各粒径档在对数坐标下均匀分布，满足$dlog(d_p) = log(d_{n+1}/d_n) = 1/64$。若需计算11~400 nm范围内的总粒子数浓度，需结合$dlog(d_p)$的归一化因子，对粒径区间进行积分运算。 数据时间覆盖范围为2016年12月20日至2017年4月10日。文件ACESPACE_submicron_aerosol_particle_size_distribution.csv覆盖了除2017年1月9日至14日之外的全部时段，该时段的缺失源于仪器故障。文件ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv包含2017年1月9日至14日的观测数据，可用于填补上述数据缺口。第二个数据文件来自另一台配备更小差分迁移率分析仪的扫描迁移率粒子谱仪，因此其粒径测量范围更窄。 <strong>数据集内容</strong> 本数据集包含两个亚微米气溶胶粒子粒径分布数据文件。数据行以时间戳为索引，该时间戳对应5分钟平均时段的结束时刻；数据列则对应各粒径档内的归一化粒子数浓度。详细说明请参见数据集摘要。 ACESPACE_submicron_aerosol_particle_size_distribution.csv：数据文件，逗号分隔值格式 ACESPACE_submicron_aerosol_particle_size_distribution_nano.csv：数据文件，逗号分隔值格式 ACESPACE_particle_diameter_bins.csv：元数据文件，逗号分隔值格式 data_file_header.txt：元数据文件，纯文本 README.md：元数据文件，纯文本 整行出现的NaN值代表数据缺失，成因包括校准时段、船舶排气污染、仪器故障等；单个或少量分散的NaN值则代表粒子数浓度低于检测限。对于纬度和经度字段，若对应时段无位置数据，则以NaN值标记。 <strong>数据集许可</strong> 本数据集采集自南极环极航行（ACE）任务，采用知识共享署名4.0国际许可协议（Creative Commons Attribution 4.0 International License, CC BY 4.0）进行发布，协议全文可访问https://creativecommons.org/licenses/by/4.0/ 查阅。