MOSAiC-Colorado State University Ice Spectrometer

This data set contains atmospheric ice nucleating particle (INP) measurements, using Colorado State University’s (CSU) Ice Spectrometer (IS), of filter collections taken at the U.S. DOE ARM AMF2 site onboard the R/V Polarstern P-deck during the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) field campaign. Samples were collected from October 27, 2019 to September 24, 2020. A filter sampler was mounted approximately 15 m above ground level on a railing in proximity to (and approximately 3 m below) the Aerosol Observation System (AOS) inlet. Single-use filter units open to the atmosphere were pre-cleaned and pre-loaded with 47-mm diameter Nuclepore polycarbonate (0.2 µm pore-diameter) filters. Filters were typically drawn for a three-day period, with an average volume of air filtered of 87,000 standard liters. Total volumes were calculated through recorded daily flow rates using a mass flow meter (TSI). After collection, filters were stored and transported frozen until analysis using CSU’s IS instrument (McCluskey et al., 2018). Aerosol particles were first re-suspended in 8 mL of 0.1 µm-filtered deionized (DI) water. Aliquots of each suspension, and corresponding 11-fold dilutions, were dispensed into polymerase chain reaction (PCR) trays and placed into the aluminum blocks of the IS. Samples were cooled at approximately 0.33 °C min-1 and freezing detected optically with corresponding temperatures recorded. Cumulative INP concentrations were determined through calculating the number of INPs per mL of suspension (Vali, 1971) and converting to concentration per standard L of air by accounting for the proportion of liquid used and volume of air collected. All samples were corrected for the number of INPs on the average of four field blanks (cleaned, handled, transported, and analyzed in the same way without air flow). Two-tailed, 95% confidence intervals for binomial sampling are provided (Agresti and Coull, 1998). Select samples were also heat treated (95 °C for 20 min) to denature and deactivate biological INPs present and digested in 10% H2O2 at 95 °C under UV-B for 20 min to remove any organic carbon INPs. Agresti, A, and BA Coull. 1998. "Approximate is better than “exact” for interval estimation of binomial proportions." American Statistics 52: 119–126. https://doi.org/10.2307/2685469 McCluskey, CS, J Ovadnevaite, M Rinaldi, J Atkinson, F Belosi, D Ceburnis, … and PJ DeMott. 2018. "Marine and Terrestrial Organic Ice-Nucleating Particles in Pristine Marine to Continentally Influenced Northeast Atlantic Air Masses." Journal of Geophysical Research: Atmospheres 123(11): 6196–6212, https://doi.org/10.1029/2017JD028033 Vali, G. 1971. "Quantitative Evaluation of Experimental Results and the Heterogeneous Freezing Nucleation of Supercooled Liquids." Journal of the Atmospheric Sciences 28: 402-209. https://doi.org/10.1175/1520-0469(1971)028<0402:QEOERA>2.0.CO;2

本数据集包含大气冰核粒子（atmospheric ice nucleating particle，INP）测量数据，采用科罗拉多州立大学（Colorado State University，CSU）冰谱仪（Ice Spectrometer，IS）完成，样品为美国能源部（U.S. DOE）大气辐射测量（Atmospheric Radiation Measurement，ARM）AMF2站点在北极气候多学科漂流观测站（Multidisciplinary Drifting Observatory for the Study of Arctic Climate，MOSAiC）野外考察期间，搭载于极地号科考船（R/V Polarstern）P甲板采集的滤膜样品。采样时段为2019年10月27日至2020年9月24日。

滤膜采样器安装于距地面约15米的栏杆上，紧邻气溶胶观测系统（Aerosol Observation System，AOS）进气口（且距其下方约3米处）。采用暴露于大气的一次性滤膜采样单元，预先完成清洁处理并预装直径47毫米、孔径0.2微米的Nuclepore聚碳酸酯滤膜。单次采样周期通常为3天，平均过滤空气体积达87000标准升。总过滤体积通过质量流量计（TSI）记录的每日采样流量计算得到。

采样完成后，滤膜经冷冻储存与运输，直至采用CSU的IS仪器开展分析（McCluskey等，2018）。首先将采集的气溶胶粒子重悬于8毫升经0.1微米过滤的去离子（deionized，DI）水中。将每份悬浮液及其11倍梯度稀释液移液至聚合酶链式反应（polymerase chain reaction，PCR）板中，随后放入IS仪器的铝制样品块内。样品以约0.33℃·min⁻¹的速率降温，通过光学方法检测冻结过程并同步记录对应温度。累积INP浓度通过计算每毫升悬浮液中的INP数量确定（Vali，1971），并结合所用悬浮液体积与采集空气体积的比例，转换为每标准升空气的INP浓度。

所有样品均根据4份现场空白样品（采用相同流程完成清洁、处理、运输与分析但未通入空气）的平均INP数量进行空白校正。同时提供二项抽样的双侧95%置信区间（Agresti与Coull，1998）。部分样品还经热处理（95℃持续20分钟）以变性灭活其中存在的生物性INP，或在95℃、UV-B辐照下用10%过氧化氢（H₂O₂）消解20分钟以去除有机碳类INP。

参考文献：
1. Agresti, A, 与BA Coull. 1998. "Approximate is better than “exact” for interval estimation of binomial proportions"（《二项分布区间估计中近似法优于“精确法”》）. 《美国统计学家》（American Statistics）52: 119–126. https://doi.org/10.2307/2685469
2. McCluskey, CS, J Ovadnevaite, M Rinaldi, J Atkinson, F Belosi, D Ceburnis, 等与PJ DeMott. 2018. "Marine and Terrestrial Organic Ice-Nucleating Particles in Pristine Marine to Continentally Influenced Northeast Atlantic Air Masses"（《原始纯净海洋到受大陆影响的东北大西洋气团中的海洋与陆地有机冰核粒子》）. 《地球物理研究杂志：大气》（Journal of Geophysical Research: Atmospheres）123(11): 6196–6212, https://doi.org/10.1029/2017JD028033
3. Vali, G. 1971. "Quantitative Evaluation of Experimental Results and the Heterogeneous Freezing Nucleation of Supercooled Liquids"（《过冷液体实验结果的定量评估与非均相冻结成核》）. 《大气科学杂志》（Journal of the Atmospheric Sciences）28: 402-209. https://doi.org/10.1175/1520-0469(1971)028<0402:QEOERA>2.0.CO;2