Coarse and Fine Aerosol Composition during the Pacific Atmospheric Sulfur Experiment (PASE)

作为太平洋大气硫实验(PASE)的一部分，NSF/NCAR C-130飞机将测量热带海洋边界层(MBL)中非海盐硫酸盐(NSS)、甲烷磺酸盐(MSA)和其他气溶胶物种的浓度。PASE是一项关于将海洋排放的二甲基硫(DMS)与气溶胶的形成和生长联系起来的硫化学的综合研究；它将于2007年8月/9月在赤道太平洋圣诞岛附近举行。集成过滤器和冲击器收集将用于准确测量气溶胶成分作为颗粒大小、海拔和一天中的时间的函数。总气溶胶采样器(TAS)将产生高度准确和精确的每个主要离子的总浓度。微孔冲击器(MOI)将被用来研究各种粒度范围内NSS与海盐的比例等密集量。这些方法相对较慢，但在圣诞岛之前的一次实验中，它们被证明非常适合于含硫气溶胶日变化的高精度研究。气溶胶成分测量将与气相硫数据一起使用，以限制硫物种的预算。需要解决的关键问题是：硫酸盐的每日增加是否可以量化，以及排放的DMS中有多少成为NSS和MSA？更广泛的科学影响集中在更好地了解海洋硫循环，它将生物过程、大气-海洋交换、DMS光化学、气溶胶形成和增长、云特性和地球辐射收支联系在一起。关闭以DMS为主的地区的硫收支将对气候模型中使用的海洋气溶胶模块提供强有力的限制，并最终可能提高气候评估的准确性。一名研究生也将参加PASE。

Concentrations of non-sea salt sulfate (NSS), methane sulfonate (MSA), and other aerosol species in the tropical marine boundary layer (MBL) will be measured from the NSF/NCAR C-130 aircraft, as part of the Pacific Atmospheric Sulfur Experiment (PASE). PASE is a comprehensive study of the sulfur chemistry that connects dimethyl sulfide (DMS) emissions from the ocean to aerosol formation and growth; it will take place near Christmas Island in the Equatorial Pacific in August/September 2007. Integrating filter and impactor collections will be used to accurately measure aerosol composition as a function of particle size, altitude, and time of day. A total aerosol sampler (TAS) will produce a highly accurate and precise total concentration of each major ion. A micro-orifice impactor (MOI) will be used to study intensive quantities such as the ratio of NSS to sea salt in each size range. These methods are relatively slow but they have been shown in a previous Christmas Island experiment to be well suited to high-precision studies of diurnal variations in sulfur-containing aerosols. The aerosol composition measurements will be used together with gas-phase sulfur data to constrain the budgets of sulfur species. Key questions to be addressed are: Can daily increases in sulfate be quantified, and what fraction of emitted DMS becomes NSS and MSA?Broader scientific impacts center on a better understanding of the marine sulfur cycle, which links biological processes, air-sea exchange, DMS photochemistry, aerosol formation and growth, cloud properties, and Earth's radiation budget. Closing the sulfur budget in a DMS- dominated area will provide a strong constraint to the marine aerosol modules used in climate models and could ultimately improve the accuracy of climate assessments. A graduate student will also participate in PASE.