Abstract. Atmospheric particles can impact cloud formation and play a critical role in regulating cloud properties. However, particle characteristics at the single-particle level and their ability to act as ice-nucleating particles (INPs) over the marine atmosphere are poorly understood. In this study, we present micro-spectroscopic characterizations and ice nucleation properties of particles collected during a cruise from South Korea to Antarctica in 2019. Most of the samples were dominated by fresh sea salt, aged sea salt, and sea salt mixed with sulfate particles, with total number percentages ranging from 48 % to 99 % over the western Pacific and the Southern Ocean. The mixing-state index of the particle population ranged from 50 % to 95 % over the Northern Hemisphere and Southern Hemisphere. Multiphase processes on sea salt particles resulted in chlorine deficiency. This selective aging process made the marine particle population more externally mixed. Ice nucleation onset conditions primarily for the deposition mode were measured and the investigated particles showed diverse ice nucleation abilities. The fresh sea salt particles with organic coatings exhibited the highest ice nucleation ability at a relative humidity with respect to ice as low as 121 %. The sea salt mixed sulfate particle was enriched in INPs by a factor of 1.9. Aging processes affected both the mixing state of the particles and their ice nucleation abilities. Our analysis shows that assuming an internally mixed particle population in the marine atmosphere can lead to errors of several orders of magnitude in predicting ice nucleation rates.

中文翻译：

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不同的来源和老化改变了西太平洋和南大洋上空气溶胶颗粒的混合状态和冰核特性


摘要。大气颗粒物可以影响云的形成，并在调节云特性方面发挥关键作用。然而，人们对单粒子水平的粒子特征及其在海洋大气中充当冰核粒子（INP）的能力知之甚少。在这项研究中，我们展示了 2019 年从韩国到南极洲的航行期间收集的颗粒的微观光谱特征和冰成核特性。大多数样本主要是新鲜海盐、陈化海盐以及与硫酸盐颗粒混合的海盐，在西太平洋和南大洋上空的总数百分比从 48% 到 99% 不等。北半球和南半球的粒子群混合态指数范围为 50% 至 95%。海盐颗粒的多相过程导致氯缺乏。这种选择性老化过程使海洋颗粒群在外部更加混合。测量了主要针对沉积模式的冰成核起始条件，并且研究的颗粒表现出不同的冰成核能力。具有有机涂层的新鲜海盐颗粒在相对于冰的相对湿度低至 121% 时表现出最高的冰成核能力。海盐混合硫酸盐颗粒的 INP 富集度为 1.9 倍。老化过程影响颗粒的混合状态及其冰成核能力。我们的分析表明，假设海洋大气中存在内部混合的粒子群，可能会导致预测冰成核率出现几个数量级的误差。