Clouds, fogs, and rain can serve as useful integrators of both atmospheric aerosols and soluble trace gases. To better understand the chemical characteristics of sea fog and rain in the North and South Pacific Ocean, fog and rain were measured aboard the R/V ARAON in 2012 and 2014, respectively, as part of the Ship-borne Pole-to-Pole Observations (SHIPPO) project. The mean sea fog pH (3.59) was lower than the mean rain pH (4.54), reflecting greater inputs of non-sea-salt (nss)-SO42−. For the collected rain, nss-Ca2+ and nss-Mg2+ from mineral dust particles were the major contributors to acidity neutralization. NO3− concentrations, which are derived from scavenging of gaseous nitric acid and aerosol nitrate, were higher than NH4+ concentrations, indicating that terrestrial and/or local anthropogenic NO3− sources outweighed contributions from anthropogenic or biological oceanic NH3/NH4+ sources. The ratio of Cl−/Na+ in the sea fog was slightly lower than that in the sea water due to HCl volatilization from scavenged sea-salt particles. The ratio of NH4+/ nss-Ca2+ was lower in the rain than in the sea fog, revealing the influence of mineral dust particles at altitudes above the sea fog layer. The average sea fog water TOC concentration, 13.2 ppmC, was much higher than the measured TOC concentrations in marine fogs and clouds in other remote environments, likely due to continental influence; the TN and TOC concentrations in the fog water were much higher than those in the rain. The sea fog and rain chemical properties measured during research cruises like these enhance our understanding of wet deposition and cloud condensation nuclei sources and processes in the Pacific Ocean.

中文翻译：

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北太平洋和南太平洋海雾和雨化学的船载观测

云、雾和雨可以作为大气气溶胶和可溶性微量气体的有用积分器。为了更好地了解北太平洋和南太平洋海雾和雨的化学特征，作为船载极对极观测的一部分，分别于 2012 年和 2014 年在 R/V ARAON 上测量了雾和雨(SHIPPO) 项目。平均海雾 pH 值 (3.59) 低于平均雨 pH 值 (4.54)，反映了非海盐 (nss)-SO42− 的更大输入。对于收集到的雨水，来自矿物尘埃颗粒的 nss-Ca2+ 和 nss-Mg2+ 是酸度中和的主要贡献者。NO3− 浓度源自气态硝酸和气溶胶硝酸盐的清除，高于 NH4+ 浓度，表明陆地和/或本地人为 NO3− 源的贡献超过了人为或生物海洋 NH3/NH4+ 源的贡献。由于 HCl 从清除的海盐颗粒中挥发，海雾中 Cl−/Na+ 的比率略低于海水中的比率。雨中NH4+/nss-Ca2+的比值低于海雾中，揭示了海雾层以上海拔高度处矿物尘埃颗粒的影响。海雾水的平均 TOC 浓度为 13.2 ppmC，远高于在其他偏远环境中测量的海雾和云中的 TOC 浓度，这可能是由于大陆的影响；雾水中的TN和TOC浓度远高于雨中。