Abstract. Sulfuric acid (H₂SO₄, SA) is the key compound in atmospheric new particle formation. Therefore, it is crucial to observe its concentration with sensitive instrumentation, such as chemical ionisation inlets coupled to Atmospheric Pressure interface Time-of-Flight mass spectrometers (CI-APi-TOF). However, there are environmental conditions and physical reasons when chemical ionisation cannot be used, for example in certain remote places or flight measurements with limitations regarding chemicals. In these cases, it is important to estimate the SA concentration based on ambient ion composition and concentration measurements that are achieved by APi-TOF alone. Here we derive a theoretical expression to estimate SA concentration and validate it with accurate CI-APi-TOF observations. The developed estimate works very well during daytime and with SA concentrations above 2⋅10⁶ cm^-3.

中文翻译：

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使用环境离子组成和通过离子质谱测量 (APi-TOF) 获得的浓度数据估算硫酸浓度

摘要。硫酸（H ₂ SO ₄, SA) 是大气新粒子形成的关键化合物。因此，使用灵敏的仪器观察其浓度至关重要，例如与大气压力接口飞行时间质谱仪 (CI-APi-TOF) 耦合的化学电离入口。然而，当不能使用化学电离时，存在环境条件和物理原因，例如在某些偏远地方或对化学品有限制的飞行测量。在这些情况下，重要的是根据环境离子组成和单独通过 APi-TOF 实现的浓度测量来估计 SA 浓度。在这里，我们推导出一个理论表达式来估计 SA 浓度，并通过准确的 CI-APi-TOF 观察对其进行验证。开发的估计在白天和 SA 浓度高于 2⋅10 时效果很好⁶厘米^-3。