The partial pressure of carbon dioxide (pCO₂) in surface seawater is an important biogeochemical variable because, together with the pCO₂ in the atmosphere, it determines the direction of air–sea carbon dioxide exchange. Large‐scale observations of pCO₂ are facilitated by Ships‐of‐Opportunity (SOOP‐CO₂) equipped with underway measuring instruments. The need for expanding the observation capacity and the challenges involving the sustainability and maintenance of traditional equilibrator systems led the community toward developing simpler and more autonomous systems. Here we performed a comparison between a membrane‐based sensor and a showerhead equilibration sensor installed on two SOOP‐CO₂ between 2013 and 2018. We identified time‐ and space‐adequate crossovers in the Skagerrak Strait, where the two ship routes often crossed. We found a mean total difference of 1.5 ± 10.6 μatm and a root mean square error of 11 μatm. The pCO₂ values recorded by the two instruments showed a strong linear correlation with a coefficient of 0.91 and a slope of 1.07 (± 0.14), despite the dynamic nature of the environment and the difficulty of comparing measurements from two different vessels. The membrane‐based sensor was integrated with a FerryBox system on a ship with a high sampling frequency in the study area. We showed the strength of having a sensor‐based network with a high spatial coverage that can be validated against conventional SOOP‐CO₂ methods. Proving the validity of membrane‐based sensors in coastal and continental shelf seas and using the higher frequency measurements they provide can enable a thorough characterization of pCO₂ variability in these dynamic environments.

中文翻译：

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在动态货架海环境中基于机会船测量结果的两种pCO2仪器的长期比对

地表海水中的二氧化碳分压（p CO ₂）是重要的生物地球化学变量，因为它与大气中的p CO ₂一起决定了空气与海洋二氧化碳交换的方向。机会船促进了对p CO ₂的大规模观测（SOOP-CO ₂）配备进行中的测量仪器。扩大观测能力的需求以及涉及传统均衡器系统可持续性和维护性的挑战，促使社区开发更简单，更自治的系统。在这里，我们对2013年至2018年间安装在两个SOOP-CO ₂上的基于膜的传感器和莲蓬头平衡传感器进行了比较。我们确定了斯卡格拉克海峡中时间和空间足够的交叉点，两条船路线经常在此交叉。我们发现有1.5±10.6的平均总差μ大气压，11根均方误差 μ大气压。的p CO ₂尽管环境是动态的，并且很难比较两个不同容器的测量值，但两种仪器记录的值显示出很强的线性相关性，系数为0.91，斜率为1.07（±0.14）。基于膜的传感器与FerryBox系统集成在一起，该船在研究区域的采样频率很高。我们展示了拥有一个具有高空间覆盖率的基于传感器的网络的优势，可以通过传统的SOOP-CO ₂方法进行验证。证明基于膜的传感器在沿海和大陆架海中的有效性，并使用它们提供的更高频率测量值，可以对这些动态环境中p CO _2的变化进行全面表征。