ICOS RI 13d ago

ICOS Talks is a series of online presentations and discussions by scientists, for scientists. These talks showcase groundbreaking greenhouse gas science topics facilitated by ICOS data. Learn more: https://www.icos-cp.eu/news-and-events/talks About the speaker Tobias Steinhoff is a chemical oceanographer at GEOMAR Helmholtz Centre for Ocean Research Kiel specializing in the ocean’s carbon, nutrient, and oxygen cycles. He is operating the Ship-of-Opportunity (SOOP) line DE-SOOP-Atlantic Sail in the North Atlantic Ocean. For more than two decades, he has contributed to international ocean observations and research expeditions across the Atlantic, Pacific, and Indian Oceans. Between 2019 and 2024, he supported ICOS Oceans and led the international pCO2 instrument inter-comparison in 2021. His current focus is on new technologies, autonomous sensors, and international collaborations to improve global ocean observations and data accessibility. Abstract In 2021, the Ocean Thematic Centre of ICOS conducted an international inter-comparison of ocean pCO₂ instruments including direct air–water equilibration systems, membrane-based flow-through instruments, submersible sensors, and buoy-mounted systems. They were tested in a tank facility using natural North Sea water, where temperature and pCO₂ were systematically varied. Instruments were compared against an inter-comparison reference pCO2 during stable conditions. The study does not recommend specific sensors but results indicate that direct air–water equilibration is generally more consistent and less influenced by external factors than membrane-based or photometric methods. Missing or uncalibrated temperature measurements were identified as a major source of uncertainty.