Beschreibung: Autonomous systems measuring the partial pressure of CO2 (pCO2) in surface waters on commercial carrier ships (Voluntary Observing Ship, VOS), which allows for high spatiotemporal data coverage, are a major component of the Ocean Thematic Centre (OTC) data stream. Currently, ICOS operates lines in the Atlantic, North Sea and the Baltic. All lines are determining pCO2 by measuring CO2 in air that has been equilibrated with seawater. As part of the European H2020 project RINGO (https://www.icos-ri.eu/ringo), we are evaluating the possibility of using VOS to expand the atmospheric network. We will provide technical solutions for three different settings and approaches, and assess the added value for the atmospheric observation network. Two systems are designed as stand-alone modules for continuous atmospheric CO2 and CH4 measurements, following the technological requirements defined by the ATC, and will be operated in the Baltic (high anthropogenic influence) and on a line between France and Brazil (clean marine air, large temperature and humidity gradient). A second approach is using the existing instrumentation for seawater measurements (North Atlantic), which we aim to improve in order to make these measurements usable for the atmospheric research community. This is an effort that connects the ocean research community with the Central Analytical Laboratories (CAL; testing an extended range of standard gases, providing flask sampling opportunity), the Atmospheric Thematic Centre (ATC; work on data streams that can be digested by the ATC system), and the modelling community (identifying useful sampling strategies). Here we present a status update of the ongoing work, which is a joined effort of the atmospheric and ocean community within ICOS and relying on the expertise of both fields.