This special issue will cover scientific advances and R&D achievements from the Copernicus Marine Environment Monitoring Service (CMEMS) during its first phase of implementation (2015-2018). The CMEMS is the operational marine service of the EU Copernicus Programme, which establishes a unique European capacity for Earth observation and monitoring. CMEMS provides regular and systematic reference information on the physical state, variability and dynamics of the ocean and marine ecosystems for the global ocean and the European regional seas. This capacity encompasses the description of the current situation (analysis), the variability on different spatial and temporal scales, the prediction of the situation a few days ahead (forecast), and the provision of consistent retrospective data records for recent years (reanalyses and reprocessed datasets). CMEMS provides a sustainable response to European user needs in four areas of benefits: (i) maritime safety; (ii) marine resources; (iii) coastal and marine environment; (iv) weather, seasonal forecast and climate.

This special issue is open to all submissions within its scope. Contributions will include papers from the (1) CMEMS production centres for both satellite and in situ observations and modelling/assimilation, (2) CMEMS-funded R&D service evolution projects (e.g. http://marine.copernicus.eu/science-learning/service-evolution/rd-projects-funded-cmems/), and (3) CMEMS cross-cutting scientific coordination activities on multi-year products and ocean state assessment and product quality evaluation.