The Porcupine Abyssal Plain fixed-point sustained observatory (PAP-SO): variations and trends from the Northeast Atlantic fixed-point time-series

The Porcupine Abyssal Plainsustained observatory(PAP-SO) in the Northeast Atlantic (49°N 16.5°W; 4800 m) is the longest running open-ocean multidisciplinary observatoryin the oceans around Europe. The site has produced high-resolution datasets integrating environmental and ecologically relevant variables from the surface to the seabedfor >20 years. Since 2002, a full-depth mooring has been in place with autonomous sensors measuring temperature, salinity, chlorophyll-a fluorescence, nitrate, and pCO2. These complement ongoing mesopelagic and seabedobservations on downward particle flux and benthic ecosystem structure and function. With national and European funding, the observatoryinfrastructure has been advanced steadily, with the latest development in 2010 involving collaboration between the UK's Meteorological Office and Natural Environment Research Council. This resulted in the first simultaneous atmospheric and ocean datasets at the site. All PAP-SO datasets are open access in near real time through websites and as quality-controlled datasets for a range of remote users using ftpsites and uploaded daily to MyOcean and the global telecommunications systemfor use in modelling activities. The combined datasets capture short-term variation (daily–seasonal), longer term trends (climate-driven), and episodic events (e.g. spring-bloomevents), and the data contribute to the Europe-wide move towards good environmental statusof our seas, driven by the EU's Marine Strategy Framework Directive(http://ec.europa.eu/environment/water/marine).