CE17007 GO-SHIP TransAtlantic Section A02

This survey took place in April-May 2017 on board the RV Celtic Explorer. The Marine Institute (MI) and National University of Ireland, Galway (NUIG) led an international partnership to complete the GO-SHIP A02 line. Onboard teams were from Canada, Germany, the UK, and the USA, and additional support from experts in Denmark and France. The A02 line runs from the margins of the Grand Banks, south of Newfoundland, to the shelf edge of the Celtic Sea off southern Ireland. Continuous underway measurements included surface seawater conductivity (salinity), temperature and partial pressure of carbon dioxide (pCO2), sampled via a hull water intake hose, and water current measurements to ~600 m depth using a vessel mounted Acoustic Doppler Current Profiler (ADCP). At predefined stations along the cruise track, approximately 30 nautical miles apart in the open ocean, the ship’s CTD sensor package and bottle rosette was deployed. Fitted with a range of calibrated sensors that measure conductivity, temperature and depth (CTD), dissolved oxygen relative fluorescence (chlorophyll), water clarity and water current measurements, the CTD carousel was lowered to just above the ocean floor and then brought back to the surface in an operation that took up to five hours at the deepest stations of > 4.8 km below the ocean surface. Ship-based hydrography is essential for documenting ocean changes throughout the water column, especially for the deep ocean below 2 km (52% of global ocean volume not sampled by profiling floats). Ship based platforms are the only current way to achieve high quality spatial and vertical measurement resolution. GO-SHIP is the only program that provides coincident comprehensive high resolution and quality, full depth inventory of key physical, carbon and biogeochemical observations. These measurements can validate the new generation of autonomous sensors on floats, gliders and buoys. GO-SHIP provides a ship-based platform for sensor development and assessment. GO-SHIP delivers data to GEO, and supports the products produced by the Carbon Dioxide Information Analysis Centre (CDIAC) based in the USA and the Surface Ocean CO2 Atlas (SOCAT). Objectives As part of an international programme, this A02 survey section is designed to be multidisciplinary in nature; to monitor and assess the ocean climate of waters to the west of Ireland and across the Atlantic to Canada. This contributes to an important global decadal time-series dataset; along a section that has been surveyed in the past. The main objectives are to: 1. Understand and document the large-scale ocean water property distributions, their changes, and drivers of those changes 2. Address questions of how a future ocean that will increase in dissolved inorganic carbon, become more acidic and more stratified, and experience changes in circulation and ventilation processes due to global warming, altered water cycle and sea-ice will interact with natural ocean variability.