Post-recovery ocean glider data from Seagliders deployed in the North Sea during the AlterEco project, November 2017-April 2019 (version 2).

As part of the Alternative Framework to Assess Marine Ecosystem Functioning in Shelf Seas (AlterECO) project (NERC grant reference NE/P013902/1), Seagliders (SG537, SG620, SG510, SG579, SG602 and SG550) were deployed in a physically dynamic region of the North Sea, known to undergo seasonal oxygen depletion, between November 2017 and April 2019. These deployments are part of an 18-month observational programme using marine autonomous vehicles. During each deployment the gliders tracked repeat North-South or East-West transects close to Dogger Bank. Each glider carried a standard CTD package measuring temperature and water conductivity (salinity) and an oxygen optode sensor with additional sensors such as downwelling PAR and optical sensors for chlorophyll fluorescence and backscatter. Nitrate and phosphate sensors were also included, and these data will be available separately. The deployments provided high resolution measurements of key hydrographical and biogeochemical parameters. In the previous version of the dataset, there were errors found in the positional record for deployment AE3 SG510. This was due to a bug in the processing routines when working with upcast only dives. This has been corrected in this version of the data where the values have been filled with the actual GPS fixes (single points per dive). During the 3-year programme and by developing and implementing a novel monitoring framework, AlterEco aims to deliver an improved spatio-temporal understanding of shelf sea function and provide measurements of critical indicators of marine ecosystem health over seasonal timescales.