DOI: 10.14466/CefasDataHub.183

Description

A 4H JENA Ferrybox system runs continuously on RV Cefas Endeavour during all surveys where appropriate since 2010, generating data across the North Sea, Irish Sea, and English Channel at a resolution of one measurement per minute. A continuous inflow is taken from a dedicated inlet and pump at approximately 4m under the waterline. Key parameters measured include sea surface temperature (SST), through a hull mounted temperature probe, salinity (SAL), chlorophyll fluorometry (FLUORS), turbidity (FTU), and Photosynthetically Active Radiation (PAR). Other parameters recorded include meteorological variables, oxygen concentrations, and measures of photosynthetic activity. New data is added annually.

Water passes through the hull inlet while Endeavour is underway, then enters a circuit which contains other instruments approximately three minutes later. Data is autonomously recorded by the Ferrybox system, by taking an average of sensors readings over a minute, and stored on the Ferrybox computer on board Cefas Endeavour. Data is transferred to central network drives upon the ships return to shore, and is backed up by an emailer module every 10 minutes while the ship is underway.

QA is completed on shore using a custom R script. GPS data is checked to remove errors, including automatic checks of speed, course, and location. A correction for flow lag is applied to sensors within the ferrybox pipework, and data recorded during acid washes and where flow rates were too high or low is flagged. All variables are checked for reasonable ranges and rates of change. Data is validated by comparisons against discrete samples in the case of salinity, and for temperature and fluorescence though comparison between different instruments measuring the same parameter (eg. hull temperature probe and in-circuit seabird temperature sensor). In-house calibrations are also used to correct for instrument drift. Suspended particulate matter is derived from turbidity (FTU) values using the relationship between discrete samples and turbidity measurements throughout the ferrybox series. Chlorophyll is derived by survey using the relationship between fluorescence and discrete samples taken, for surveys where no discrete sample is taken a generic relationship is used.

Only data which has passed all quality control checks is included in this product. This product includes data at both qc_level 2 and 3

qc_level 2 is where all of the above checks have been done, but offsets / corrections based on external reference material have not been applied.

At qc_level 3 where these corrections have been applied.

Contributors

Hull, Tom / Collingridge, Kate / Greenwood, Naomi / Lake, Izzy / Salian, Amisha / Haigh, Eleanor / Visinand, Camille / Taylor, Michael

Subject

Water column temperature and salinity / Temperature of the water column / Salinity of the water column

Start Date

01/01/2010

End Date

Year Published

2025

Version

1

Citation

Hull et al. (2025). Underway (Ferrybox) data collected in North West European Shelf waters from 2010 onwards. Cefas, UK. V1. doi: https://doi.org/10.14466/CefasDataHub.183

Rights List

Open Government Licence

DOI

10.14466/CefasDataHub.183