Pride of Bilbao FerryBox 2005 - an overview of the data obtained and improvements in procedures

The collection of high quality, long term data from diverse environments is required if the interplay of the complex factors affecting phytoplankton bloom development is to be investigated. With this in mind the English Channel and Bay of Biscay between Portsmouth and Bilbao has been intensively monitored starting in 2002. In 2005 the ‘FerryBox’ suite of sensors measured temperature, salinity, fluorescence, oxygen and turbidity. The data are merged with position and can be viewed in real time at http://www.noc.soton.ac.uk/ops. The ferry travels between Portsmouth and Bilbao completing a round trip every 3 days; measurements in water pumped in from 5 metres depth provide data which are collected every second. In 2005 the ‘FerryBox’ methods were improved to reduce the affects of bio fouling on the sensors; the sensors were systematically cleaned weekly and sensor calibrations made from samples collected during monthly ferry crossings. These showed that the fluorescence and oxygen sensors were stable and a high quality dataset was produced. Calibration of the fluorescence sensor was monitored using extracted chlorophyll suspended in solid Perspex blocks. The ‘FerryBox’ dataset has been mapped against time and latitude to show the occurrence of phytoplankton blooms, using fluorescence, along with calculations of oxygen anomaly. Such continuous monitoring allows us to pinpoint the timings of phytoplankton bloom initiation and duration. The detailed data from the FerryBox allows the occurrence of these blooms to be correlated with other changes in the oceanic system, such as tidal energy, light and fresh water run off. The methods used to process the data from the initial raw 1Hz ASCII files through to the quality controlled 5 minute set are documented together with the post processing resolution of system faults that caused errors in the measured salinity. The quality controlled data are archived as 5 minute averages and are held by the British Oceanographic Data Centre (BODC).