The MOLIT (Mer Ouverte LITorale) measuring station developed and implemented by Ifremer (French Research Institute for Exploitation of the sea) is a moored buoy equipped with biological and physico-chemical sensors working in continuous and autonomous conditions. The system is located South of Brittany in the Vilaine Bay, one of the areas of the Atlantic coast most threatened by eutrophication.

The buoy was deployed during the period of primary productivity, from March to October from 2011 to 2017 and has been deployed throughout the year since March 2018.

The measuring station is equipped with high performance systems for seawater analysis and near real time data transmission. This station performs measurements at two levels : subsurface = LEVEL1 and bottom (1 m above the water-sediment interface) = LEVEL3. This system records with a high frequency resolution (one hour), the following parameters : sea temperature (TEMP), practical salinity (PSAL), dissolved oxygen (MASS DOXY), turbidity (TUR4) and fluorescence (FLU3). Some fluorescence data has been corrected and appears in the “fluorescence adjusted” parameter (FLU3 ADJUSTED). Dissolved oxygen measurements are compensated for temperature and salinity.

This system also records with a high frequency resolution (20 minutes), the following parameters : air temperature in dry bulb (DRYT), gust wind speed (GSPD), gust wind from direction relative true north (GDIR), horizontal wind speed (WSPD), wind from direction relative true north (WDIR), surface incoming photosynthetic active radiation (LGH4).

The data were qualified into several levels : 0-No QC performed, 1-Good data, 2-Probably good data, 3-Probably bad data, 4-Bad data, 5-Value changed, 7-Nominal value, 8-Interpolated value, 9-Missing value. The quality level is indicated in the data file in a column “QC” for each parameter. The information that led to the quality level are synthesized in an annual report qualification. Precision estimated of the complete data collection process is : temperature (±0.1°C), conductivity (±0.3mS/cm), in vivo fluorescence (±10%), turbidity (±10%), dissolved oxygen (0.2 mg/L).

The MOLIT station is a component of the national high frequency observing network COAST-HF (http://www.coast-hf.fr) from the ILICO research infrastructure (https://www.ir-ilico.fr).