Observation series

COAST-HF Iroise

High frequency hydrological monitoring

The “COAST-HF-Iroise” high-frequency hydrological monitoring system has been operated since 2000 by IUEM/Ifremer to characterise, at high frequency (sub-hourly), the general state of the water masses of the Brest Bay – Mer d’Iroise coastal system. It aims to observe and understand the evolution of the environment in response to climate change in terms of extreme and episodic events. It has been carried out since 2000 using an instrumented and automated buoy managed by the IUEM and Ifremer. It is the local version of the national observation service COAST-HF (Coastal ocean observing system – High frequency) labelled by INSU/CNRS, which is made up of 14 observation stations distributed over the whole of the French coastline. It is an integral part of the ILICO coastal research infrastructure.

Partners

The site

COAST-HF-Iroise monitoring is implemented at 200 m from the Ste-Anne-du-Portzic observation site (48°21’48 N, 4°33’33 W), at the level of the entrance gully of the Brest roadstead, at the interface with the Iroise Sea.

Monitoring

Sampling is carried out using the MAREL-Iroise buoy anchored at a fixed point and equipped with sensors placed at a depth of 2.5 m. It is an autonomous buoy which allows measurements every 20 minutes without intervention for 3 months thanks to an anti-fouling system based on the chlorination of the sea water.
A multiparameter
probe (MP6-NKE) records 5 essential hydrological parameters such as conductivity, temperature, dissolved oxygen, fluorescence and turbidity every 20 minutes. Additional sensors such as the Seafet and a CARIOCA complete the recordings for pH and dissolved CO2 every hour. An aerial weather station also provides access to wind, pressure and light (PAR) parameters.
The whole system is managed in such a way as to ensure the metrological control of the sensors and the quality of the data.