SOMLIT-SOGIR time series (French Research Infrastructure ILICO): long-term core parameter monitoring in the Gironde Estuary

The SOMLIT-SOGIR time-series data characterize the hydrology of the Gironde Estuary ecosystem, located in the South-western France and flowing into the Bay of Biscay. Monthly-like measurements have been undertaken since 1997 by the OASU and EPOC teams (Univ. Bordeaux/CNRS). The SOMLIT-SOGIR time series is a part of the French monitoring network SOMLIT (, labelled by the CNRS as a national Earth Science Observatory (Service National d’Observation : SNO). It aims to detect the long-term evolution of monitored ecosystems including both natural and anthropogenic forcings.
Implemented at three sites (PK 30: 45.06833°N, 0.63833°W; PK 52: 45.24667°N, 0.725°W; PK 86:  45.5167°N, 0.95°W), the SOMLIT-SOGIR time series is among the oldest long-term coastal observation time series of the French Research Infrastructure dedicated to coastal ocean observations (RI ILICO,
SOMLIT-SOGIR samples are collected at 1m below the water surface and 1m above the floor, at high and low tide, during slack water. Samples collected are analysed for 15 core parameters: water temperature and salinity, dissolved oxygen, pH, ammonia, nitrate, nitrite, phosphate, silicic acid, suspended particulate matter, particulate organic carbone, particulate nitrogen, chlorophyll a, delta15N and delta13C. CTD-PAR-profile is also performed at site PK86 during high tide.
The SOMLIT network quality management system is in line with the ISO/IEC 17025:2017 standard: “General requirements for the competence of testing and calibration laboratories”. Further information on standard operating procedures for sample collection and data acquisition are available at: For more information on the quality flagging scheme:


Chemical oceanography, Biological oceanography, Cross-discipline, Environment, Fisheries and aquaculture, Physical oceanography


Environmental time series, Hydrological and biogeochemical data, Coastal system trend and trajectory, Climate impact, Coastal ecology, Atlantic Ocean, Bay of Biscay, Gironde Estuary, ILICO, SOMLIT


45.65N, 45.033S, -0.583E, -1.083W


A SBE-19-V2 profiler is used for CTDPAR measurements. To guarantee best performances, the sensors return to the constructor every two years for calibration.


Alternative access to data

SOMLIT-SOGIR, PK30, Hydro time series 1997-2023
212 KoCSVQuality controlled data
SOMLIT-SOGIR, PK52, Hydro time series 1997-2023
209 KoCSVQuality controlled data
SOMLIT-SOGIR, PK86, Hydro time series 1997-2023
188 KoCSVQuality controlled data
SOMLIT-SOGIR, PK86, CTD time series 1997-2023
337 KoCSVQuality controlled data
How to cite
Savoye Nicolas, Sottolichio Aldo, Del amo Yolanda, Nowaczyk Antoine, Labourdette Nathalie, Costes Laurence, Mornet Line, Parra René, Lequeux Joséphine (2023). SOMLIT-SOGIR time series (French Research Infrastructure ILICO): long-term core parameter monitoring in the Gironde Estuary. SEANOE.

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