Limnological data of Lake Champs-sur-Marne (France) – Continuous monitoring of water column and meteorological variables over year 2021.

Description These data sets are related to high frequency measurements carried out at Lake Champs-sur-Marne (France) during the year 2021, from March 3 (0:00) to December 31 (12:00). The time reference is UTC. Lake Champs-sur-Marne is an experimental site operated by the Laboratoire Eau, Environnement et Systèmes Urbains (LEESU) of the Ecole nationale des ponts et chaussées | Institut Polytechnique de Paris (contact person: Dr. Brigitte Vinçon-Leite at [e-mail]). For more than one decade, it has been the study site of various research projects. The lake is a former sand pit located in the greater Paris (France). The surface area of the lake is 10 ha and the maximum width is about 540 m. The average and maximum depths are 3 m and 4 m respectively. A monitoring system (named Prol'Eau) is installed in the center part of the lake to survey the water quality, including algae dynamics. This system consists of an instrumented, autonomous buoy with a cleaning device. It is equipped with underwater sensors to monitor biological and physico-chemical variables and with a meteorological station located on the buoy top. A winch is used to perform a survey of the water column at 5 depths (0.5, 1.0, 1.5, 2.0, 2.5 m), scheduled every 6 hours. When the wind speed is too high, the profiling device stops and the time step of data collection increases. A longer time step can also occur when the battery level is low, in order to reduce the power requirements. Prol'Eau’s data for 2021 can be found in the file 'S41_HF_WQ.csv'. For each measurement depth, the following variables are recorded: Date (dd/mm/yyyy hh:mm:ss - 'date_time') Water temperature (°C) Oxygen concentration (mg L-1) Chlorophyll (µg L-1) Yellow substances (Relative fluorescence units RFU ) Specific conductivity at 25 °C (µS cm-1) In the file, the variables are displayed according to the 5 measurement depths ('t_depth m','do_depth m','Chla_depth m','YS_depth m','CondSpec_depth m'). The structure of the file is as follows: 1st column: date_time (dd/mm/yyyy HH:MM:SS); 2nd to 6th columns : variables at 0.5m 7th to 11th columns : variables at 1.0m 12th to 16th columns : variables at 1.5m 17th to 21th columns : variables at 2.0m 22th to 26th columns : variables at 2.5m The meteorological measurements are taken at 2 m above the water surface every hour. 2021 data can be found in the file 'S41_HF_met.csv'. The following variables are recorded: Date (dd/mm/yyyy hh:mm:ss - 'Date_Hour') Air temperature (°C - 'airtemp_C') Relative humidity (% - 'RH_percent') Wind direction (° - 'Win_Dir_°') Solar radiation (W m-2 - 'SR_w_m2') Precipitation (mm - 'precip_mm') The datasets are used for various research topics: to drive and calibrate a coupled hydrodynamic-ecological model; to study extreme events in shallow urban lakes; for inter-laboratory studies on algal dynamics in shallow lakes; to provide limnological meta-data for other research projects, and for operational applications by providing information to lake managers on bathing conditions (e.g., Baln'Eau - https://balneau-leesu-rec.enpc.fr/#!/dashboard).