To obtain the turbulent fluxes the eddy-correlation technique is used. The measuring system is based on a 3D ultrasonic anemometer in combination with a fast infrared gas analyser placed on the top of a 23.4 m tower. A full description of the system is given by Moncrieff et al. (1997) and Aubinet et al. (2000). In the first setup (from fall 1996 till june 2001) A Gill R2 was used in combination with a Li-Cor LI-6262 and a Campbell Krypton hygrometer KH2O. Raw data are stored at 10 Hz using a HP Palmtop PC and PCMCIA cards.

Since july 2001 a Gill windmaster Pro is installed in combination with an open path Li-Cor LI-7500.


To determine net radiation the four components of the radiation balance are measured separately. Incoming and reflected short wave radiation are measured with two pyranometers. The long wave components are measured by pyrgeometers, with the sensor for the incoming long wave radiation being ventilated. At the top of the scaffolding tower (23.4 m) standard meteorological measurements of precipitation, horizontal wind speed, wind direction, relative humidity and air temperature are made. Soil heat flux is measured using a heat flux sensor just under the litter layer. Soil moisture and temperature is measured in two profiles at five depths. Additionally profiles (five levels) are measured of CO2 and H2O concentrations as well as wind speed and temperature.

List of instrumentation

Variable Instrument Manufacturer Type Height in m above ground
Turbulence components Sonic anemometer Gill Instruments Windmaster Pro 26.0
Virtual temperature Sonic anemometer Gill Instruments Windmaster Pro 26.0
CO2/Specific humidity fluctuations Infra-red gas analyser LI-COR LI-7500 26.0
Incoming/outgoing short wave radiation Pyranometer Kipp&Zonen CM21 21.9
Incoming/outgoing long wave radiation Pyrgeometer Kipp&Zonen CG1 21.9
Temperature long wave radiation sensors Platinum resistance Kipp&Zonen PT100 21.9
Reflected photosynthetically active radiation Quantum sensor LI-COR LI-190SZ 21.9
Direct photosynthetically active radiation Quantum sensor Delta-T Devices BF-3 24.5
Diffuse photosynthetically active radiation Quantum sensor Delta-T Devices BF-3 24.5
Air temperature Platinum resistance Vaisala HMP35A 23.5, 7.5, 5.0
Air pressure Analog barometer Vaisala PTB101C 15.0
Relative humidity Capacitive sensor Vaisala HMP35A 23.5, 7.5, 5.0
Wind speed Cup anemometer Vector Instruments A101ML 24.4, 7.5, 5.0
Wind direction Wind vane Vector Instruments W200P 24.0
CO2/H2O-concentration IRGA PP systems CIRAS-SC 24.4, 7.5, 5.0, 2.5, 0.4
Precipitation Tipping bucket EML ARG100 23.8 (tower), 0.4 (open field)
Throughfall Tipping bucket IMAG-DLO - 1.0
Soil heat flux Thermopiles TNO-TPD PU43T -0.1
Soil moisture Frequency domain Campbell Scientific CS616 litter, -0.03, -0.20, -0.50, -1.0
Soil temperature Thermistor Campbell Scientific 107 litter, -0.03, -0.20, -0.50, -1.0
Bole temperature Thermistor Campbell Scientific 107 4.0
Groundwater level (filter depth)       -6.5, -4.8

Aubinet M., Grelle A., Ibrom A., Rannik �., Moncrieff J., Foken T., Kowalski A.S., Martin P.H., Berbigier P., Bernhofer Ch., Clement R., Elbers J.A., Granier A., Gr�nwald T., Morgenstern K., Pilegaard K., Rebmann C. , Snijders W., Valentini R., Vesala T. Estimates of the Annual Net Carbon and Water Exchange of Forests: the EUROFLUX Methodology. Adv. Ecol. Research, 30 (2000), 113-175.

Moncrieff, J.B., J.A. Elbers, & others, 1997. A system to measure surface fluxes of momentum, sensible heat, water vapour and carbon dioxide. Journal of Hydrology 188-189/89-611, special issue on HAPEX-Sahel, 1997, Elsevier Science.