Details

• utilises a sonic anemometer and a sampling system which minimises flow disturbances
• has low power consumption and is fully weatherproof
• is able to store raw data to obtain additional information concerning the turbulent fluxes e.g. 2nd, 3rd, 4th moments, spectra etc.
• uses research-grade processing, analysis and correction procedures
• has been tested in a number of international surface flux experiments including HAPEX-Sahel, BOREAS and ABRACOS
• is a standard in the first flux network (EuroFlux)
• currently in use in Europe, S.E. Asia, Brazil, Australia and USA

The system uses commercially-available instrumentation: a 3-axis sonic anemometer (Gill A1012R3) and an infra-red gas analyser (LI-COR 7000). Air to be sampled is brought to the optical bench by being ducted down a sampling tube from a point near the sonic anemometer. The system is controlled by specially-written software which calculates the surface fluxes of momentum, sensible and latent heat and carbon dioxide and displays them in real time on a PC screen.

Up to five additional analogue instruments can be sampled at up to 10 Hz and digitised by the sonic anemometer. The system consumes relatively little power and can operate from appropriate solar cells or rechargeable batteries in addition to line power (typical power consumption is about 50 Watts). CO₂ calibration of the gas analyser can be done automatically. The system requires minimal maintenance and is weather insensitive. It can be operated for the routine collection of surface flux data for extended periods.