A networked two-dimensional sonic anemometer system for the measurement ofair velocity in greenhouses

The experimental study of air movement induced by natural ventilation in gr eenhouses requires a system to measure the air velocity field. A networked, two-dimensional sonic anemometer system was developed for simultaneous mea surement of the instantaneous air speed and direction at 12 locations. The system performance was tested and validated against a mass flow controller and a commercial, three-dimensional, ultrasonic anemometer. The sonic anemo meter system was then tested in greenhouse conditions. It showed that the h igh resolution, stability, proper frequency response and low cost of the sy stem were well adapted for the study of the air velocity field in greenhous es. (C) 1999 Silsoe Research Institute.