employing an EC system and meteorological instrumentation.Data were recorded steadily throughout the whole study period with the exception of july to september 201.when EC instrumentation was not operating,and only meteorological data were recorded
The EC system was located on a tower 3.5 m above surface.This system consists of a three-dimensional sonic anemometer,measuring wind velocity and sonic temperature,and an open-path IRGA measuring CO2 and water vapour concentration,with a sampling frequency of 10 Hz.