The {ATTO} Micrometeorological Intercomparison Experiment ({ATMIX})

A central constituent of the ATTO project is the deployment of an array of sonic anemometers to measure vertical profiles of means and second-order moments of the wind velocity vector. The two instruments used are the Campbell Scientific Instruments CSAT-3B and the Thies Ultrasonic Anemometer 3D. The accuracy of the vertical profiles of turbulent quantities critically depensds on an absence of bias between the measurement levels; however, dedicated intercomparisons of the sonic anemometers used in ATTO have not been previously performed. The main objective of the experiment was to check how close the sonic anemometers designated to be installed respond to the same atmospheric conditions, and to develop confidence in interpreting the measured data.