CSAT3 Three-dimensional Sonic Anemometer

The CSAT3 is a three-dimensional sonic anemometer. It measures wind speed and the speed of sound on three nonorthogonal axes. From these measurements, orthogonal wind speed and sonic temperature can be computed.
The CSAT is used in eddy covariance applications to measure the turbulent fluctuations of horizontal and vertical wind. From the turbulent wind fluctuations, momentum flux and friction velocity can be calculated. The CSAT3 can also be used to measure average horizontal wind speed and direction.
Features
Measures turbulent fluctuations of horizontal and vertical wind
Measures wind speed and the speed of sound on three nonorthogonal axes.
Provides upper and lower transducers that are separated by a vertical distance of 10 cm and are oriented 60 degrees from horizontal.
Typically used with fine wire thermocouples and LI7500 (or KH20) in Eddy covariance systems
No moving parts
Specifications
Measurements
Outputs: ux, uy, uz, c (ux, uy, uz are wind components referenced to the anemometer axes; c is speed of sound)
Speed of Sound: Determined from three acoustic paths; corrected for crosswind effects
Measurement Rate: programmable from 1 to 60 Hz, instantaneous measurements; two over-sampled modes are block averaged to either 20 Hz or 10 Hz
Measurement Resolution: ux, uy is 1 mms rms; uz is 0.5 mms rms; c is 15 mms (0.025°C) rms; values are for instantaneous measurements made on a constant signal; noise is not affected by sample rate
Accuracy (assumes -30° to +50°C range; wind speeds