Axes alignment

Some Gill Instruments sonic anemometers allow you to output wind components in two configurations: AXIS or SPAR. In the AXIS configuration, the u horizontal component is aligned with one transducer pair, while in the SPAR configuration it is aligned with the North spar, which is identified either by an N or a notch on the instrument body. The difference between the two configurations is a 30 degree yaw offset (refer to the anemometer manual for more details). If your sonic anemometer does not have an AXIS/SPAR configuration option, just select "N/A" (not applicable).

See also: Adjusting the anemometer coordinate system.