Head or flow distortion correction

When the wind approaches with a considerable Angle of Attack (that is, from an angle other than horizontal), the frame of post-mounted anemometers (such as Gill R2, R3, WindMaster, or Metek USA-1) distorts the flow, resulting in less accurate wind measurements. Furthermore, the transducer poles create a self-sheltering effect that also affects the measurement. This second effect also occurs with yoke-style anemometers (Gill HS and Campbell® Scientific CSAT3). Several anemometer models use a firmware correction for these effects (referred to as “head correction,” “flow distortion correction,” or "Angle of Attack correction") and in some cases it can be turned on or off in the anemometer settings. Here you must specify whether the correction was applied in your anemometer(s) at the time data was collected.