What is an ultrasonic anemometer?

An ultrasonic anemometer measures wind speed and direction by transmitting sound pulses between fixed transducers and calculating how the wind affects their travel time. Because there are no rotating cups, vanes or bearings, ultrasonic anemometers provide reliable, low-maintenance wind measurement in demanding environments. Gill has been designing and manufacturing ultrasonic wind sensors for more than 40 years, supporting applications from meteorology and aviation to marine and industrial automation.

What is inside one

There are no bearings, no cups and nothing that turns. An ultrasonic anemometer is a fixed structure holding two or three pairs of transducers, each of which can both transmit and receive a short pulse of sound. The instrument fires pulses along each path in both directions, times them, and derives the wind from the difference.

Because the measurement is a timing calculation rather than a mechanical response, there is no starting threshold to overcome and no inertia to settle. A Gill 2-axis sensor resolves to 0.01 m/s and starts measuring at 0.01 m/s.

Two-axis or three-axis

The number of transducer paths sets what the instrument can see. This is the first fork in any specification.

Head design matters as much as axis count. An open head, as used on the WindObserver range, holds accuracy better as the vertical flow angle increases and supports the highest wind speeds. A reflector head, as used on WindSonic and WindUltra, is more compact and lower cost.

What Gill makes

The honest limit

Ultrasonic measurement removes wear, not physics. A 2-axis sensor cannot report a vertical component or turbulence, however good it is. Intrinsically safe certification exists only on the WindObserver IS, so an ultrasonic sensor is not automatically suitable for a hazardous area. And siting still governs the result: an instrument in the wake of a mast or a superstructure will report that wake accurately.