Gary Archibald, Weathercaster

The series continues… and I hope that you have enjoyed the look at various weather/meteorological devices and instruments that help forecaster like myself, determine and collect valuable data that in turn tell the story about weather.

Next up in the series…a device used to measure wind properties…

A wind profiler is a type of weather observing equipment that uses radar or sound waves (SODAR) to detect the wind speed and direction at various elevations above the ground. Such data is very useful to meteorological and aviation interests.

A radar wind profiler installation

Doppler radar wind profilers operate using principles similar to those used by Doppler sodars, except that electromagnetic (EM) signals are used rather than acoustic signals to remotely sense winds aloft. In a typical implementation, the radar can sample along each of five beams: one is aimed vertically to measure vertical velocity, and four are tilted off vertical and oriented orthogonal to one another to measure the horizontal components of the air's motion. A UHF profiler includes subsystems to control the radar's transmitter, receiver, signal processing, and RASS ((Radio Acoustic Sounding System), if provided, as well as data telemetry and remote control.

The radar transmits an electromagnetic pulse along each of the antenna's pointing directions. The duration of the transmission determines the length of the pulse emitted by the antenna, which in turn corresponds to the volume of air illuminated (in electrical terms) by the radar beam. Small amounts of the transmitted energy are scattered back (referred to as backscattering) toward and received by the radar. Delays of fixed intervals are built into the data processing system so that the radar receives scattered energy from discrete altitudes, referred to as range gates. The Doppler frequency shift of the backscattered energy is determined, and then used to calculate the velocity of the air toward or away from the radar along each beam as a function of altitude.

Indeed, this device is unique to high level wind data collection and analysis… great stuff!

Next time: A look at DOPPLER RADAR systems.