A wind profiler is a type of equipment used to observe upper-air wind speed/direction. These units emit radio waves, which are scattered as a result of turbulent atmospheric density. The frequency of returning waves is shifted due to the movement of the scattering air mass (i.e., the Doppler effect), allowing analysis to determine wind direction/speed. Radio waves are radiated upward in five directions, allowing observation of wind components on a three-dimensional basis.

  The Japan Meteorological Agency (JMA) has been conducting wind profiler observation since April 2001. At present, a nationwide network of 33 wind profilers is in operation. Observation data from the relevant sites are collected in real time at the central monitoring station of JMA headquarters for prediction (supporting the provision of precise weather forecasts) and other purposes. This comprehensive system of instruments and processing servers is collectively referred to as the Local Weather Monitoring System, or WINDAS (the WInd profiler Network and Data Acquisition System).

Wind profiler observation stations

  Wind profilers are used to observe upper-air wind at altitude intervals of 300 m every 10 minutes. Wind direction/speed is observed up to altitudes of 12 km from the surface (depending on weather conditions).

  Wind profilers observe the movement of raindrops, which scatter radio waves more than atmospheric turbulence. Wind direction/speed can also be observed as raindrops are blown by wind. The vertical speed of raindrops is taken as their falling velocity.

  Dry atmospheric conditions make it difficult to obtain observation data from wind profilers because the accompanying turbulent density tends to be low. In addition, observation data obtained using wind profilers are checked in quality control processes. Blank areas on data charts correspond to dry-air regions or data removal in quality control.