VHF Wind-Profiler

For more information about VHF Wind-Profiler and data, please, contact Dr. Wayne Hocking.

The Windprofiler is an instrument for measuring wind speeds and direction as a function of height from altitudes of 400m to about 14 km, with a temporal resolution of minutes. It operates night and day throughout the year. It was installed by Mardoc Inc. in 2007, and has operated continuously since then. It comprises a large number of Yagi antennas coupled together to make an equivalent radar dish of about 60m diameter Its operating frequency is 52 MHz, and the radar beam can be steered to different angles in the sky, making it very versatile. It can also make studies of structures in the mesosphere in the summer.

For measurement of winds, the primary implementation is via the Doppler method. A pulse of radio-waves is transmitted, which strikes a moving target – in this case the target is patches of turbulence in the air. This causes a small shift in frequency, as illustrated in Fig. 1.  The shift is exaggerated in Fig. 1 – in reality the frequency is less than 1 part in 107.

By pointing the radar beam to different regions of the sky, and combining the information (see Fig. 2), the total wind vectors from  400m altitude to typically 14 km altitude can be found at typically 500m steps. Other techniques are used for applications like measuring turbulence and backscattered power – these are not discussed here.

Fig. 3. A wind-field graph produced from windprofiler data showing a mid-tropospheric jet.Other types of phenomena are evident at different times.

Fig. 3 shows a typical wind field measured by the radar. The small arrows are colour-coded according to wind speed, and also have lengths proportional to the wind speed. Time is shown on the abscissa, and altitude on the ordinate. Wind direction is indicated by the direction of the arrow – upward means toward the north, horizontal to the right means toward the east. In this case a strong jet can be seen building up and maximizing at 0300 on Feb 25, and 6 km altitude. The  radar can also measure turbulence strengths, backscattered strength signal strengths and tropopause heights.

 With these capabilities, the radar can be used to study many types of dynamical events in the atmosphere, including movement of frontal systems, wave production, turbulence variability, and long-term dynamical changes.  It is therefore well suited for studies of severe weather, weather forecasting and climate change. It can also measure the dynamics of events in the mesosphere at 80-95 km altitude, including studies of the very cold temperatures at those heights. This has implications for sub-orbital flight.