Measuring wind patterns

On hearing the word, “radar”, we usually think of speed controls or air traffic control systems. In fact, there are many kinds of radar and applications thereof.

At Punta Galea in Getxo the Climatology and Meteorology Office of the Basque Government has installed a very special kind of radar: a radar that indicates the patterns of winds; wind patterns at up to 3,000 metres altitude indicating its direction and speed. This is what is special about the radar at Punta Galea.

In normal operation mode, the average wind patterns are obtained every 25 minutes and, moreover, the temperature is measured every 30 minutes. In order to obtain data about winds, the radar sends microwave pulses towards the sky in five directions by means of a multidirectional broadcasting aerial. One of these microwave beams is directed vertically, to the zenith; the other four towards the four cardinal points. Small variations in the atmosphere produce echoes and some of the pulses are reflected back to the radar antenna, where they are detected. The differences in frequency between the waves received and the waves emitted are processed and analysed by the computer and we obtain a representation of the wind pattern with its speed and direction at different altitudes. The interpretation of these results is the job of the researchers and technicians.

Normally wind data is obtained up to 3,000 metres altitude but this altitude varies according to atmospheric conditions. The temperature, on the other hand, measured combining the radar echoes with the emission of acoustic signals, has a lower limit, between 700 and 1,000 metres altitude.

All this data is received both in the Climatology and Meteorology Office and in the Atmosphere Environment Group at the School of Engineering on the Bilbao campus of the University of the Basque Country. Amongst the studies carried out by this research group are those relating to the presence of high-altitude ozone pockets above the Bilbao area, in concentrations that could not be due, in principle, to local emissions. Combining the data obtained from the wind pattern radar device with meteorological models for studying the conditions of ozone movement and direction models, it has been possible to demonstrate the transport of ozone over long distances. Thus, it has been confirmed that, in certain meteorological conditions, the ozone registered over the Basque Country, apart from being produced locally, may come from two other sources: one directly from Britanny and the other from the Ebro river valley, to the south, after passing over the south-west of France and Tarragona respectively, and picking up more ozone precursors.

It should be remembered that ozone is fundamental to life when it is at higher levels of the atmosphere but is dangerous to the health when found at lower levels. This is why it is important to know its patterns of movement and transport.