Researchers at the Ocean University of China have developed and tested a mobile lidar (laser light detection and ranging) station that can accurately measure wind speed and direction over large areas in real time, which is useful for sports. Offering more accurate wind measurements, the new device can help world-class athletes compete in international competitions, such as the Olympics, in addition to its original role in aviation safety and weather forecasting.

The Ocean University of China is located in coastal Qingdao City, east China's Shandong Province, which is to host sailing competitions of this year's Olympic and Paralympic Games.

As for sailing, individual competitors or teams of athletes sail various classes of sailboats in timed trials over a single course. Sailors are required to navigate upwind, downwind and everything in between. The final time depends on numerous factors, such as boat design, skill of the sailors, course difficulty and ocean currents, but the most important factor is how well the athletes can harness the wind that fills their sails. Sailors and coaches all hope to have the best information at the start of a run as the wind changes speed and direction constantly.

On cloudy, rainy days, the standard meteorological tool, the Doppler radar, which uses the Doppler effect of returned echoes from targets to measure their radial velocity, can accurately provide wind field information. When no clouds are present, however, Doppler radar is ineffective. The best wind data on clear days come from ocean buoys and land stations that use wind cups and ultrasonic anemometers to measure wind speed.

In the Qingdao sailing area, however, only four buoys, one boat and one tower are available to measure sea surface winds within a competition area of approximately 10 square km.

"Wind is non-uniform even in a small sailing field," said Professor Liu Zhishen at the Key Laboratory of Ocean Remote Sensing of the Ocean University of China. "Sailors could maximize their performances if they have the most accurate information to help them capture the wind."

Liu and his research team have been working with an optical remote sensing technology called Doppler lidar, which they are applying to weather and environmental research. Lidar works by scattering laser beams off atmospheric aerosols or molecules. Doppler lidar takes advantage of the fact that when these aerosols or molecules are moving in the wind, the scattered laser light changes frequency-the same way an approaching car has a higher pitched sound than a car driving away.

The advantage of Doppler lidar, according to Liu, is that it can quickly sample a large area, providing a much finer map of winds than buoys alone. He and his group have developed a lidar bus, which can move equipment to the experiment field conveniently.

Last year, the researchers successfully tested their new bus at the 2007 Qingdao International Regatta sailing event. They moved the bus to the seashore near the sailing field, and made a horizontal scan over the sea surface, making the measurement in real time and then uploading the data to the local meteorological station every 10 minutes. They envision a similar effort in the upcoming Olympic and Paralympic games.