中国海洋大学的一个研究组开发并测试了一种移动激光雷达（lidar，即激光探测及测距系统）站，它可以准确地实时测量大范围区域的风速和风向——这项应用对于航空安全、天气预报和体育都有用处。

研究人员在美国光学学会7月1日出版的《光学快报》（Optics Letters）上描述说，这种移动激光雷达站可以更准确地测量风场，这可能帮助世界级运动员在国际比赛中竞技，例如奥林匹克运动会。中国海洋大学位于青岛，而青岛将承办第29届奥林匹克运动会和北京2008年残奥会的帆船比赛。该技术目前正在为这一活动进行测试。

“即便是在小型帆船赛场，风也不均匀，”领导这项研究的中国海洋大学海洋遥感教育部重点实验室的刘智深教授说。“如果运动员拥有最准确的信息帮助他们捕捉到风，那么他们就可能发挥出最高水平。”

在奥运会帆船比赛中，单个参赛者或者运动队驾驶不同级别的帆船在一条赛道上进行计时赛。比赛要求他们在逆风、顺风以及二者之间的任何情况下驾船行驶。他们的最终时间成绩取决于许多因素，包括船的设计、船员的技能、赛道困难程度以及海流。然而，或许最重要的因素是运动员能够多么成功地利用风把帆张满。

由于风的速度和方向不断变化，运动员和教练希望在比赛开始时拥有最准确的信息。在多云和下雨的时候，标准的气象工具——多普勒雷达可以准确地提供风场信息。然而，当没有云的时候，多普勒雷达就无效了。晴天的最佳风数据来自海洋浮标和陆地观测站，它们利用风杯和超声波风速计测量风速。

在今年夏天将要进行比赛的青岛帆船航行区只有4个浮标、1艘船和1座塔用于测量大约10平方千米的比赛区内的海面风。

刘智深和他的激光雷达研究组一直在研究一种光学遥感技术，称为多普勒激光雷达。他们把它用于天气和环境研究。激光雷达通过被大气气溶胶或分子散射的激光束运作。多普勒激光雷达利用了一个现象，即当这些气溶胶或分子在风中运动的时候，散射的激光的频率会发生变化——这与汽车接近你的时候比驶离你的时候音调更高是一样的。

刘智深说，多普勒激光雷达的优点是它可以迅速地对大片区域进行采样，能比单独使用浮标提供更精细的风图。他和他的研究组已经开发了一辆激光雷达巴士，它可以方便地把设备运送到实验区域。

去年，他们成功地在2007年青岛国际帆船赛上测试了这辆新的巴士。他们把这辆巴士开到了比赛区域附近的海滨，并对海面进行了水平扫描，进行实时测量，然后每隔10分钟把数据上传到当地气象站。他们打算在即将到来的奥运会和残奥会赛事上也采取类似的措施。

New Technology May Help Olympic Sailing; Doppler Lidar More Accurately Shows Which Way the Wind Blows

A team of researchers at the Ocean University of China has developed and tested a mobile lidar (light detection and ranging) station that can accurately measure wind speed and direction over large areas in real time — an application useful for aviation safety, weather forecasting and sports.

As described in the July 1 issue of the journal Optics Letters, published by the Optical Society, the mobile lidar station can measure wind fields more accurately, which could help world-class athletes compete in international competitions, such as the Olympics. Ocean University is in Qingdao, which is hosting the sailing competitions of the XXIX Olympic Games and the Beijing 2008 Paralympic Games, and this technique is being tested in conjunction with the event.

“Wind is non-uniform even in a small sailing field,” says Professor Zhi-Shen Liu of the Key Laboratory of Ocean Remote Sensing, Ministry of Education of China, Ocean University of China, who led the research. “Athletes could maximize their performances if they have the most accurate information to help them capture the wind.”

In Olympic sailing, individual competitors or teams of athletes sail various classes of sailboats in timed trials over a single course. The contest requires them to navigate upwind, downwind and everything in between. Their final time depends on numerous factors, including the boat design, the skill of the sailors, course difficulty and ocean currents. Perhaps the most important factor, though, is how well the athletes can harness the wind that fills their sails.

Because wind constantly changes speed and direction, athletes and coaches hope to have the best information at the start of a run. On cloudy, rainy days, the standard meteorological tool of Doppler radar can accurately provide wind field information. When no clouds are present, however, Doppler radar is ineffective. The best wind data on clear days comes from ocean buoys and land stations that use wind cups and ultrasonic anemometers to measure wind speed.

In the Qingdao sailing area, where this summer’s competitions will take place, only four buoys, one boat and one tower are available to measure sea surface winds within a competition area of approximately 10 square kilometers.

Liu and his lidar group, composed of research scientists and graduate students, have been working with an optical remote sensing technology called Doppler lidar, which they are applying for 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, says 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, they 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.

The research was funded by the National Natural Science Foundation of China, the Key Laboratory of Ocean Remote Sensing, the Ministry of Education of China and the China Meteorological Administration (CMA).

Paper: “A high spatial and temporal resolution mobile incoherent Doppler lidar for sea surface wind measurements” by Zhi-Shen Liu et al., Optics Letters, Vol. 33, No. 13, July 1, 2008 p. 1485-1487