PORTLAND, Ore. Doppler radar is routinely used to detect weather conditions, especially rain clouds, around a horizontally rotating beacon. Unfortunately, the most reliable means of adding the third dimension--vertical--to determine the height of cloud formations and weather conditions at different altitudes, remains the weather balloon.
Researchers at the Ecole Polytechnique Federale de Lausanne (EPFL, Switzerland) claim to have made the weather balloon obsolete with a vertically projecting lidar (light detection and ranging) system that scans the sky instantaneously up to 10 kilometers (6.2 miles).
What is claimed as the world''s first installation of a 3-D lidar-based weather-forecasting measurement system was inaugurated this week (Aug. 26) by the Swiss National Science Foundation and MeteoSwiss, Switzerland''s national weather service (Payerne).
Firing vertically 30 times a second, the lidar-based system is said to provide continuous data on atmospheric conditions. Before the lidar system was installed, weather balloons had to be launched several times a day to take readings that required minutes to hours to achieve their assigned altitudes.
Unlike radar systems that send out radio waves horizontally, the lidar system transmits a powerful vertical laser beam. Reflections from the laser beam then echo back to Earth, where they are sensed and interpreted to provide instantaneous measurements of both temperature and humidity.
Lidars often require frequent calibration in order to maintain their accuracy, according to EPFL, but the new system installed at MeteoSwiss is said to be self-calibrating. In tests, the Swiss lidar system required no manual calibration steps even after several months of trials.
The forecasting tool was added to its the organization's Center for Technical Measurements and will be added to its Baseline Surface Radiation Network, which is part of a global network that provides data to scientists worldwide.
The project was supported by funding from the Swiss National Science Foundation.