Sydney : The satellite-based global positioning system (GPS) technology that guides modern car navigation systems is now being used to improve weather forecasts, says a researcher at Australia s Royal Melbourne Institute of Technology (RMIT) University.

Researchers at the varsity s Satellite Positioning for Atmosphere, Climate and Environment (SPACE) Research Centre and the Bureau of Meteorology are using GPS and low earth orbit satellites to provide an additional type of temperature profile observation for use in weather forecasting computer models.

The computer models draw on about a 100,000 million current weather observations, including data from 30-40 complementary satellite instruments, to generate the information used by meteorologists to prepare weather forecasts, according to an RMIT statement.

Adjunct professor John Le Marshall, programme leader at the Bureau of Meteorology, said: "What we ve found through our work with RMIT s SPACE research team is that the GPS data improves the real-time temperature field and the cross-calibration of the data from a number of satellite instruments.

"This in turn significantly increases the usable quality of the satellite observations," Le Marshall added. "We are actually able to measure the amount of bending in the GPS beam as it passes through the atmosphere. We can then use that knowledge to more accurately measure atmospheric temperatures and use this to improve temperature fields and calibrate other satellite readings."

"This extra information, in the data-sparse southern hemisphere, is now making our forecasts more accurate," Le Marshall said. The researcher said that "since the study was completed and began being used in forecasts this year, we estimate the Bureau is now delivering forecasts of the same accuracy 10 hours earlier."

He predicts that, as techniques improve, GPS data will also play a bigger role in climate monitoring and severe weather warnings.