GPS technology improves weather forecasting

The satellite-based Global Positioning System (GPS) technology that guides modern in-car navigation systems is now being used to improve weather forecasts.

Researchers at RMIT University’s SPACE Research Centre in Melbourne and the Australian Bureau of Meteorology are using GPS and low Earth-orbiting satellites to provide an additional type of temperature profile observation for use in weather forecasting computer models.

The computer models draw on 100 billion current weather observations, including data from 30 to 40 complementary satellite instruments, to generate the information used by meteorologists to prepare weather forecasts.

RMIT Adjunct Professor John Le Marshall said: “What we’ve found 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 said the researchers were able to measure the amount of bending in the GPS beam as it passed through the atmosphere. They could then use that knowledge to more accurately measure atmospheric temperatures and use this to improve temperature fields and calibrate other satellite readings. The extra information, in the data-sparse southern hemisphere, was making forecasts more accurate.

“Since the research 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 said. “As techniques improve, GPS data will also play a bigger role in climate monitoring and severe weather warnings.”

Centre Director Professor Kefei Zhang said GPS was a revolutionary technology and provided a low-cost, powerful means of precise measurement of the Earth environment. Weather forecasting was dependent on accurate observations of the atmosphere surrounding the whole planet, but there was a significant lack of ground-based meteorological observation stations.

That and the shortage of accurate surface-level data from over the world’s oceans and polar regions limited the reliability of climate and weather predictions.

“This is particularly true for Australia, where people live along long coastlines but forecasters can only draw on very limited measurements from the middle of the continent and surrounding oceans,” Zhang said.

“GPS can fill that gap. It’s revolutionary technology. It’s the missing link.”