UNB RESEARCHERS STUDY THE WEATHER USING GPS

November 21, 2006

Source: University of New Brunswick - Fredericton
http://www.unb.ca/news/view.cgi?id=1165

Predicting the weather is not an exact science, but new instruments and techniques are helping meteorologists improve their forecast accuracies.

This is where Richard Langley at the University of New Brunswick in Fredericton comes in. He is helping meteorologists better their weather forecasts by analyzing the measurements made by global positioning system (GPS) receivers.

GPS receivers pick up radio signals from satellites in space. As the signals pass through the atmosphere, variations in temperature, pressure and humidity change their speed, resulting in erroneous GPS measurements.

Dr. Langley says that while radio signals are contaminated by the atmosphere, the data obtained by GPS receivers can be manipulated to reveal what the atmosphere has done to the signals.

"In particular, we can figure out how much water vapor was in the atmosphere when the GPS signals passed through it," he said. "Meteorologists can extract this information and input it into weather forecast models."

To adjust for the discrepancies in GPS measurements, Dr. Langley and his colleagues in the department of geodesy and geomatics engineering at UNBF, have developed mathematical models that correct the errors caused by atmospheric conditions. This results in more accurate readings.

"Our models improve the analysis of measurements made by a GPS receiver, resulting in more accurate positioning and navigation reporting," said Dr. Langley. "The atmosphere is a nuisance for positioning and navigation applications of GPS and our models help to make GPS better for those users."

Researchers at UNB have long been involved in developing correction models and implementing them in the software used to process GPS measurements.

"One of these models is used in virtually every GPS receiver sold today, helping the receiver to achieve the remarkable positioning and navigation accuracy that GPS affords," said Dr. Langley.

In addition to developing correction models for better GPS analysis, UNB also operates runs a number of continuously operating GPS receivers. One is solely primarily dedicated to providing data to the U.S. National Weather Service to improve its weather forecasts.

The data is also shared with the Canadian Meteorological Service, which has recently begun testing the use of GPS-derived data in its weather forecasts.

"GPS is an amazing tool for which new applications are being invented all the time," said Dr. Langley. "We can now add weather forecasting to the growing list."

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Natalie Montgomery, Public Relations Officer (506) 451-6842