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By Stephen Luntz

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GPS Signal Bending Improves Weather Forecasts
A new way of measuring atmospheric conditions is proving particularly valuable in Australia, increasing the accuracy of weather forecasts and climate modelling.

The world has become accustomed to the use of satellites for weather forecasting, but the infrared measurements used over the past few decades only provide part of the picture needed for accurate predictions.

However, NASA and NOAA scientists in the United States found that a different part of the picture could be gained by examining how GPS signals bend as satellites rise or set relative to each other. “The refractive index of air is temperature-related,” says Prof John Le Marshall of RMIT. “So when the temperature changes, the signal bends like light going into water.”

Satellite positions are known with such accuracy that the extent of this bending can be calculated when the signal appears to suggest that one of the satellites is transmitting from a slightly incorrect location.

The GPS constellation of satellites, along with a handful of others, is large enough to supply sufficient data on atmospheric temperatures in different parts of the world, although Le Marshall says the addition of several to be launched soon will be useful.

Le Marshall was Inaugural Director of the Joint Centre for Satellite Data...

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