GPS Tide Gauge Measures Sea Level Change
- Created on Wednesday, 21 May 2014
Using radio signals from satellite navigation systems, Scientists at Chalmers Department of Earth and Space Sciences have developed and tested a Global Navigation Satellite System (GNSS) tide gauge, an instrument that measures the sea level.
The GNSS tide gauge uses radio signals from satellites in orbit around the Earth that are part of satellite navigation systems like GPS and Glonass (Russia’s equivalent of GPS).
Two antennas, covered by small white radomes, measure signals both directly from the satellites and signals reflected off the sea surface. By analyzing these signals together, the sea level and its variation can be measured, up to 20 times per second.
”We measure the sea level using the same radio signals that mobile phones and cars use in their satellite navigation systems,” says researcher Johan Löfgren. “As the satellites pass over the sky, the instrument ‘sees’ their signals – both those that come direct and those that are reflected off the sea surface.”