New GNSS tide gauge
A new way of measuring sea level using GNSS has been found by scientists at Chalmers University of Technology, Sweden.
The land-based GNSS tide gauge uses satellite signals that arrive both direct and reflected off the sea surface, using 2 antennas covered by small white radomes. By analyzing these signals together, the sea level and its variation can be measured at up to 20 times per second.
Hence the tide gauge can measure changes in both land and sea at the same time, in the same location - so both long- and short-term land movements, such as post-glacial rebound and earthquakes, can be monitored. Measurement of sea level can be made relative to both the coast and the centre of the Earth.
The University explains that sea level time series is rich in physical phenomena such as tides (caused mostly by the gravitational pull of the Moon and the Sun), meteorological signals (high and low pressure) and effects of climate change.
Prof Gunnar Elgered explains 'Our tide gauge station will become part of a network of stations along the coast of Sweden that will be able to monitor changes in the water level to millimetre precision well into the future'.
The developing scientists, Johan Löfgren and Rüdiger Haas, have also shown that existing coastal GNSS stations - installed primarily for the purpose of measuring land movements - can be used to make sea level measurements . . 'We’ve successfully tested a method where only one of the antennas is used to receive the radio signals. That means that existing coastal GNSS stations - there are hundreds of them all over the world - can also be used to measure the sea level.'
Details from Chalmers University below . .