The PARIS concept: An experimental demonstration of sea surface altimetry using GPS reflected signals

This paper presents the passive reflectometry and interferometry system (PA RIS) concept and how it originated in the European Space Agency (ESA), Noor dwijk, The Netherlands, in 1993 as a novel method to perform mesoscale ocea n altimetry. The PARIS concept uses signals of opportunity such as the sign als from the global navigation satellite systems (GNSS), which are reflecte d off the ocean surface to perform mesoscale ocean altimetry Essentially, t he relative delay between the direct and the reflected signals received fro m a Low Earth Orbit satellite provides information about sea surface height . The paper describes an original experiment on sea surface altimetry using G PS-reflected signals. The objective of the experiment was to demonstrate th e potential of the PARIS concept. This experiment is the first one ever pub lished on performing sea surface height estimations using reflected navigat ion signals in a controlled environment, The key result of the experiment i s the demonstration of a root mean squared (RR;IS) height accuracy within 5 s of 1% of the used code chip (3 m for CIA code). Direct extrapolation of this experimental result to the 10-times higher chip rate P-code signal all ows us to predict a height error of 30 cm in 5 s, provided adequate models are used to take into account systematic effects. The paper ends presenting the potential of the PARIS concept for long term ocean altimetric observations in view of the current trends of the GNSS sys tems.