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

Abstract

This paper presents the passive reflectometry and interferometry system (PARIS) concept and how it originated in the European Space Agency (ESA), Noordwijk, The Netherlands, in 1993 as a novel method to perform mesoscale ocean altimetry. The PARIS concept uses signals of opportunity such as the signals from the global navigation satellite systems (GNSS), which are reflected off the ocean surface to perform mesoscale ocean altimetry. Essentially, the relative delay between the direct and the reflected signals received from a Low Earth Orbit satellite provides information about sea surface height. The paper describes an original experiment on sea surface altimetry using GPS-reflected signals. The objective of the experiment was to demonstrate the potential of the PARIS concept. This experiment is the first one ever published on performing sea surface height estimations using reflected navigation signals in a controlled environment. The key result of the experiment is the demonstration of a root mean squared (RMS) height accuracy within 5 s of 1% of the used code chip (3 m for C/A code). Direct extrapolation of this experimental result to the 10-times higher chip rate P-code signal allows 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 systems. Index Terms-Global navigation satellite systems (GNSSs) reflected signals, mesoscale ocean, ocean altimetry.

Carrier phase wind-up in GPS reflectometry

“…In this section a signal is considered which is transmitted by a crossed dipole and coherently reflected from a plane, mirror-like surface at an incidence angle θ (e.g., Anderson, 2000;Treuhaft et al, 2001;Martín-Neira et al, 2001;Cardellach et al, 2006). In the following, incoherent signal components in the reflected signal are not taken into account.…”

Use of Satellite Radar Bistatic Measurements for Crop Monitoring: A Simulation Study on Corn Fields

“…Bistatic applications were investigated in the fields of target detection [6,7] and planetology [8]. As for Earth Observation, oceanographic studies exploiting the GPS signal were carried out, including altimetric applications (measure of the sea level and of the associated oceanographic features) and scatterometric applications (measure of the near surface wind field) [9,10], while interferometric applications were addressed in [11]. In consequence of the recent launch of the new generation of X-band radars (TerraSAR-X, COSMO-SkyMed), experiments involving X-band have been accomplished in order to evaluate the additional information contained in the bistatic reflectivity of targets (e.g., [12]).…”

Observing and understanding the Earth system variations from space geodesy

“…The first GPS signals reflected from the sea surface inside tropical cyclones were analyzed, and the wind speed results were obtained (Katzberg et al, 2001). Currently, the GPS reflected signals from the ocean surface can measure sea surface height with the achievable accuracy (Martin-Neira et al, 2001;Katzberg and Dunion, 2009). …”