Title
First Precise Spaceborne Sea Surface Altimetry With GNSS Reflected Signals
Abstract
The precision of sea surface altimetry using bistatically reflected signals of the Global Navigation Satellite System (GNSS) is typically one to two orders of magnitude worse than dedicated radar altimeters. However, when the scattering is coherent, the electromagnetic phase of the carrier signal can be tracked, providing precise ranging measurements. Under grazing angle (GA) geometries, the conditions for coherent scattering are maximized, enabling carrier phase-delay altimetric techniques over sea waters. This work presents the first implementation of GA carrier phase sea surface altimetry using data acquired from a spaceborne platform (NASA Cyclone GNSS mission) and transmitted from both GPS and Galileo constellations. The altimetric results show that the measurement system precision is 3/4.1 cm (median/mean) at 20 Hz sampling, cm level at 1 Hz, comparable to dedicated radar altimeters. The combined precision, including systematic errors, is 16/20 cm (median/mean) precision at 50 ms integration (a few cm level at 1 Hz). The wind and wave requirements to enable coherent scattering at GA geometries appear to be below 6 m/s wind and 1.5 m significant wave height, although only 33% of tracks under these conditions present sufficient coherence. Given that this technique could be implemented by firmware updates of existing GNSS radio occultation missions, and given the large number of such missions, the study indicates that the resulting precision and spatio–temporal resolution would contribute to resolving some submesoscale ocean signals.
Year
DOI
Venue
2020
10.1109/JSTARS.2019.2952694
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Keywords
DocType
Volume
Carrier phase-delay altimetry,Global Navigation Satellite System (GNSS) reflectometry,grazing angle (GA) reflectometry,sea surface altimetry,submesocale ocean altimetry
Journal
13
ISSN
Citations 
PageRank 
1939-1404
0
0.34
References 
Authors
0
8
Name
Order
Citations
PageRank
Estel Cardellach15314.11
Weiqiang Li2238.00
Antonio Rius313222.33
Maximilian Semmling4244.83
Jens Wickert54427.67
Florian Zus632.17
Christopher S. Ruf741663.82
Carlo Buontempo831.21