Sea Altimetry and Scaterometry Using Gps Earth Reflected Signals
نویسندگان
چکیده
The Global Navigation Satellite Systems (GNSS) transmit L-band signals (see the Reference [1]). The GNSS receivers, as its main objective, measure the time elapsed from the transmission to the reception of L Band signals to infer the distance transmitter-receiver and to derive the three coordinates and time status of the receiver. The same signals could be recorded after its reflection on the Earth Surface. The shape of such reflected signals could be used to infer the rugosity of the sea surface (scatterometry) and its delay contain information on the position of the reflecting surface (altimetry). This concept, called GNSS-Reflections (GNSS-R) or PAssive Reflectometry and Interferometry System (PARIS) was proposed in 1993 [2]. The main observables produced by the present GNSS-R receivers are the waveforms: the cross-correlation of the reflected signals with its computed replicas when available. (See [3] for a description of such signals). Different research groups have carried out experiments whith the aim of exploring the capacity of the technique for the remote sensing of the different components of the Earth surface (sea, ice, soil moisture, etc). The following references are some examples: [4], [5], [6], [7], [8], [9], [10] Our goal is to provide a method to obtain, from each recorded waveform, two quantities: the specular and the scatterometic delays which contains the information needed to determine the sea surface state and the mean sea level. To verify the adequacy and the limitations of such method we acquired GNSS-R data during a flying a receiver at 3000 meters altitude. We will describe the results obtained and discuss the limitations of the proposed technique.
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