Sea Wind Speed Estimation from Power Waveforms of GNSS-R Delay Signals of Beidou MEO Satellite

Abstract

This paper focuses the characteristics of power waveforms according to different wind speed of sea surface and then sea wind speed is estimated from the amplitude of power waveforms. The power waveforms are generated from the delay signals of Beidou MEO satellite. The remote sensing of GNSS concept is utilized to get information from sea surface. Because, this technique has been already proved as an effective tool to retrieve significant information from earth's surface since last twenty years. Still now, it has been utilizing as an advance technique for sea state monitoring, i.e. sea wind speed & direction, sea wave height, sea roughness measurement and so on. It is mainly generated the waveforms of Beidou MEO satellite for direct and reflected signals. It is obtained that the amplitude & shape of these power waveforms are varying according to wind speed. It is indicated that there is a sharp relationship between the amplitude of the waveforms and sea wind speeds. Two models are used to generate the waveforms from reflected signals. The wave spectrum model is used to find sea surface slopes i.e. up & cross variance and these up & cross variance is used as input on Z-V scattering model to generate power waveforms. The real wind speed of the experiment site of GNSS-R data collection for same time domain is also collected. The linear regression method is used to established a relationship between wind speeds and amplitudes of the waveforms. This relation is used to measure the sea wind speed. It is found that estimated wind speeds are matched closely with real wind speed and model waveforms performs good results with real data waveforms.