Projectes de transferència

 The study seeks to establish the physical relation between GNSS-R signals and ocean wind and roughness properties using state-of-the-art modelling of the ocean roughness, ocean dielectric properties and NSS-R scattering. Based on this physical understanding, the study defines the Level 2 scatterometric products that can be reliably extracted from GNSS-R signals and develops the physically based Geophysical Model Functions and error models. The physical framework also serves to characterise aspects of the TDS-1 GNSS-R signals that are specific to the TDS-1 mission and determines how these specificities impact the “ideal” GMFs derived from the simulator framework. This is subsequently used to consolidate the Level 1-to-Level 2 inversion algorithms for TDS-1, which are validated using a larger TDS-1 matchup dataset with a wider range of independent measurements. Finally, the study carries out preliminary impact analyses of the TDS-1 data and defines suitable Observation System Simulation Experiment (OSSEs) to further investigate the impact of GNSS-R wind and roughness measurements in possible future activities. The project features a logical flow starting from the physical knowledge of the sea surface drivers of GNSS-R signals acquired with the GNSS-R simulator framework. As such, the study represents an essential complement to empirical analyses of GNSS-R and TDS-1 data undertaken elsewhere, e.g. Foti et al., (2015a, 2015b), the parallel “TDS-1 Exploitation Phase” ESA study and within the CYGNSS team (e.g. Jelenak et al., 2015). The physical framework will provide the means to unravel and separate different geophysical effects, such as the relative importance of wind and ocean waves on GNSS-R signals and the nature of their response to direction. Similarly, the physical framework provides a new tool to discriminate instrument, orbit, geometrical and geophysical effects that are difficult to untangle from empirical analyses alone. Another, more implicit, objective of this study is to stimulate investigation and exploitation of the TDS-1 GNSS-R data by a wider scientific community. Although the TDS-1 data has been publicly available since arch 2015, the uptake outside NOC and SSTL has been limited. Engaging a wider scientific community in this endeavour would help to more rapidly identify issues with the data, and extend the range of solutions and approaches to understand and exploit the information content of GNSS-R signals.