Impact of the elevation angle on CYGNSS GNSS-R bistatic reflectivity as a function of effective surface roughness over land surfaces
The Earth's surface bistatic reflectivity GLHCP,CyGNSS is experimentally characterized using the novel Global Navigation Satellite Systems Reflectometry (GNSS-R) L-band passive multistatic radar technique from the Cyclone Global Navigation Satellite Systems (CyGNSS) eight-microsatellite constel...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2018 |
| País: | España |
| Institución: | Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) |
| Repositorio: | r-CTTC. Repositorio Institucional Producción Científica del Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) |
| OAI Identifier: | oai:cttc.fundanetsuite.com:p1241 |
| Acceso en línea: | https://cttc.fundanetsuite.com/Publicaciones/ProdCientif/PublicacionFrw.aspx?id=1241 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057122740&doi=10.3390%2frs10111749&partnerID=40&md5=45c96f23a0e6ce8761f3878426be8d72 |
| Access Level: | acceso abierto |
| Palabra clave: | Coherent scattering Communication satellites Correlation methods Global positioning system Incoherent scattering Moisture determination Multistatic radars Reflection Salinity measurement Satellites Soil moisture Storms Surface scattering Bistatic CyGNSS Elevation angle Global Navigation Satellite Systems GNSS-R Maximum correlation coefficient Pearson correlation coefficients Surface roughness parameters Surface roughness |
| Sumario: | The Earth's surface bistatic reflectivity GLHCP,CyGNSS is experimentally characterized using the novel Global Navigation Satellite Systems Reflectometry (GNSS-R) L-band passive multistatic radar technique from the Cyclone Global Navigation Satellite Systems (CyGNSS) eight-microsatellite constellation. The focus of this study is to evaluate the influence of the GNSS satellites' elevation angle ?e on GLHCP,CyGNSS, as a function of soil moisture content (SMC) and effective surface roughness parameter h. As the average response, the change of the scattering regime at a global scale and considering also vegetated surfaces appears at ?e ˜ 55°. This empirical observation is understood as a change on the dominant scattering term, from incoherent to coherent. Then, the correlation of GLHCP,CyGNSS and SMC is evaluated as a function of ?e over specific sparsely vegetated target areas. The smoother the surface, the higher the angular variability of the Pearson correlation coefficients. Over croplands (e.g., Argentinian Pampas), an improved correlation coefficient is achieved over angular ranges where the coherent scattering regime becomes the dominant one. As such, this function depends on the surface roughness. The maximum correlation coefficients are found at different ?e for increasing mean roughness levels: rPampas ˜ 0.78 at ?e ˜ [60,70]°, rIndia ˜ 0.72 at ?e ˜ [50,60]°, and rSudan ˜ 0.74 at ?e ˜ [30,40]°. SMC retrieval algorithms based on GNSS-R multi-angular information could benefit from these findings, so as to improve the accuracy using single-polarized signals. © 2018 by the authors. |
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