Abstract
The European Space Agency Passive Reflectometry and Interferometry System In-orbit Demonstrator (IoD) aims to perform mesoscale altimetric observations by measuring the Global Navigation Satellite System (GNSS) opportunity signals reflected over the sea surface. Altimetry based on GNSS reflectometry (GNSS-R) is significantly affected by satellite motion, since it requires relatively long integration times to reduce noise. We present the impact of the satellite motion on the GNSS-R observables and the need to retrack the waveforms. By using a detailed GNSS-R space mission simulator, the change of delay difference between the direct and the reflected signals during the incoherent averaging of the waveform has been investigated. Their effects on the waveform shape and the altimetric performance are presented comparing the aligned and non-aligned waveforms. Results show that the performance of spaceborne GNSS-R altimeter is seriously degraded without a proper alignment of the waveform samples.
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References
Cardellach E, Rius A (2008) A new technique to sense non-Gaussian features of the sea surface from l-band bi-static GNSS reflections. Remote Sens Environ 112(6):2927–2937. doi:10.1016/j.rse.2008.02.003
Clarizia MP, Gommenginger CP, Gleason S, Srokosz MA, Galdi C, Bisceglie MD (2009) Analysis of GNSS-R delay-Doppler maps from the UK-DMC satellite over the ocean. Geophys Res Lett 36:L02608. doi:10.1029/2008GL036292
Ferre-Lillo P, Rodriguez-Alvarez N, Bosch-Lluis X, Valencia E, Marchan-Hernandez J, Camps A (2009) Delay-Doppler maps study over ocean, land and ice from space. In: Proceedings of IGARSS 2009, IEEE international geoscience and remote sensing symposium 2: II-722-II-725. doi:10.1109/IGARSS.2009.5418190
Garrison J, Komjathy A, Zavorotny V, Katzberg S (2002) Wind speed measurement using forward scattered GPS signals. IEEE Trans Geosci Remote Sens 40(1):50–65. doi:10.1109/36.981349
Germain O, Ruffini G (2006) A revisit to the GNSS-R code range precision, arXiv:physics/0606180v1. In: Proceedings of the GNSS-R ‘06 workshop, 14–15 June 2006, ESA/ESTEC, Noordwijk, The Netherlands
Germain O, Ruffini G, Soulat F, Caparrini M, Chapron B, Silvestrin P (2004) The Eddy experiment: GNSS‐R speculometry for directional sea‐roughness retrieval from low altitude aircraft. Geophys Res Lett 31:L21307. doi:10.1029/2004GL020991
Gleason S (2006) Remote sensing of ocean, ice and land surfaces using bistatically scattered GNSS signals from low earth orbit. Dissertation, University of Surrey
Gleason S, Hodgart S, Sun Y, Gommenginger C, Mackin S, Adjrad M, Unwin M (2005) Detection and processing of bistatically reflected GPS signals from low earth orbit for the purpose of ocean remote sensing. IEEE Trans Geosci Remote Sens 43(6):1229–1241. doi:10.1109/TGRS.2005.845643
Gleason S, Gommenginger C, Cromwell D (2010) Fading statistics and sensing accuracy of ocean scattered GNSS and altimetry signals. Adv Space Res 46(2):208–220. doi:10.1016/j.asr.2010.03.023
Komjathy A, Armatys M, Masters D, Axelrad P, Zavorotny V, Katzberg S (2004) Retrieval of ocean surface wind speed and wind direction using reflected GPS signals. J Atmos Oceanic Technol 21(3):515–526. doi: 10.1175/1520-0426(2004)021<0515:ROOSWS>2.0.CO;2
Lowe ST, LaBrecque JL, Zuffada C, Romans LJ, Young LE, Haji GA (2002) First spaceborne observation of an Earth-reflected GPS signal. Radio Sci 37(1):1007. doi:10.1029/2000RS002539
Marchan-Hernandez J, Rodriguez-Alvarez N, Camps A, Bosch-Lluis X, Ramos-Perez I, Valencia E (2008) Correction of the sea state impact in the L-Band brightness temperature by means of Delay-Doppler maps of global navigation satellite signals reflected over the sea surface. IEEE Trans Geosci Remote Sens 46(10):2914–2923. doi:10.1109/TGRS.2008.922144
Marchan-Hernandez J, Valencia E, Rodriguez-Alvarez N, Ramos-Perez I, Bosch-Lluis X, Camps A, Eugenio F, Marcello J (2010) Sea-State determination using GNSS-R data. IEEE Geosci Remote Sens Lett 7(4):621–625. doi:10.1109/LGRS.2010.2043213
Martin-Neira M (1993) A passive reflectometry and interferometry system (PARIS)—application to ocean altimetry. ESA J 17(4):331–355
Martin-Neira M, Caparrini M, Font-Rossello J, Lannelongue S, Vallmitjana C (2001) The PARIS concept: an experimental demonstration of sea surface altimetry using GPS reflected signals. IEEE Trans Geosci Remote Sens 39(1):142–150. doi:10.1109/36.898676
Martin-Neira M, D’Addio S, Buck C, Floury N, Prieto-Cerdeira R (2011) The PARIS ocean altimeter In-Orbit demonstrator. IEEE Trans Geosci Remote Sens. doi:10.1109/TGRS.2010.2092431
Park H, Marchan-Hernandez J, Rodriguez-Alvarez N, Valencia E, Ramos-Perez I, Bosch-Lluis X, Camps A (2010) End-to-end simulator for global navigation satellite system reflectometry space mission. In: Proceedings of IGARSS 2010, IEEE international geoscience and remote sensing symposium, vol 1, pp 4294–4297. doi:10.1109/IGARSS.2010.5650564
Rius A, Cardellach E, Martin-Neira M (2010) Altimetric analysis of the Sea-Surface GPS-Reflected signals. IEEE Trans Geosci Remote Sens 48(4):2119–2127. doi:10.1109/TGRS.2009.2036721
Rius A, Nogués-Correig O, Ribó S, Cardellach E, Oliveras S, Valencia E, Park H, Tarongí J, Camps A, Van der Marel H, Van Bree R, Altena B, Martín-Neira M (2011) Altimetry with GNSS-R interferometry: first proof of concept experiment, GPS Solut. doi:10.1007/s10291-011-0225-9
Ruffini G, Soulat F, Caparrini M, Germain O, Martin-Neira M (2004) The eddy experiment: accurate GNSS-R ocean altimetry from low altitude aircraft. Geophys Res Lett 31:L12306. doi:10.1029/2004GL019994
Valencia E, Camps A, Bosch-Lluis X, Rodriguez-Alvarez N, Ramos-Perez I, Marchan-Hernandez J (2010) Brightness temperature correction of the sea state effect using GNSS-R data. In: Proceedings MicroRad, 11th specialist meeting on microwave radiometry and remote sensing of the environment, vol 1, pp 129–133. doi:10.1109/MICRORAD.2010.5559574
Valencia E, Camps A, Rodriguez-Alvarez N, Ramos-Perez I, Bosch-Lluis X, Park H (2011a) Improving the accuracy of sea surface salinity retrieval using GNSS-R data to correct the sea state effect. Radio Sci (accepted)
Valencia E, Camps A, Marchan-Hernandez J, Park H, Bosch-Lluis X, Rodriguez-Alvarez N, Ramos-Perez I (2011b) Ocean surface’s scattering coefficient retrieval by delay-doppler map inversion. IEEE Geosci Remote Sens Lett. doi:10.1109/LGRS.2011.2107500
Zavorotny V, Voronovich A (2000) Scattering of GPS signals from the ocean with wind remote sensing application. IEEE Trans Geosci Remote Sens 38(2):951–964. doi:10.1109/36.841977
Acknowledgments
This work is supported by Spanish grant “GNSSR4SMOSops” from the MICCIN ref. AYA2008-05906-C02-01/ESP and by the National Research Foundation of Korea Grant funded by the Korean Government [NRF-2011-357-D00273].
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Park, H., Camps, A., Valencia, E. et al. Retracking considerations in spaceborne GNSS-R altimetry. GPS Solut 16, 507–518 (2012). https://doi.org/10.1007/s10291-011-0251-7
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DOI: https://doi.org/10.1007/s10291-011-0251-7