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A Measurement Quality Factor for Swath Bathymetry Sounders ArchiMer
Lurton, Xavier; Augustin, Jean-marie.
The quality estimation associated with individual soundings measured and computed by swath bathymetry sonars is a paramount issue which is most often imperfectly addressed today by sonar manufacturers. In this paper, a unified definition is proposed for a quality factor usable for all swath bathymetry sonars; the depth-relative error is directly estimated from the signal characteristics used in the sounding computation. The basic algorithms are presented for both phase-difference (oblique incidence) and amplitude (normal incidence) detection, and can be readily implemented in any swath bathymetry system using these detection principles. This approach gives a direct access to the objective bathymetric performance of individual soundings, and hence avoids...
Tipo: Text Palavras-chave: Bathymetry; Interferometry; Multibeam echosounder (MBES); Sonar.
Ano: 2010
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Mapping forest successional stages in the Brazilian Amazon using forest heights derived from TanDEM-X SAR interferometry. Repositório Alice
BISPO, P. da C.; PARDINI, M.; PAPATHANASSIOU, K. P.; KUGLER, F.; BALZTER, H.; RAINS, D.; SANTOS, J. R. dos; RIZAEV, I. G.; TANSEY, K.; SILVA, M. F. da; ARAUJO, L. S. de.
Abstract: Knowledge of the spatial patterns of successional stages (i.e., primary and secondary forest) in tropical forests allows to monitor forest preservation, mortality and regeneration in relation to natural and anthropogenic disturbances. Different successional stages have also different capabilities of re-establishing carbon stocks. Therefore, a successful discrimination of successional stages over wide areas can lead to an improved quantification of above ground biomass and carbon stocks. The reduction of the mapping uncertainties is especially a challenge due to high heterogeneity of the tropical vegetation. In this framework, the development of innovative remote sensing approaches is required. Forests (top) height (and its spatial distribution)...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Forest height; Synthetic aperture radar; TanDEM-X; Floresta Tropical; Mapa; Sensoriamento Remoto; Tropical forests; Forest succession; Height; Interferometry.
Ano: 2019 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1115303
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Performances study of interferometric radar altimeters: from the instrument to the global mission definition ArchiMer
Enjolras, Vivien; Vincent, Patrick; Souyris, Jean-claude; Rodriguez, Ernesto; Phalippou, Laurent; Cazenave, Anny.
The main limitations of standard nadir-looking radar altimeters have been known for long. They include the lack of coverage (intertrack distance of typically 150 km for the T/P / Jason tandem), and the spatial resolution ( typically 2 km for T/P and Jason), expected to be a limiting factor for the determination of mesoscale phenomena in deep ocean. In this context, various solutions using off-nadir radar interferometry have been proposed by Rodriguez and al to give an answer to oceanographic mission objectives. This paper addresses the performances study of this new generation of instruments, and dedicated mission. A first approach is based on the Wide-Swath Ocean Altimeter (WSOA) intended to be implemented onboard Jason-2 in 2004 but now abandoned. Every...
Tipo: Text Palavras-chave: Altimetry; Interferometry; Error budget; System analysis; Ocean; Mesoscale.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/00284/39507/38002.pdf
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Simple method for multiple soundings extraction for wide beamwidth echosounders ArchiMer
Le Bouffant, Naig; Berger, Laurent; Lurton, Xavier.
Bathymetric multibeam echosounders (MBES) classically improve their bottom detection resolution by increasing the number of beams with narrower beamwidths. Many independent detections are thus obtained when extracting one sounding in each beam. However when the pulse footprint on the bottom gets narrower than the beamwidth, which often happens at high incidence angles, it is possible to extract several independent bottom detections within the same beam. These high-density soundings extraction methods present a still higher interest for MBES designed with rather “wide” beams (say 3° or more), so as to offer other benefits, such as compacity, low-cost, or low sidelobe levels as for fishery applications. This paper presents a simple way to derive multiple...
Tipo: Text Palavras-chave: Multibeam; Bathymetry; Interferometry; Beamwidth.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00146/25719/23801.pdf
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Swath bathymetry using phase difference: Theoretical analysis of acoustical measurement precision ArchiMer
Lurton, Xavier.
The phase difference principle is widely applied nowadays to sonar systems used for sea floor bathymetry, The apparent angle of a target point is obtained from the phase difference measured between two close receiving arrays. Here we study the influence of the phase difference estimation errors caused by the physical structure of the backscattered signals. It is shown that, under certain current conditions, beyond the commonly considered effects of additive external noise and baseline decorrelation, the processing may be affected by the shifting footprint effect: this is due to the fact that the two interferometer receivers get simultaneous echo contributions coming from slightly shifted seabed parts, which results in a degradation of the signal coherence...
Tipo: Text Palavras-chave: Sonar signal processing; Sidescan sonar; Sea floor bathymetry; Multibeam echosounder; Interferometry; Bathymetry precision; Acoustic scattering.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/2000/publication-710.pdf
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The SMOS Mission: New Tool for Monitoring Key Elements of the Global Water Cycle ArchiMer
Kerr, Yann H.; Waldteufel, Philippe; Wigneron, Jean-pierre; Delwart, Steven; Cabot, Francois; Boutin, Jacqueline; Escorihuela, Maria-jose; Font, Jordi; Reul, Nicolas; Gruhier, Claire; Juglea, Silvia Enache; Drinkwater, Mark R.; Hahne, Achim; Martin-neira, Manuel; Mecklenburg, Susanne.
It is now well understood that data on soil moisture and sea surface salinity (SSS) are required to improve meteorological and climate predictions. These two quantities are not yet available globally or with adequate temporal or spatial sampling. It is recognized that a spaceborne L-band radiometer with a suitable antenna is the most promising way of fulfilling this gap. With these scientific objectives and technical solution at the heart of a proposed mission concept the European Space Agency (ESA) selected the Soil Moisture and Ocean Salinity (SMOS) mission as its second Earth Explorer Opportunity Mission. The development of the SMOS mission was led by ESA in collaboration with the Centre National d'Etudes Spatiales (CNES) in France and the Centro para...
Tipo: Text Palavras-chave: Interferometry; L-band; Sea surface salinity (SSS); Soil moisture; Soil Moisture and Ocean Salinity (SMOS); Vegetation water content.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00004/11483/8065.pdf
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