The ENVISAT advanced synthetic aperture radar system

Desnos, Yves-Louis; Buck, Christopher; Guijarro, J.; Levrini, G.; Suchail, J.-L.; Torres, Ramón; Laur, H.; Closa, Josep; Rosich, Betlem

doi:10.1109/igarss.2000.858057

Cited by 14 publications

(9 citation statements)

References 2 publications

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“…All these C-band SAR images are VV-polarized with a nominal spatial resolution of 30 × 30 m [23]. The ASAR system has been designed to provide continuity with ERS SAR by the European Space Agency (ESA).…”

Section: Methodsmentioning

confidence: 99%

Mechanisms of SAR Imaging of Shallow Water Topography of the Subei Bank

Zhang

Zheng

et al. 2017

Remote Sensing

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Abstract:In this study, the C-band radar backscatter features of the shallow water topography of Subei Bank in the Southern Yellow Sea are statistically investigated using 25 ENVISAT (Environmental Satellite) ASAR (advanced synthetic aperture radar) and ERS-2 (European Remote-Sensing Satellite-2) SAR images acquired between 2006 and 2010. Different bathymetric features are found on SAR imagery under different sea states. Under low to moderate wind speeds (3.1~6.3 m/s), the wide bright patterns with an average width of 6 km are shown and correspond to sea surface imprints of tidal channels formed by two adjacent sand ridges, while the sand ridges appear as narrower (only 1 km wide), fingerlike, quasi-linear features on SAR imagery in high winds (5.4~13.9 m/s). Two possible SAR imaging mechanisms of coastal bathymetry are proposed in the case where the flow is parallel to the major axes of tidal channels or sand ridges. When the surface Ekman current is opposite to the mean tidal flow, two vortexes will converge at the central line of the tidal channel in the upper layer and form a convergent zone over the sea surface. Thus, the tidal channels are shown as wide and bright stripes on SAR imagery. For the SAR imaging of sand ridges, all the SAR images were acquired at low tidal levels. In this case, the ocean surface waves are possibly broken up under strong winds when propagating from deep water to the shallower water, which leads to an increase of surface roughness over the sand ridges.

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Section: Methodsmentioning

confidence: 99%

Mechanisms of SAR Imaging of Shallow Water Topography of the Subei Bank

Zhang

Zheng

et al. 2017

Remote Sensing

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“…ESA's follow-on mission is ENVISAT, which was launched in March 2002. It carries a C-band dual-polarization system with swath widths varying between 100 and 400 km (Attema, 1991;Desnos et al, 2000). The Canadian Space Agency's RADARSAT-1, a C-band HH system available at varying incidence angles, resolutions, and swath widths (40-500 km), was launched in 1995 and continues to provide valuable images into 2004.…”

Section: Instrument Characteristics Heritage and Legacy Instrumentsmentioning

confidence: 99%

Seasat—A 25-year legacy of success

Evans

Alpers

Cazenave

et al. 2005

Remote Sensing of Environment

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“…ASAR, PALSAR, RADARSAT) (Van der Velde et al 2008). The medium resolution ASAR Wide Swath mode (Desnos et al 2000) on the other hand, has a wider swath (405 km) than higher resolution modes (e.g. Image mode) and provides shorter revisit intervals (3 -5 days compared to 35 days for Image mode).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of spaceborne radar to near-surface soil moisture in grasslands across southern Ireland

2012

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Word Count: 7241Sensitivity of spaceborne radar to near-surface soil moisture in grasslands across southern IrelandThe amount of water stored in the soil is a key parameter for the energy and mass fluxes at the land surface and is of fundamental importance to many agricultural, meteorological, biological and biogeochemical processes. This study investigates the potential of retrieving surface soil moisture in grassland areas from a time series of 68 ENVISAT Advanced Synthetic Aperture Radar (ASAR) Wide Swath Mode (WSM) scenes, acquired between 2007 and 2009, using an empirical regression approach. WSM data enables larger areas to be observed with a higher temporal sampling capability, compared to Image Mode (IM) data, and provide an appropriate spatial resolution for regional applications. As expected, the radar backscatter signal was found to increase with increasing soil moisture. Interseasonal analysis showed that the VV (Vertical transmit-Vertical receive) polarisation radar signal is more sensitive to surface soil moisture during the spring and autumn months, where average signal increases of about 4dB corresponding to relative soil moisture increases of ~40% were obtained. Results also display significant (p< 0.05) correlations between the HH (Horizontal transmit -Horizontal receive) polarisation signal and surface soil moisture, with r 2 values ranging from 0.67 -0.86 for some of the test sites. Overall, the results suggest that the use of an empirical linear relationship approach is a good approximation of the relationship between ASAR WSM backscatter coefficients and surface soil moisture over grassland areas.

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The ENVISAT advanced synthetic aperture radar system

Cited by 14 publications

References 2 publications

Mechanisms of SAR Imaging of Shallow Water Topography of the Subei Bank

Mechanisms of SAR Imaging of Shallow Water Topography of the Subei Bank

Seasat—A 25-year legacy of success

Sensitivity of spaceborne radar to near-surface soil moisture in grasslands across southern Ireland

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