Evert Attema

Flexible Dynamic Block Adaptive Quantization for Sentinel-1 SAR Missions

The letter introduces a novel quantizer suited for medium to high-resolution synthetic aperture radar (SAR) systems, like the forthcoming SENTINEL-1 SAR. The Flexible Dynamic Block Adaptive Quantization (FDBAQ) extends the concept of the Block Adaptive Quantization (BAQ), used in spaceborne SAR since the Magellan mission, by adaptively tuning the quantizer rate according to the local signal-to-noise-ratio (SNR). A design is presented aiming to optimize the average bit-rate, while constraining the minimum SNR. FDBAQ optimized performance is then evaluated using backscatter maps derived from ENVIronment SATellite (ENVISAT) data.

Sentinel-1 radar mission: Status and performance

The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This describes the Sentinel-1 mission, as imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of mission requirements, its applications and the technical concepts for the system.

Sentinel-1, the GMES radar mission

The ESA Sentinels constitute the first series of operational satellites responding to the Earth Observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This paper describes the Sentinel-1 mission, an imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of the mission requirements, its applications and the preliminary technical concept for the system.

The European GMES Sentinel-1 Radar Mission

The ESA Sentinels constitute the first series of operational satellites responding to the Earth observation needs of the EU-ESA Global Monitoring for Environment and Security (GMES) programme. The GMES space component relies on existing and planned space assets as well as on new complementary developments by ESA. This paper describes the Sentinel-1 mission, an imaging synthetic aperture radar (SAR) satellite constellation at C-band. It provides an overview of the mission requirements, its applications and the preliminary technical concept for the system.

Radar Signature Measurements During The Agriscatt Campaigns

For the d etailed definition of future earth observation missions for a griculture and forestry, it is required to take into account the reflection and emission characteristics of the targets of interest. For active microwave instruments, the radar signatures of agricultural crops and forests are required. In view of the lack of sufficiently comprehensive historical data sets, ESA decided, partly in cooperation with the J oint Research Centre of the European Comnunity (JRC), to carry out a series of airborne radar campaigns to measure the radar echo from agricultural crops, bare soils and forests as a function o f radar frequency, polarisation, and incidence a ngle during the growing season on several tests sites in Europe. During radar coverage, cwprehensive ground data collection was carried o ut. In this paper, an overview will be given of the complementary deployment of airborne scattermeters and imaging radars d uring AGRISCATT, as well as the ground data collection. Samples of the first results will be shown.

A Closed-Form Expression Relating Classification Accuracy to SAR System Calibration Uncertainty

The choice of synthetic aperture radar (SAR) system design parameters such as radiometric calibration uncertainty and noise-equivalent sigma zero has a significant impact on applications exploiting SAR image data. However, methods for quantitatively translating the impact of system and mission parameter choices into the application context are lacking. This letter addresses this subject and derives a closed-form algebraic expression for translating radiometric biases due to calibration uncertainties-an important SAR engineering specification-into estimates of classification uncertainties for the restricted case of two homogeneous classes characterized by different backscatter intensity levels. The expression is exploited within this letter to estimate the potential impact of radiometric uncertainty on SAR-derived thematic maps. The results indicate that classification results based on the joint use of data from future SAR constellations in particular may be significantly degraded due to calibration uncertainties.

Surface roughness characterization for SAR applications

In this paper is proposed an alternative description of the roughness state of bare soil surfaces at the scale of the homogenous agricultural field. As a first step, the roughness power spectra of experimental profiles acquired over various test-sites in Europe are thoroughly investigated to characterize the main features of the different tillage states. Then, a novel roughness parameter is obtained by integrating the filtered power spectral density of the surface over a frequency band centered on the resonant Bragg frequency. This parameter can describe the roughness effectively seen by the SAR sensor at the scale of the field. Finally, the roughness parameter stability and its impact on the backscattered /spl sigma//spl deg/ are assessed with a view on investigating issues of parameters retrieval.