CEOS Working Group on Calibration/Validation
SAR WORKSHOP
24 – 26 September 2002 London, United Kingdom

Foreword
G.Keyte
Over the past decade, spaceborne synthetic aperture radar (SAR) missions have consistently shown that they are capable of producing high quality radar imagery and as a consequence a large number of applications have been investigated and developed. Of particular importance have been the demonstration of SAR interferometry (InSAR) for both topography and change monitoring and the development (using both aircraft and space shuttle missions) of SAR polarimetry. Increasingly, techniques such as these are becoming important tools in the study of the Earth’s environment – and in particular, the study of the changes in the environment. One example is the potential of SAR, using both interferometric and polarimetric techniques, to determine woody biomass and hence contribute to the estimation of carbon sinks in the study of global carbon dynamics... »

Abstracts

CEOS Working Group on Calibration and Validation
CEOS WGCV document by Marie-Claire Robinson
The Working Group on Calibration and Validation (WGCV) was established in 1984. This resulted from the recognition that calibration and validation activities should play a key role in all satellite Earth Observation missions to ensure the clear and quantitative understanding of the data they generate... »

Session 1

Working Group on Calibration/Validation
Y.-L. Desons
The Working Group on Calibration and Validation (WGCV), and its six technical subgroups, continue to provide a forum for sustained debate, international co-operation and common actions. The addition of a further subgroup concerned with atmospheric chemistry has provided an important additional input to the WGCV’s work, and filled a recognised gap within the atmospheric chemistry community... »

Session 2

The ERS-2 SAR performance: another further update
P.J. Meadows & B. Rosich
The performance of the ERS-2 Synthetic Aperture Radar (SAR) is routinely assessed at the ESA Product and Archiving Facilities (PAFs) via a variety of quality assessment and calibration measures. This paper gives the latest ERS-2 SAR quality assessment and calibration results including updates to ERS-2 SAR internal calibration and stability, updates to the ERS-2 nominal replica pulse correction table, noise equivalent radar cross-section measurements and image localisation results... »

Modelling SAR Scalloping in Burst Mode Products from RADARSAT-1 and Envisat
RK Hawkins & PW Vachon
A model is developed for the quantitative prediction of the azimuth radiometric modulation, commonly known as scalloping, that is occasionally present in burst mode SAR products from RADARSAT-1 and ENVISAT... »

SAR Product Control Software
P.J. Meadows, D. Hounam, A.J. Rye, B. Rosich, T. Börner, J. Closa, B. Schättler, P.J. Smith & M. Zink
As SAR instruments and their operating modes become more complex, as new applications place more and more demands on image quality and as our understanding of their imperfections becomes more sophisticated, there is increasing recognition that SAR data quality has to be controlled more completely to keep pace... »

RADARSAT-1 Image Quality – Continuing Success in Extended Mission
S. K. Srivastava, P. Le Dantec, B. T. Banik, G. Guertin, R. Gray, R. K. Hawkins & K. Murnaghan
RADARSAT-1, the first Canadian SAR remote sensing satellite, was launched on November 4, 1995. After commissioning, it was put in to routine operations on April 1, 1996. Since then, it has been operating successfully, even after completing its five and a quarter years of design lifetime, and providing data to users for their intended applications... »

The Global SRTM X-SAR DEM – Calibration, Validation, Production Status and Results
N. Adam, H. Breit, W. Knöpfle, M. Eineder & S. Suchandt
In February 2000, the Shuttle Radar Topography Mission (SRTM) acquired a global digital elevation model (DEM) within only 11 days. Extensive testing and calibration activities primarily based on ocean surface data took place at DLR during the years 2000 and 2001... »

Session 3

ASAR Instrument Stability
R. Torres
The verification of the RF stability of the instrument in flight is of major importance. Immediately after first switch-on and before starting with the calibration activities, ASAR stability has been proven against the requirements and the expected behaviour from on-ground tests. This paper presents the techniques used and the results obtained during this exercise in order to check instrument stability at short, medium and long term... »

ASAR Instrument Gain Setting
M. Zink
Verification of the dynamic range of the ASAR raw data is necessary to ensure optimal use of the instrument capabilities... »

ASAR External Characterisation
M. Zink & H. Jackson
External characterisation is required to quantify the properties of the passive part of the antenna and the calibration network. The EC factor is derived from the difference of transmit cw pulses recorded simultaneously on-board and on the ground by a coherent receiver... »

Antenna Elevation Pattern Estimation from Rain Forest Acquisitions
M. Zink & B. Rosich
Antenna elevation pattern estimation is based on acquisitions over a large homogeneous rain forest area in the Amazon basin. The estimation procedure accepts IMP and WSM products as input and generates a combined estimate from as many input products as are available for a certain beam... »

Pattern Synthesis From Calibration Mode Measurements
R. Torres
During the first phase of the Calibration/Validation activities different methods have been used to estimate the ASAR antenna radiation patterns. Initially the pre-flight patterns from the ASAR characterisation were used. Rainforest acquisitions and the use of calibration data confirmed and improved the estimations following the in-flight tuning of the T/R modules... »

Preliminary Doppler Analysis On ASAR Products
B. Rosich
The Doppler Centroid frequency is an important instrument characterisation and key processing parameter. High Doppler estimation accuracy is needed to meet the radiometric requirements of ASAR products, and particularly for burst-mode data (ScanSAR and AP modes). On these modes, an error in the fine Doppler Centroid frequency introduces a radiometric banding error due to miss-application of descalloping functions... »

ASAR IMS & WVI Products Quality (VV Polarisation)
B. Rosich
Considering the number of modes of operation, beams and polarisations available on the ASAR instrument on board of ENVISAT, the ASAR product validation and calibration effort has been spitted in two phases. The first phase covers the first 6 months after the ENVISAT launch, i.e. the Commissioning Phase period. During this period, the effort is concentrated on Image Mode, Wave and Wide Swath VV polarisation (all beams)... »

ASAR Calibration in the Ground Processing Facility*
J. Closa & B. Rosich
*slide presentation

A First Assessment of the ASAR Wave Mode Properties and its Complex Imagette Product Characteristics
B. Schättler, B. Rosich, Josep Closa, et al.
With its ASAR wave mode, the ENVISAT mission provides a continuity of the ERS-1/2 wave mode, but with more flexible measurement capabilities and an enhanced product variety offered to the user community... »

Calibration of Interferometric Envisat/ASAR Image Mode Products
J. Holzner, M. Eineder & B. Schättler
Interferometric data processing requires careful calibration and validation of the complex input products. Interferometric calibration comprises geometric and phase accuracy aspects. With respect to geometry, orbit and timing parameter have to be calibrated in order to allow accurate geo-coding and optimal processing of the interferometric products. Phase accuracy of the input complex products is an important prerequisite for the interfe rometric measurement technique... »

Session 4

Calibration of PI-SAR (L-Band)
M. Shimada, T. Tadono & T. Umehara
We introduce a calibration result of the airborne L-band Polarimetric Interferometric SAR (shortly Pi-SAR) in this paper. Calibration consists of characterization of the SAR using the raw data (natural target data and calibration data) and the pre-launch on-ground measurement, in-flight raw data, calibration of the processed SAR data, and image quality... »

Calibration Requirements for Forest Parameter Estimation Using POLinSAR
S.R. Cloude
In this paper we consider the effects of polarimetric calibration errors on the performance of model based parameter estimation algorithms in forestry applications. In particular we concentrate on the use of Polarimetric Interferometric SAR (POLInSAR) for forest height and ground topography estimation... »

The SSCM: an Adaptation of Cameron’s Target Decomposition to Actual Calibration SAR Requirements
R. Touzi & F. Charbonneau
Cameron’s coherent target decomposition (CTD) and classification are discussed in the context of SAR, and the limitations of Cameron’s classification are ex-amined... »

Workshop Summary
G. Keyte
The workshop was held at the DTI Conference Centre, London, under the sponsorship of the British National Space Centre (BNSC). The 3-day meeting, 24 – 26 September 2002, involved about 40 participants from Europe, Japan and Canada. There were three technical sessions and an invited paper (session 1) from Yves-Louis Desnos on the objectives and programme of the CEOS Working Group on Calibration and Validation (WGCV) and the activities of the different WGCV subgroups... »

List of Participants

WGCV Workshop Presentation Panels

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry