THE ENVISAT ASAR MISSION: A LOOK BACK AT 10 YEARS OF OPERATION

The Advanced Synthetic Aperture Radar (ASAR) on- board Envisat operated successfully for just over 10 years until the failure of Envisat in April 2012. ASAR was ESA's very first deployment of a C-band phased- array antenna, allowing extended imaging capacity in comparison to its ERS SAR predecessors. As such it operated in various acquisition modes - Image (IM), Alternating Polarisation (AP), Wide Swath (WS), Global Monitoring (GM), and Wave (WV). For IM and AP modes there was a selection of 7 swaths with swath width from 100 km to 56 km: IM was single- polarisation, while AP was dual-pol, offering a choice from HH&VV, HH&HV, or VV&VH. WS and GM modes had a total swath width of 405 km based on the combination of 5 sub-swaths. WV acquired imagettes of 10 km by 10 km every 100 km along the satellite track. This paper is a look back to the 10 years of ASAR operations, covering topics such as the ASAR Instrument (characteristics, acquisition modes, product tree and observation scenario), Instrument Calibration and Performance Verification (including instrument stability, internal calibration, external calibration, absolute radiometric calibration, localisation accuracy, absolute geolocation accuracy, performance verification and product calibration), ASAR specific missions (wave and polarimetric), particular ASAR events such as

[1]  B. Chapron,et al.  Monitoring and analysis of ocean swell fields from space: New methods for routine observations , 2009 .

[2]  E. Meier,et al.  ASAR product consistency and geolocation accuracy , 2008 .

[3]  Harald Johnsen,et al.  Sea-Surface Polarization Ratio From Envisat ASAR AP Data , 2008, IEEE Transactions on Geoscience and Remote Sensing.

[4]  Betlem Rosich,et al.  Geometric and radiometric correction of ESA SAR products , 2007 .

[5]  Davide D'Aria,et al.  ASAR wide swath mode interferometry: optimization of the scan pattern synchronization , 2007 .

[6]  Davide D'Aria,et al.  REVIEW OF ASAR PERFORMANCE AND PRODUCT QUALITY EVOLUTION AFTER 5 YEARS OF OPERATIONS , 2007 .

[7]  Betlem Rosich,et al.  GLOBAL REDEPLOYMENT OF THE ENVISAT ASAR TRANSPONDERS FOR AROUND ORBIT CALIBRATION , 2007 .

[8]  Jean-Claude Souyris,et al.  Incoherent SAR polarimetric analysis over point targets , 2006, IEEE Geoscience and Remote Sensing Letters.

[9]  B. Chapron,et al.  THE IMPACT OF USING THE UPGRADE PROCESSING OF ASAR LEVEL 2 WAVE PRODUCTS IN THE ASSIMILATION SYSTEM , 2006 .

[10]  Betlem Rosich,et al.  ENVISAT ASAR Product Calibration and Product Quality Status , 2004 .

[11]  Ramon Torres,et al.  ASAR INSTRUMENT STABILITY , 2002 .

[12]  J. Closa.  INTERNAL CALIBRATION PROCESSING AND PROCESSOR NORMALIZATION , 2002 .

[13]  S. W. Tam,et al.  Envisat/ASAR Precision Transponders , 2000 .

[14]  R. Bamler,et al.  A plea for radar brightness , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[15]  Betlem Rosich,et al.  GEOMETRIC VALIDATION OF LOW AND HIGH-RESOLUTION ASAR IMAGERY , 1993 .

[16]  Betlem Rosich,et al.  Geometric Calibration and Validation of ASAR Imagery , 1993 .

[17]  F. Collard,et al.  Comparison of Reprocessed Asar Wm Ocean Wave Spectra with Wam and Buoy Spectra , 2022 .