GEO Geohazards Supersite

The ASAR Image Mode source packets Level 0 data product offers Level 0 data for possible images processing on an other processing site. It includes some mandatory information for SAR processing. The Image Mode Level 0 product consists of time-ordered Annotated Instrument Source Packets (AISPs) collected while the instrument is in Image Mode. The echo samples contained in the AISPs are compressed to 4 bits/sample using Flexible Block Adaptive Quantisation (FBAQ). This is a high-rate, narrow swath mode so data is only acquired for partial orbit segments and may be from one of seven possible image swaths. The Level 0 product is produced systematically for all data acquired within this mode. This product provides a continuation of the ERS-SAR_RAW product.

The SAR Annotated Raw Data product consists of the SAR telemetry data corresponding to 16 seconds of data collection; it also contains all required auxiliary data necessary for data processing. It is primarily used for testing the ERS-1 SAR processors independently from the HDDR system and for users interested in full SAR data processing.

The SAR Image Mode source packets Level 0 data product offers Level 0 data for possible images processing on an other processing site. It includes some mandatory information for SAR processing. The Image Mode Level 0 product consists of time-ordered Annotated Instrument Source Packets (AISPs) collected while the instrument is in Image Mode. The echo samples contained in the AISPs are compressed to 4 bits/sample using Flexible Block Adaptive Quantisation (FBAQ). This is a high-rate, narrow swath mode so data is only acquired for partial orbit segments. The Level 0 product is produced systematically for all data acquired within this mode.

The SAR Image Mode source packets Level 0 data product offers Level 0 data for possible images processing on an other processing site. It includes some mandatory information for SAR processing. The Image Mode Level 0 product consists of time-ordered Annotated Instrument Source Packets (AISPs) collected while the instrument is in Image Mode. The echo samples contained in the AISPs are compressed to 4 bits/sample using Flexible Block Adaptive Quantisation (FBAQ). This is a high-rate, narrow swath mode so data is only acquired for partial orbit segments. The Level 0 product is produced systematically for all data acquired within this mode.

The SAR Annotated Raw Data product consists of the SAR telemetry data corresponding to 16 seconds of data collection; it also contains all required auxiliary data necessary for data processing. It is primarily used for testing the ERS-1 SAR processors independently from the HDDR system and for users interested in full SAR data processing.

The ASAR Image Mode Single Look Complex Image represents a single-look, complex, slant-range, digital image generated from Level 0 ASAR data collected when the instrument is in image mode. Seven possible swaths in HH or VV polarisation are available. The product is primarily intended for use in SAR quality assessment and calibration, and can be used to derive higher level products. The spatial coverage is about 100 km along track and 100 km across track, and the radiometric resolution is 1 look in azimuth, 1 look in range. The file size is 741 Mbytes. It is worth highlighting that Azimuth pixel spacing depends on Earth-Satellite relative velocity and actual PRF and slant range pixel spacing is given by ASAR sampling frequency (19.208 Mhz).

The WS Mode Level 0 product consists of time-ordered AISPs collected while the instrument is in WS Mode. The echo samples in the AISPs have been compressed to 4 bits/sample using FBAQ. This is a high-rate, wide swath (ScanSAR) mode so data is only acquired for partial orbit segments and is composed of data from five image swaths (SS1 to SS5). The Level 0 product is produced systematically for all data acquired within this mode.

This product presents SAR data following preprocessing, but retains every sample as complex data. The product is single-look (i.e. no speckle reduction by multi-look processing) and in slant range. Phase continuity is preserved within the image. Three areas of application are testing of SAR processing algorithms, development of techniques using phase preservation, e.g. SAR interferometry, and application of SAR post-processing algorithms, e.g. geocoding from complex, slant-range data.

This is a multi-look, ground range, digital image generated from Level 0 data collected when the instrument is in Image Mode (7 possible swaths HH or VV polarisation). The product includes slant range to ground range correction. It is for users wishing to perform applications-oriented analysis and applies to multi-temporal imaging and to derive backscattering coefficients. The stand-alone image is generated using the Range/Doppler algorithm. The processing uses up to date (at time of processing) auxiliary parameters corrected for antenna elevation gain, and range spreading loss. Engineering corrections and relative calibration are applied to compensate for well-understood sources of system variability. Absolute calibration parameters, when available (depending on external calibration activities) are provided in the product annotations. This product provides a continuation of the ERS-SAR_PRI product.

This product presents SAR data following preprocessing, but retains every sample as complex data. The product is single-look (i.e. no speckle reduction by multi-look processing) and in slant range. Phase continuity is preserved within the image. Three areas of application are testing of SAR processing algorithms, development of techniques using phase preservation, e.g. SAR interferometry, and application of SAR post-processing algorithms, e.g. geocoding from complex, slant-range data.

The Precision Image is a multi-look (speckle-reduced), ground range image. The product is calibrated and corrected for the SAR antenna pattern and range-spreading loss: radar backscatter can be derived from the product for geophysical modelling, but no correction is applied for terrain-induced radiometric effects. The image is not geocoded, and terrain distortion (foreshortening and layover) has not been removed. Numbering sequence is relative to the satellite position, and so a different position for the Ascending and Descending scenes. These are 3-looks Precision Images, suitable for calibration purposes.

To date, the only operational Level-1B data product offered by ESA from the ASAR Wide-Swath Mode (WSM) has been the multi-look detected product (ASA_WSM_1P), intended to support applications that exploit intensity data. In order to support the development of new applications with the ASAR ScanSAR data, a new WSM product providing phase information has been developed and implemented in the ESA ASAR processor, the Wide-Swath Single-Look complex product (ASA_WSS_1P). It is expected that this new product will be mainly used for INSAR applications based either on wide-swath/wide-swath pairs or wide-swath/image mode pairs, applications of ocean current mapping, large-area ocean wave retrievals, and atmospheric water vapour characterisation. It shall be mentioned that the standard ESA WSS product is based on the prototype WSS processor developed by Polimi/Poliba, which has also been used to generate prototype products for testing the potential and preparing the exploitation of the new WSS product (see the first ASAR WSM-WSM interferogram). The new ESA ASA_WSS_1P product is now available as standard ENVISAT ASAR product and it can be ordered using EOLI-SA. Please contact the Earth Observation Help Desk Team for further details. The ASA_WSS_1P product format is slightly different from other ASAR products since: there are 5 different MDSs, one per sub-swath a "Doppler Grid" ADS has been included to support ocean current mapping applications there are 5 records in the MPP ADS, one per sub-swath there are 5 records in the SQ ADS, one per sub-swath Other key characteristics of the ASA_WSS_1P product are summarised below: processing is fully phase preserving data in the MDSs is sampled in a common grid both in range and in azimuth standard product is 60 sec long with 80 m az. pixel spacing auxiliary timeline information has been added in the Main Processing Parameters ADS elevation antenna pattern correction is applied by default (although the product is a single-look complex)

The Precision Image is a multi-look (speckle-reduced), ground range image. The product is calibrated and corrected for the SAR antenna pattern and range-spreading loss: radar backscatter can be derived from the product for geophysical modelling, but no correction is applied for terrain-induced radiometric effects. The image is not geocoded, and terrain distortion (foreshortening and layover) has not been removed. Numbering sequence is relative to the satellite position, and so a different position for the Ascending and Descending scenes. These are 3-looks Precision Images, suitable for calibration purposes.