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ASAR Data Formats Products
Geolocation Grid ADSRs
Doppler Centroid parameters
Chirp parameters
Antenna Elevation pattern
ASAR external characterization data
ASAR external calibration data
Level 0 SPH
Level 0 MDSR
SPH for auxiliary data with N=1 DSDs
Wave Mode Geolocation ADS
ASAR Wave Mode Products Base SPH
Slant Range to Ground Range conversion parameters
Measurement Data Set containing spectra. 1 MDSR per spectra.
Ocean Wave Spectra
Map Projection parameters
ASAR Image Products SPH
Measurement Data Set 1
Auxilliary Products
ASA_XCH_AX: ASAR External characterization data
ASA_XCA_AX: ASAR External calibration data
ASA_INS_AX: ASAR Instrument characterization
ASA_CON_AX: ASAR Processor Configuration
Browse Products
ASA_WS__BP: ASAR Wide Swath Browse Image
ASA_IM__BP: ASAR Image Mode Browse Image
ASA_GM__BP: ASAR Global Monitoring Mode Browse Image
ASA_AP__BP: ASAR Alternating Polarization Browse Image
Level 0 Products
ASA_WV__0P: ASAR Wave Mode Level 0
ASA_WS__0P: ASAR Wide Swath Mode Level 0
ASA_MS__0P: ASAR Level 0 Module Stepping Mode
ASA_IM__0P: ASAR Image Mode Level 0
ASA_GM__0P: ASAR Global Monitoring Mode Level 0
ASA_EC__0P: ASAR Level 0 External Characterization
ASA_APV_0P: ASAR Alternating Polarization Level 0 (Cross polar V)
ASA_APH_0P: ASAR Alternating Polarization Level 0 (Cross polar H)
ASA_APC_0P: ASAR Alternating Polarization Level 0 (Copolar)
Level 1 Products
ASA_IMS_1P: ASAR Image Mode Single Look Complex
ASA_IMP_1P: ASAR Image Mode Precision Image
ASA_IMM_1P: ASAR Image Mode Medium Resolution Image
ASA_IMG_1P: ASAR Image Mode Ellipsoid Geocoded Image
ASA_GM1_1P: ASAR Global Monitoring Mode Image
ASA_APS_1P: ASAR Alternating Polarization Mode Single Look Complex
ASA_APP_1P: ASAR Alternating Polarization Mode Precision Image
ASA_APM_1P: ASAR Alternating Polarization Medium Resolution Image product
ASA_WSS_1P: Wide Swath Mode SLC Image
ASA_WVS_1P: ASAR Wave Mode Imagette Cross Spectra
ASA_WSM_1P: ASAR Wide Swath Medium Resolution Image
ASA_APG_1P: ASAR Alternating Polarization Ellipsoid Geocoded Image
Level 2 Products
ASA_WVW_2P: ASAR Wave Mode Wave Spectra
ASAR Glossary Terms
Sea Ice Glossary
Land Glossary
Oceans Glossary
Geometry Glossary
ASAR Instrument Glossary
Acronyms and Abbreviations
ASAR Frequently Asked Questions
The ASAR Instrument
Instrument Characteristics and Performance
Inflight Performance Verification
Preflight Characteristics and Expected Performance
Instrument Description
Internal Data Flow
ASAR Instrument Functionality
Payload Description and Position on the Platform
ASAR Products and Algorithms
Auxiliary Products
Common Auxiliary Data Sets
Auxiliary Data Sets for Level 1B Processing
Summary of Auxiliary Data Sets
Instrument-specific Topics
Level 2 Product and Algorithms
Level 2 Product
ASAR Level 2 Algorithms
Level 1B Products
ASAR Level 0 Products
Level 0 Instrument Source Packet Description
Product Evolution History
Definitions and Conventions
Organisation of Products
ASAR Data Handling Cookbook
Hints and Algorithms for Higher Level Processing
Hints and Algorithms for Data Use
ASAR Characterisation and Calibration
The Derivation of Backscattering Coefficients and RCSs in ASAR Products
External Characterisation
Internal Calibration
Pre-flight Characterisation Measurements
ASAR Latency Throughput and Data Volume
Data Volume
Products and Algorithms Introduction
Child Products
The ASAR User Guide
Image Gallery
Further Reading
How to Use ASAR Data
Software Tools
How to Choose ASAR Data
Special Features of ASAR
Geophysical Coverage
Principles of Measurement
Scientific Background
Geophysical Measurements
ASAR Product Handbook
ASAR instrument characterization data
Wave Mode processing parameters
ASAR processor configuration data
Main Processing parameters
ASA_WVI_1P: ASAR Wave Mode SLC Imagette and Imagette Cross Spectra
Product Terms
RADAR and SAR Glossary
Level 1B Products
Summary of Applications vs Products
Site Map
Frequently asked questions
Terms of use
Contact us


2.3 Definitions and Conventions

2.3.1 Definitions Global and Regional Coverage

Depending upon the instrument and operating mode, ENVISAT products may be either Global or Regional. A global product contains coverage for the entire length of an orbit. A regional product may only cover a specific segment of an orbit. Auxiliary Data

Auxiliary data is defined as all other data required for the processing of a product which is not part of the primary measurement data received from the instrument while in the nominal measurement mode. Auxiliary data may come from the satellite itself, sources external to the ADS, or be created by instrument processing facilities within the ADS A comprehensive description of the Auxiliary Products is provided in the section entitled "Auxiliary Products." 2.9. Geolocation and Geocoding

Geolocation information is provided in the product header in the form of latitude and longitude information that allow the user to determine the area covered by the data from a simple inspection of the header. For image data, a geolocation grid may also be provided as an auxiliary data set in the product to allow for precise pixel geolocation.

Some image products may also be geocoded, which is the process of resampling the data to conform to a standard map projection with known coordinates. Product Confidence Data

Product Confidence Data provides an evaluation of the overall quality of the product. As such, it is an evaluation of the product statistics as reported by various pieces of equipment and processors in the processing chain. Product confidence data is thus best represented by evaluating product statistics against predetermined thresholds to determine if the product meets the minimum quality requirements defined by the thresholds. If a product does not measure up to the predefined quality level, the error threshold is exceeded and a flag is set. (See also the section "Level 1B Essential Product Confidence Data." )

  • PCD in the MPH

    The MPH is a generic header (i.e., instrument unspecific), and so any product confidence data (PCD) contained within must be applicable to all instrument types.

    PCD applications include:

    • summary quality; high-level quality indicator for product
    • acquisition and de-multiplexing; this is related to the data commutation and downlink performance aspects which are independent of product type

    PCD in the SPH

    The PCD in the SPH may only contain information pertaining to the entire product length and relates to the execution of the product generation command (since a product will be generated by a single command). Examples include:

    • arithmetic error during product generation
    • auxiliary data files available/used during processing
    • mode usage statistics during orbital revolution
    • time relations used (predicted or precise)

    PCD in the DSR

    The PCD in the DSR, which was called Measurement Confidence Data (MCD) in ERS is referred to as PCD in the ENVISAT payload data segment. The DSR PCD provides details on individual source packet quality. It is related directly to the engineering aspects and details of the ground processing algorithms. Calibration

Calibration data is classified as auxiliary data within the ADS

Internal calibration 2.11.3. data, contained within the instrument source packet, is used during the product generation process. The internal calibration information is generated by the instrument itself during the nominal measurement mode, or as part of a dedicated calibration mode.

External calibration 2.11.4. data, generated by on-ground or orbit calibration activities, is also used during the product generation process. The external calibration data is measured on ground, before launch, or in orbit during the commissioning phase or during periodic calibration activities. Processed Product Sizes and Coverage

The Maximum Size of any product will be the smallest of:

  • Data from a full orbit (100 minutes + potentially 10%, depending on OBR tape dump and specific acquisition downlink timing),
  • Or, data from maximum continuous processed instrument/mode on-time (e.g., ASAR stripline [IM, AP, and WS modes] = 10 minutes),
  • Or, the amount of data to fill a 2 Gbyte file. (In order to use standard UNIX file system capabilities, this limitation may be adjusted or removed as extended file sizes are fully supported.) If the amount of data is greater than 2 GBytes, the product is contained in multiple files, each no larger than 2 GB and each having its own MPH and SPH.
The Minimum Coverage of any product will be the size of a scene specified by ESA for selected imagery sensors (nominal sizes specified):
  • ASAR IM/AP 100 km * 56 km (it may be larger (up to 100 km) for different swath choices)
  • ASAR WS or GM 400 km * 400 km