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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


2.9.1 Summary of Auxiliary Data Sets Auxiliary Data Files

Auxiliary data files are all other data files used to produce a product other than the direct measurements of the instrument. This may include calibration data that was measured on-board but is not part of the main measurement data of the instrument. It may also include external calibration files from sources other than the satellite, processor configuration files, and any other files needed by instrument processors. For a further discussion of the auxiliary data files refer to the section "Common Auxiliary Data Sets" 2.9.3. and "Auxiliary Data Sets for Level 1B Processing" 2.9.2. Naming Strategy

The naming strategy for auxiliary data will be similar to the product naming conventions. The first 10 characters will be the auxiliary data ID, and will follow the following format:


WWW is the same instrument codes used for specifying product IDs. The instrument ID for auxiliary data indicates the instrument the data is intended for. Auxiliary data intended for several instruments will use the code AUX.

XXX is used to identify the type of auxiliary data.

YZ is always set to the letters AX for auxiliary data.

For auxiliary data, the file name structure contains:

The Auxiliary Data ID as described above (10 characters).

The Processing Stage flag which is used to indicate the quality level of the auxiliary data, using the same method as for the core products with N for preliminary quality up to V for highest quality (1 character).

The Originator ID indicates the source of the auxiliary data (3 characters). If not relevant, set to XXX.

The date and time of the auxiliary data creation (YYYYMMDD_hhmmss) (15 characters).

Underscore character (1 character).

The date and time when the auxiliary data becomes valid in the PDS (YYYYMMDD_hhmmss) (15 characters).

Underscore character (1 character).

The date and time when the auxiliary data ceases to be valid in the PDS (YYYYMMDD_hhmmss) (15 characters).

Note: The filename format above is 61 characters long. When the filename is written to field 1 of the MPH (which is 62 characters long) a blank space character is added at the end of the filename in order to fill the field.

Table 2.67 below provides a list of the auxiliary data files used in the ENVISAT PDS for ASAR processing.

Table 2.67 ENVISAT PDS Auxiliary Data Files used by ASAR
Approx. Size (MB)
Estimated Update Rate
Used by
Used for Comments
L1B ASAR Processor Configuration file
L1B Instrument characterisation file
6 Months
L1B ASAR External calibration data
6 Months
L1B ASAR External characterisation data
1 Day
All Instruments
L0, L1B, L2 Restituted orbit state vector
1 Day
L0, L1B, L2 Predicted orbit state vector
1 day
All Instruments
L1B DORIS Preliminary Orbit State Vectors
1 day
All Instruments
L1B DORIS Precise Orbit State Vectors Auxiliary Data Structure

Auxiliary data files follow the same format guidelines as the PDS products. Every Auxiliary Data file will consist of an MPH, an SPHand one or more data sets.

Auxiliary data which originates outside the PDS will be wrapped in an MPH and SPH upon entry to the PDS. The actual contents of the foreign file will become those of a GADS, without modification. Auxiliary Data MPH

The MPH used for auxiliary data is the same as that used for products. For auxiliary data which originates from the satellite, most of the MPH fields will be relevant. For auxiliary data which does not originate from the satellite, many sections of the MPH will not be relevant, and MPH fields not pertinent will be blanked or set to zero (depending on the field type) as shown in the MPH layout provided in the Data Formats 6.6.1. section.

Field 1 of the MPH will contain the name of the auxiliary data file using the auxiliary data naming strategy described in NAMING STRATEGY above. Therefore, field 1 of the MPH will be constructed as follows:

Table 2.68 Field 1 of Auxiliary Data MPH Record
Field Description Units Byte Length Data Type
keyword 8 8*uc
quotation mark (") 1 uc
Auxiliary Data File Name (the following fields describe the contents of the auxiliary data filename) 62
10 character file ID - 10 10*uc
Processing stage flag - 1 uc
Originator ID (if not relevant, set to XXX) - 3 3*uc
creation_day (YYYYMMDD UTC creation day of the auxiliary file) - 8 8*uc
underscore character - 1 uc
creation_time (HHMMSS UTC creation time of the auxiliary file) - 6 6*uc
underscore character - 1 uc
valid_day (YYYYMMDD UTC day the auxiliary file becomes valid) - 8 8*uc
underscore character - 1 uc
valid_time (HHMMSS UTC time the auxiliary file becomes valid) - 6 6*uc
underscore character - 1 uc
invalid_day (YYYYMMDD UTC day the auxiliary file becomes invalid) - 8 8*uc
underscore character - 1 uc
invalid_time (HHMMSS UTC time the auxiliary file becomes invalid) - 6 6*uc
blank space character - 1 uc
quotation mark (") - 1 uc
newline character terminator 1 uc Auxiliary Data SPH Structure

The structure of this header file is given in Data Formats.(Chapter 6. ) Auxiliary Data Sets

The Data Sets may be of any of the types described for PDS Products, and follow identical format rules. Any exceptions are noted in the individual file descriptions.