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AATSR Data Formats Products
SST record 50 km cell MDS
BT/TOA Sea record 17 km cell MDS
Vegetation fraction for Land Surface Temperature Retrieval GADS
Topographic Variance data for Land Surface Temperature Retrieval GADS
Land Surface Temperature retrieval coefficients GADS
General Parameters for Land Surface Temperature Retrieval GADS
Climatology Variance Data for Land Surface Temperature Retrieval GADS
Level 0 SPH
Level 0 MDSR
Auxilliary Data SPH with N = 1
1.6 micron nadir view MDS
Summary Quality ADS
Scan pixel x and y ADS
Grid pixel latitude and longtitude topographic corrections ADS
Across-track Band Mapping Look-up Table
Configuration Data GADS
Processor configuration GADS
LST record 50 km cell MDS
Distributed product MDS
Level 2 SPH
10-arcminute mds
Limits GADS
Validation Parameters GADS
BT/TOA Land record 17 km cell MDS
General Parameters GADS
Temperature to Radiance LUT GADS
Radiance to Brightness Temperature LUT GADS
Medium/High Level Test LUT GADS
Infrared Histogram Test LUT GADS
11 Micron Spatial Coherence Test LUT GADS
11/3.7 Micron Nadir/Forward Test LUT GADS
11/12 Micron Nadir/Forward Test LUT GADS
Characterisation GADS
Browse Day_Time Colour LUT GADS
Browse SPH
Grid pixel latitude and longtitude topographic correction ADS
Level 2 SPH
Auxilliary Products
ATS_VC1_AX: Visible Calibration data
ATS_SST_AX: SST Retrieval Coeficients data
ATS_PC1_AX: Level-1B Processing configuration data
ATS_INS_AX: AATSR Instrument data
ATS_GC1_AX: General Calibration data
ATS_CH1_AX: Level-1B Characterization data
ATS_BRW_AX: Browse Product LUT data
Level 0 Products
ATS_NL__0P: AATSR Level 0 product
Browse Products
ATS_AST_BP: AATSR browse image
Level 1 Products
ATS_TOA_1P: AATSR Gridded brightness temperature and reflectance
Level 2 Products
ATS_NR__2P: AATSR geophysical product (full resolution)
ATS_MET_2P: AATSR Spatially Averaged Sea Surface Temperature for Meteo Users
ATS_AR__2P: AATSR averaged geophysical product
Frequently Asked Questions
The AATSR Instrument
Instrument Characteristics and Performance
In-flight performance verification
Instrument Description
Internal Data Flow
Instrument Functionality
AATSR Products and Algorithms
Common Auxiliary data sets
Auxiliary Data Sets for Level 2 processing
Instrument Specific Topics
Level 2 Products
Level 1B Products and Algorithms
Level 1B Products
Instrument Pixel Geolocation
The Level 0 Product
Differences Between ATSR-2 and AATSR Source Packets
Definitions and Conventions
Organisation of Products
Relationship Between AATSR and ATSR Products
AATSR Product Organisation
Data Handling Cookbook
Characterisation and Calibration
Monitoring of AATSR VISCAL Parameters
Latency, Throughput and Data Volume
Data Processing Software
Data Processing Centres
The AATSR Products User Guide
Image Gallery
Breakup of the Ross Ice Shelf
Land cover in the Middle East
Typhoon Saomai
Mutsu Bay, Japan
Deforestation in Brazil
Spatially Averaged Global SST, September 1993
Further Reading
How to use AATSR data
Why Choose AATSR Data?
Why Choose AATSR Data?
Special Features of AATSR
Principles of Measurement
Scientific Background
The AATSR Handbook
SST record 17 km cell MDS
Surface Vegetation class for Land Surface Temperature Retrieval GADS
1.6 micron forward view MDS
12 micron nadir view MDS
12 micron forward view MDS
Summary Quality ADS
Surveillance Limits GADS
Master Unpacking Definition Table GADS
1.6 micron Non-Linearity Correction LUT GADS
General Parameters GADS
Thin Cirrus Test LUT GADS
Fog/low Stratus Test LUT GADS
1.6 Micron Histogram
Browse MDS
ATS_CL1_AX: Cloud LUT data
Pre-flight characteristics and expected performance
Payload description, position on the platform
Auxiliary products
Auxiliary Data Sets for Level 1B processing
Summary of auxiliary data sets
Calculate Solar Angles
Image Pixel Geolocation
Level 0 Products
Acquisition and On-Board Data Processing
Product Evolution History
Hints and Algorithms for Higher Level Processing
Data Volume
Software tools
Summary of Applications vs Products
Geophysical Coverage
Geophysical Measurements
Visible calibration coefficients GADS
Level 1B SPH
LST record 17 km cell MDS
Conversion Parameters GADS
12 Micron Gross Cloud Test LUT GADS
ATS_PC2_AX: Level-2 Processor Configuration data
Level 2 Products
Hints and Algorithms for Data Use
BT/TOA Sea record 50 km cell MDS
BT/TOA Land record 50 km cell MDS
Level 2 Algorithms
Signal Calibration
Site Map
Frequently asked questions
Terms of use
Contact us


2.9.3 Auxiliary Data Sets for Level 2 processing

AATSR only uses 2 auxiliary files in its L2 processing. Both L2 auxiliary files are maintained by DEFRA.

Clicking on the links provided will take the reader to the Data Formats section, which contains a description of each field within each data set.

AATSR Level 2 Processor Configuration File (ATS_PC2_AX) 6.5.7.

A single data set containing miscellaneous configuration parameters including brightness temperature thresholds for the AST product and parameters defining the geometry of the averaged product.
Based on requirements of AATSR processor design.
To be optimised as part of AATSR L2 algorithm verification. Unlikely to change beyond this point.

SST Retrieval Coefficients (ATS_SST_AX) 6.5.8.

Used to retrieve full resolution (see section ) and spatially averaged (see section ) SST from L1B BTs. The file contains 3 data sets:
  • Across-track band mapping LUT (defines the relationship between pixel across-track co-ordinate and across-track band number).
  • SST retrieval coefficients (for the 1 km gridded SST retrieval).
  • Averaged SST retrieval coefficients (for the averaged SST retrieval).
The coefficients represent a linear regression of SST on brightness temperature. Regression is based on model brightness temperatures derived from an ensemble of atmospheric profiles using a Radiative Transfer (RT) model. (A)ATSR coefficients are based on the model RADGEN from the Rutherford Appleton Laboratory. See below for further details.
Infrequent. As these coefficients are derived on the basis of RT modelling and are not subject to empirical adjustment, any changes to this file will be the result of a new RT calculation. Such an exercise might be undertaken to apply new physical parameters or modelling as the result of detailed product validation.

LST Retrieval Coefficients (ATS_LST_AX)

Used to retrieve full resolution LST from L1b BTs. The file contains 6 data sets comprising a short GADS of general parameters, four LUT GADS of vegetation class, vegetation fraction, climatology and topographic variance data, and one LST Retrieval Coefficient LUT GADS:
  • General Parameters for LST Retrieval
  • Index Data for LST Retrieval
  • Vegetation Fraction for LST Retrieval
  • Climatology Records for LST Retrieval
  • Topographic variance flag for LST retrieval
  • LST Retrieval Coefficients
See Land Surface Temperature Measurement from Space: AATSR Algorithm Theoretical Basis Document, Jan 2002 1.3. .

Generation of Retrieval Coefficient Sets for (A)ATSR

The original ATSR coefficients were based on the work of Zavody et al, 1995 Ref. [1.18 ] , using a scheme with 10 across-track bands. However, they have recently been updated to take account of new developments in coefficient generation, including an improved stratospheric aerosol treatment developed by Merchant et al, 1999 Ref. [1.14 ] , which uses 38 bands to reduce discontinuities at the band edges.

Coefficient derivation involves 3 steps:

  • Generate a statistically representative ensemble of atmospheric profiles;
  • Run radiative transfer model (RADGEN) to derive brightness temperatures for each profile;
  • Derive regression coefficients of surface temperature vs. brightness temperature.

The derivation is therefore dependent on a) the ensemble of atmospheric profiles used, b) the version of RADGEN used, and c) the auxiliary data used in this process.

The recent update to RADGEN was designed to address the following requirements:

  • Ability to read atmospheric profiles derived from ECMWF data

    The original ATSR coefficients were based on a set of 158 radiosonde profiles provided by the UK Met Office. However, Merchant et al introduced a new set of profiles based on ECMWF re-analysis data. Therefore the code had to be modified to accept these new profiles.

  • Enhanced tropospheric aerosol model

    The modifications to the tropospheric aerosol subroutine included the optional implementation of a 'hybrid' scattering model, the addition of asymmetry coefficients (from Shettle and Fenn, 1979) and the removal of redundant scaling. Modifications to the main programme included the optional inclusion of 'constant number density' scaling as alternative to 'constant visibility' scaling, and the introduction of exponential aerosol height distribution, in place of the original distribution, which was uniform below 1 km height.

  • Revised air mass and emissivity definitions to accommodate revised across-track banding scheme

    The original across-track banding scheme used interpolation between 5 standard air mass values computed by RADGEN. The new scheme requires air mass values at swath centre and swath edge in each view.

  • Inclusion of parameterised wind speed effects in the forward view.

    This scheme modifies surface reflectivity and emissivity to account for roughness effects in the forward view (Watts et al 1996 Ref. [1.17 ] ), depending on wind speed.

  • Improved portability of the code.

LST Retrieval Coefficients

The auxiliary file designated ATS_LST_AX contains the look-up tables and retrieval coefficients used by the LST algorithm. It includes the data sets listed in table.

Table 2.34 Data sets included in the LST auxiliary file ATS_LST_AX
Description of data set Contents
General parameters for LST retrieval 3 parameters d, m, NCLASS
Surface type classification 720 x 360 array
Vegetation fraction 720 x 360 x 12 array
Precipitable water 720 x 360 x 12 array
Topographic variance flag 720 x 360 array
LST retrieval coefficients 16 x 2 (vegetation / soil) x 2 (night/day) coefficient sets

The auxiliary files define the surface class and vegetation fraction with a resolution of 0.5 degrees. Thus for each cell of 0.5 degrees in latitude by 0.5 degrees in longitude a surface class and vegetation fraction are defined, that are taken to apply to the whole cell. The arrays are indexed using the latitude and longitude indices lat_index and lon_index defined in Section , and the array values are ordered so that the longitude index varies most rapidly.