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    24-Jul-2014
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SST record 50 km cell MDS
BT/TOA Sea record 17 km cell MDS
ATS_TOA_1P_MDSR_conf
ATS_TOA_1P_MDSR_cl
ATS_TOA_1P_ADSR_pix
ATS_SST_AX_GADSR
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
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
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AATSR Products and Algorithms
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Auxiliary Data Sets for Level 2 processing
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The Level 0 Product
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AATSR Product Organisation
Data Handling Cookbook
Characterisation and Calibration
Monitoring of AATSR VISCAL Parameters
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Throughput
Introduction
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The AATSR Products User Guide
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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
Glossary
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
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Hints and Algorithms for Higher Level Processing
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Summary of Applications vs Products
Geophysical Coverage
Geophysical Measurements
ATS_TOA_1P_ADSR_sa
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
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3.2.2 In-flight performance verification

3.2.2.1 Commissioning

AATSR undergoes commissioning shortly after launch which brings the instrument through to nominal operations. As part of this, a number of performance checks are carried out and the instrument operation is optimised. AATSR commissioning includes initial verification of the operation of the instrument and an optimisation phase. Details of commissioning are contained in the AATSR Commissioning Plan Ref. [1.1 ] , but, in summary, the following major optimisation steps are performed after initial verification of AATSR's operation:

  • Optimisation of the coolers' operating configuration;
  • Checkout of the scan mechanism, in particular, assessment of 'jitter';
  • A Black Body cross-over test, during which the radiometric signals from each blackbody when they are at the same temperature are compared to make an estimate of the relative accuracy. Any significant difference in signal would imply a drift in the temperature sensors' calibration or change in emissivity.
  • Checks of thermal stability of important items;
  • The pixel map will be optimised and the instrument's optical alignment will be verified by checking the positions of the edges of clear views of the earth views and calibration targets;
  • The gains and offsets for the visible and 1.6 µm channels will be optimised to ensure that the dynamic range fully covers the darkest and brightest likely scene types;
  • The operation of the auto gain-offset loop will be optimised;
  • The performance of AATSR's low gain mode will be tested;
  • The source packets will be checked for anomalies (this will identify problems in the instrument or the ground processing transcription);
  • After optimisation of the main subsystems, science data will be analysed to assess the performance of the signal channels. Checks will be made on the radiometric noise, dynamic range, digitisation 3.2.1.4. and stability 3.2.1.5. to verify that the performance is acceptable;
  • The initial performance of the VISCAL unit will be assessed by analysing science data to check that the signal from the unit at full solar illumination agrees with expected levels, the diffuser is uniformly illuminated and the signal is stable.
  • Science data will be examined to investigate any evidence of stray light contamination in-flight;
  • The receipt of blanking pulses and any effect on AATSR data from the RA-2 and the Advanced Synthetic Aperture radar (ASAR) instruments will be tested.

Further testing may be required during the remainder of the commissioning phase dependent upon the results of the above activities.

3.2.2.2 Routine Verification

The performance of the instrument will continue to be assessed during routine operations throughout the duration of the mission. Routine monitoring will include assessment of daily and long term housekeeping trend plots, monitoring the scan mechanism, Black Body, VISCAL, signal channel (radiometric noise, dynamic range and digitisation 3.2.1.4. ) and cooler performance, Level 0 2.5.4.1. data quality checks and production of regular reports on instrument health (Information on the instrument status and performance will be made available to users on the AATSR Engineering Data System web site, accessible from the AATSR Operations website) .

More details of verification are contained in the AATSR Verification Plan Ref. [1.9 ] .

The specific topic of outgassing is discussed in more detail below, as this affects data availability.

3.2.2.2.1 Outgassing

Some water and other materials are inevitably carried into space with the satellite, so when the IRFPA is cooled there will be a build up of condensation affecting the cooler performance and the optical throughput. It will be necessary to warm the IRFPA periodically to allow the condensate to evaporate and thus allow the instrument performance to recover.

From experience of ATSR-1 and ATSR-2, the frequency of outgassing is likely to be:

  • 2-3 weeks after the initial cool down;
  • 3 months after, depending on condensation rates;
  • 6 months thereafter.

In practice, most out-gassings on ATSR-1 and ATSR-2 occurred opportunistically when the instrument was forced into standby mode (and hence for the IRFPA to warm up) due to a platform or payload anomaly, and therefore it has only been necessary to perform a few scheduled outgassings.

During a scheduled outgassing, the instrument will still be operating, but with the IRFPA above its nominal working temperature, and although no useful data will be available from the IRFPA channels (i.e. the 1.6 µm, 3.7 µm, 11 µm and 12 µm), data will be available from the visible channels (i.e. the 0.55 µm, 0.66 µm and 0.87 µm channels). However, there is a caveat over the calibration of the VFPA channels which applied to the products during outgassings and this is discussed in of the User Guide.