2.9.2 Auxiliary Data Sets for Level 1B processing
All of the following AATSR-specific L1B auxiliary
files will be maintained by the Announcement of
Opportunity Instrument Provider (AOIP), with
the exception of ATS_BRW_AX. This file
will be maintained by ESA.
Clicking on the links provided will take the
reader to the Data Formats section of this
handbook, which contains a description of each
field within each data set.
AATSR L1B Processor
Configuration File (ATS_PC1_AX) 6.5.6.
- Used throughout the L1B processing, this
file consists of a single data set
containing constants and internal instrument
and data processing parameters.
- AATSR processing architecture and instrument
- Optimised during L1B algorithm verification.
Likely to remain unchanged from then on.
Characterisation File (ATS_INS_AX) 6.5.5.
- Used to unpack and validate the AATSR
measurement and auxiliary telemetry, this
file contains 6 data sets:
- General parameters for unpacking
source packet auxiliary data.
- Master Unpacking Definition Table
(MUDT) for unpacking auxiliary data.
- Parameters to convert unpacked
- Parameters to perform limit checks
on the unpacked auxiliary items.
- Surveillance limits for checks on
converted auxiliary items.
- Validation parameters for
specialised checks of converted
- Instrument telemetry definition, instrument
characterisation data and Instrument
Operations Manual (IOM).
- These instrument parameters will be
scrutinised as part of the instrument Switch
On and Data Acquisition Phase (SODAP) test
programme. Once completed, they are expected
to remain relatively stable throughout the
mission. Any changes to surveillance limits
will be identified as part of routine
instrument performance monitoring by the
Flight Operations Support team.
File (ATS_VC1_AX) 6.5.9.
- Contains a single data set of visible
channel calibration parameters.
- New calibration parameters are calculated
and submitted to the PDS once per day based
on the observed signal from the AATSR VISCAL
unit from previous orbits.
- Daily (see section 2.11. for further details).
File (ATS_GC1_AX) 6.5.4.
- Consists of 4 data sets containing
parameters used in the calibration of the
- General parameters for IR calibration
- Temperature to radiance LUT
- Radiance to Brightness Temperature LUT
- 1.6 µm channel non-linearity
- Calculated from instrument characterisation
data, including channel filter profiles and
non-linearity measurements. This process is
discussed further in section 22.214.171.124.2. and section 126.96.36.199.3.
- Verified during AATSR Switch-On and Data
Acquisition Phase (SODAP). Any future
updates are expected to be infrequent.
File (ATS_CH1_AX) 6.5.2.
- A single data set containing several
categories of parameter: instrument
alignment parameters related to the
satellite geolocation model, AOCS and geodetic
constants (e.g. parameters of the reference
ellipsoid) and parameters relating to the
pixel map and regridding. Used primarily for
geolocation and regridding.
- Instrument characterisation data, physical
constants and internal processing parameters.
- Instrument alignment parameters will require
verification in-flight during the SODAP.
Further tuning may be necessary during
algorithm verification. Subsequent updates
will be infrequent. All other data will be
stable prior to launch.
Cloud Test LUTs (ATS_CL1_AX) 6.5.3.
- 9 data sets, containing coefficients and
thresholds for the 9 tests used by the
cloud-clearing algorithm. (Zavody et al, 2000
Ref. [1.19 ]
- 1.6 µm histogram test LUT
- 11 µm spatial coherence test LUT
- 12 µm gross cloud test LUT
- Thin cirrus test LUT
- Medium/high level cloud test LUT
- Fog/low stratus test LUT
- 11/12 µm nadir/forward test LUT
- 11/3.7 µm nadir/forward test LUT
- Infra-red histogram test LUT
- Some tables are based on Radiative Transfer
(RT) modelling. Others are derived on a more
empirical basis by inspection of images.
Many have been passed directly from ATSR-2
For the 2 view-difference tests,
coefficients were fitted to BT data
derived from RT modelling. The
thresholds for these tests
remain the same as for ATSR-2.
Thresholds for the 11/12 micron thin
cirrus test and the medium/high level
cloud test represent an envelope
enclosing the data on a
corresponding scatter diagram. New
thresholds were derived for AATSR by
applying a differential correction to
those in the ATSR-2 table, the
magnitude of which is derived from RT modelling.
All other tables are those used with
ATSR-2. In most of these cases, the
tables for ATSR-1 and ATSR-2 were
identical, and no basis for a
differential correction was identified.
- Certain LUT parameters may be adjusted on an
empirical basis with respect to real data
during the commissioning phase, however
there are no plans for a thorough
review of the AATSR cloud tests. The RT
modelling for cloud clearing is similar to
that required for the derivation of
SST retrieval coefficients. Therefore, any
update to those files requiring RT modelling
is likely to coincide with a new RT
modelling exercise for the SST coefficients.
Browse LUT (ATS_BRW_AX) 6.5.1.
- Colour LUT used during production of the
daytime part of the AATSR Browse product to
convert the 0.67, 0.87 and 11 µm
channel values to values of red, green
- IONIA AVHRR Browser scheme (Melinotte et al,1995
Ref. [1.13 ]
This LUT has been developed to enhance
specific features of the data.
- Infrequent. Most likely during the early
months of the mission, to optimise the
performance of the Browse product. Will
remain stable from that point on.