March 23, 2015

IASI FM2 In-Flight Commissioning

In-Flight Commissioning at CNES (TEC)

The IASI instrument in orbit commissioning includes 2 phases. The first one is the functional validation which is dedicated to the verification of the good behaviour of the instrument. The second one is the CAL/VAL phase (calibration/validation) which concerns the detailed performance characterisation, the validation of the measurement with comparison with others instruments and the tuning of the data processing parameters.

    The IASI system In orbit verification was ended successfully by a MetOp-A In-orbit Verification campaign review held on March 28 and 29.

      Functional Validation (10/2006 - 01/2007)

       Ice contamination
       First IASI spectra located on a IIS image computed from IASI. 

        Calibration / Validation

        The CAL/VAL includes 3 steps:
        The step A is dedicated to a preliminary characterisation of the geometrical, radiometric and spectral performances of the instrument.

        More specifically, the activities performed during the Phase A were mainly dedicated to:

        • Determine the level of monitoring thresholds that allow the instrument and its processing to continue to behave nominally in spite of external perturbations (e.g. spikes).
        • Optimize the parameters of the on-board and Level1 processing in order to achieve the required performance.
        • Determine small modifications of the Level1 processing to improve its behaviour with real data (mainly error handling).
        • Validate these modifications and characterise the performance.
        • Verify on a daily basis the behaviour of all the processing chain (on-board and on-ground). This activity is of course performed with a lot of support from the operational IASI TEC (Technical Expertise Center) team.

        During this phase the following tasks were carried out:

        • L0 Data Quality monitoring performed by DPS (digital processing system) and monitored by TEC (1st level)

        Failure Detection criteria for DPS processing verified by TEC and uploaded in DPS
        Flags generated by DPS, if any, explained
        Level 0 Data Quality monitored by TEC

          • Full Resolution, fully navigated AVHRR products available in TEC
          • L1 spectra & images computed by OPS (Operational Processing software) at TEC (TEC version) (functional test)

          Optimized coding tables installed in OPS-TEC
          Spectral Data Base and other parameters computed pre-flight in OPS-TEC
          IIS processing chain working and monitored by TEC
          Spectral Calibration working and monitored by TEC
          Filtering process working and monitored by TEC
          L1 spectra processing (1A, 1B & 1C) working
          Coregistration IIS/AVHRR working and monitored by TEC
          AVHRR Radiance analysis working and monitored by TEC
          IIS (IASI Integrated imager)Radiance analysis working and monitored by TEC
          Localisation of IASI product working and monitored by TEC

          • L1 Product Quality monitoring performed by OPS/TEC (1st step)

          Failure Detection criteria for OPS processing verified by TEC and uploaded in OPS-TEC software
          Flags generated by OPS, if any, explained

          • First assessment of IASI Performance (on limited amount of data)

          Non Linearity correction table computed by TEC and uploaded in DPS
          Band Merging, Band Limits optimized and uploaded in DPS
          Contamination rate by water ice assessed
          Residuals of the on-board radiometric calibration analyzed by OPS
          Interband radiometric calibration errors assessed on earth targets and SM cal. views
          Interpixel radiometric calibration errors assessed on earth targets
          IIS-AVHRR co-registration assessed
          IIS-sounder co-registration assessed
          Homogeneity of IIS/Sounder radiometric calibration assessed
          Sounder IPSF (Instrument point spread function) checked (approximately)
          Radiance spatial distribution in sounder FOV validated
          Cube Corner Offset stability checked
          Operational spectral calibration in B3 verified (stability assessed)

          Spectral calibration homogeneity in interbands B1/B2 and B2/B3 verified
          Spectral calibration in B1 & B2 bands validated (approx.)
          Level of micro-vibrations assessed
          Navigation of the products validated
          Line of sight short term stability assessed

          • Archive some data necessary for long term evaluation in phase B and phase C

          All opportunities for simultaneous measurements with other sounder (AIRS,TES,...)
          All the situations when moon path is close to CS1 or CS2

          • Configuration parameters for DPS and Level 1 processing updated for Phase B

          The philosophy of this Cal/Val phase, the description of the main events and table of tasks is given.

          According to the results of SIOV and Cal/Val Phase A:

          • the IASI Level 1 PPF version was upgraded to 3.6.6 on Thursday 22 March 2007 (11:54 UTC)
          • the on board and on-ground parameters were updated on Monday 2 April 2007 (13:10 UTC)

          A product review board is planned by the end of April. IASI level 1c distribution to all users should be decided.

          The step B dedicated to a detailed characterisation of the above parameters has started from March 28. It will last about 8 weeks.

          The in-depth validation of the instrument performances will be verified during the step C.

          The Cal/val phase A has been completed at te beginning of April and was immediatly continued with the phase B the end of is estimated around June 22.