Degradation correction V10      Download      M-Factors V6.x/V7.x       References       Contact


This is the SCIAMACHY m-factors main page. This page refers to the SCIAMACHY Level 0-1b processor version 10.

Degradation correction L1B Version 10

With version 8 onwards of the Level 0-1b processor, a new common approach for the radiometric calibration (including polarisation correction) and the degradation correction of SCIAMACHY has been introduced.
For the calculation of polarisation and radiance response we start with the following formula, which describes the light by a Stokes vector and the instrument by a series of matrices. 

with:
   the Stokes vector of the light in front of the detector,

  the Stokes vector for the incoming light,
  the radiance sensitivity of the OBM,
  the polarisation sensitivity of the OBM,
  the Mueller matrix of the scanner unit.
The Mueller matrix of scanner unit depends on the scanner angle of the ESM mirror, the scanner angle of the ASM mirror or the sun elevation angle (depending on the light path in the instrument). This Mueller matrix is based on a physical model, which describes the reflections on the mirrors or the diffuser surfaces using the Fresnel equations. The model includes a contamination layer on top of the optical surfaces. The thicknesses of these contamination layers are derived from the regular measurements of the different monitoring light pathes.

The derived thicknesses describe to a large extend the radiometric degradation of the instrument with time.

The remaining degradation is then described by a residual m-factor (OBM m-factor in the above equation), mainly describing the degradation of the optical bench module (OBM).
This degradation correction is now integrated in the Level 0-1b processor as part of the radiometric calibation, i.e. calibrated SCIAMACHY spectra of version 8 or higher are always degradation corrected.
The physical details of the scanner model are described in Krijger et. al., the implementation for the degradation correction is descibed in this technical note.

The scanner model and the calculation for the m-factors have been revised for L1b Version 9 (not published).

The application of the m-factors has been revised again vor L1B Version 10, released in July 2024.

Download m-factor files V9.14

The m-factor files V9.14 (containing the derived thicknesses of the contamination layers, the used refractive indicees, the OBM m-factors, and the residual m-factors in a binary format) are used by the L0-1b processor Version 10 and usually not relevant for the users of SCIAMACHY data. These files are stored here for reference only (m-factor_09.14_20161229.tgz, 878 MB).
The m-factor files V9.14 were also used by the L0-1b processor Version 9. Version 9 was not published.

Download m-factor for V8.31

The m-factor files V8.31 (containing the derived thicknesses of the contamination layers, the used refractive indicees and the residual m-factors in a binary format) are used by the L0-1b processor Version 8.x and usually not relevant for the users of SCIAMACHY data. These files are stored here for reference only (m-factor_08.31_20130830.tgz, 735 MB).

M-Factors V6.x/V7.x

The Level 0-1b processor V6.x/V7.x degradation correction is an end-to-end correction with the so-called monitoring factors (m-factors). This approach is described on the V6.x/V7.x m-factor pages, including download possibilities for the m-factor files.

References

• K. Bramstedt, Scan-angle dependent degradation correction with the scanner model approach, Technical Note, IUP-SCIA-TN-Mfactor, Issue: 1, 2014.
• Krijger, J. M., Snel, R., van Harten, G., Rietjens, J. H. H., and Aben, I.: Mirror contamination in space I: approach, Atmos. Meas. Tech. Discuss., 7, 1213-1246, doi:10.5194/amtd-7-1213-2014, 2014.

Contact

If you are interested in more information on SCIAMACHY m-factors contact Stefan Noël or Klaus Bramstedt.

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Author of this page: Stefan Noël
       
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