M-Factors
SCIAMACHY
SCIAMACHY M-factors
Introduction
Short-Term Concept
Long-Term
Concept Data
References
Contact
This is the SCIAMACHY m-factors main page.
M–factors are used in the 0-1b processor to compensate for the
radiometric degradation of SCIAMACHY. In
general, an m-factor is defined as the ratio between a measured
spectrum of a constant light source (typically the sun) at a certain
time to a spectrum obtained for the
same optical path at a reference time. M-factors therefore provide an
end-to-end degradation correction for each individual light path.
Schematic view of the different SCIAMACHY monitoring light paths.
M–factors have an impact on the polarization correction and on the absolute radiometric calibration.
The m–factors for the science detectors are multiplicative factors to the absolute radiometric calibration of SCIAMACHY.
The m–factors for the PMDs influence in a non-linear way the polarization correction of SCIAMACHY.
Regarding the m–factors for the polarization requires re-processing of the full mission, as the calculation of the polarization correction has to be done by the Level 0-1b processor.
The concept for calculation and provision of m-factors foresees two steps:
SCIAMACHY long-term monitoring results based on partly calibrated Level 0 data are also available.
The m-factor impact on polarization correction is neglected within the
short–term solution.
The m–factors are provided by an external database, which than can be applied by a modified Level 1b-1c applicator.
Advantages of this approach are:
On long-term, a full set of m-factors including PMDs can be
set up. For this concept, changes of the Level 0-1b processor are
necessary.
The m-factors are included in the Level 1 product and cannot be switched off, if polarization correction or absolute radiometric calibration is needed.
Advantage of this approach is full consistency for reprocessed products.
Currently only m-factors for the
short-term solution are available.
Click here to download the data base.
If you are interested in more information on SCIAMACHY m-factors
contact Stefan
Noël or Klaus Bramstedt.
Author of this page: Stefan Noël
©2008
This is the SCIAMACHY m-factors main page.
Introduction
M–factors are used in the 0-1b processor to compensate for the
radiometric degradation of SCIAMACHY. In
general, an m-factor is defined as the ratio between a measured
spectrum of a constant light source (typically the sun) at a certain
time to a spectrum obtained for the
same optical path at a reference time. M-factors therefore provide an
end-to-end degradation correction for each individual light path.Schematic view of the different SCIAMACHY monitoring light paths.
M–factors have an impact on the polarization correction and on the absolute radiometric calibration.
The m–factors for the science detectors are multiplicative factors to the absolute radiometric calibration of SCIAMACHY.
The m–factors for the PMDs influence in a non-linear way the polarization correction of SCIAMACHY.
Regarding the m–factors for the polarization requires re-processing of the full mission, as the calculation of the polarization correction has to be done by the Level 0-1b processor.
The concept for calculation and provision of m-factors foresees two steps:
- A short-term solution where only science detector readouts are corrected.
- A long-term solution where all light paths are corrected.
SCIAMACHY long-term monitoring results based on partly calibrated Level 0 data are also available.
Short-Term Concept
The m-factor impact on polarization correction is neglected within the
short–term solution. The m–factors are provided by an external database, which than can be applied by a modified Level 1b-1c applicator.
Advantages of this approach are:
- The application of m-factors can be switched on and off by the Level 1 data users.
- M-factors are decoupled from the operational 0-1b processing, therefore a fast implementation is possible.
- Updates of the m-factor data base are possible independent
from a Level 1 re-processing.
Long-Term Concept
On long-term, a full set of m-factors including PMDs can be
set up. For this concept, changes of the Level 0-1b processor are
necessary. The m-factors are included in the Level 1 product and cannot be switched off, if polarization correction or absolute radiometric calibration is needed.
Advantage of this approach is full consistency for reprocessed products.
Data
Currently only m-factors for the
short-term solution are available.
Click here to download the data base. References
- K. Bramstedt, Calculation of SCIAMACHY M-Factors, Technical Note, IFE-SCIA-TN-2007-01-CalcMFactor, Issue: 1, 2008. (PDF file, ca. 1.3 MB)
Contact
If you are interested in more information on SCIAMACHY m-factors
contact Stefan
Noël or Klaus Bramstedt.
Author of this page: Stefan Noël
©2008