SCIAMACHY: The new Level 0-1 ProcessorGunter Lichtenberg1 Sander Slijkhuis1 Bernd Aberle1 Denis Scherbakov1 Markus Meringer1 Stefan Noel2 Klaus

Bramstedt2 Patricia Liebing 2 Heinrich Bovensmann2 Ralph Snel3 Mathijs Krijger3 Richard van Hees3 Pieter van derMeer3 Christophe Lerot4 Angelika Dehn4 Thorsten Fehr5

1Remote Sensing Technology Institute (IMF), German Aerospace Center (DLR), Oberpfaffenhofen, Wessling, Germany2Institute of Environmental Physics (IUP), University of Bremen, Bremen, Germany

3SRON, Netherlands Institute for Space Research Utrecht 4Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium5ESA-ESRIN, Via Galileo Galilei, Casella Postale 64, Frascati, Rome, Italy

6ESA-ESTEC, Keplerlaan 1, Noordwijk, The Netherlands

Introduction

Level 0-1 processing provides calibrated radiances. The calibration ofthe data is done with a combination of on-ground thermal vacuum andambient measurements and in-flight measurements. Currently version9 of the processor is implemented. The Level 1 products with theupdates shown here will be released in 2017 after thouroughly testingthe changes on the basis of retrieval results. For details of the newLevel 2 processor see ATMO-37 - New Developments in theSCIAMACHY L2 Ground Processor

Updated Degradation Correction

The degradation correction isbased on a scan mirror modelthat fits the thickness of con-taminant layers. The scanmirror model was first imple-mented in Version 8 of theprocessor. In version 9 sev-eral improvements were addedthat lead to a better correc-tion of the optical bench degra-dation. Together with the re-calculated polarisation and ra-diometric calibration data fromon-ground measurements it isexpected that the calibrated ra-diances will be improved overthe whole mission life time.Details Poster ATMO-26 - Mir-ror Contamination in Space:On-ground SCIAMACHY mod-elling

Figure 1: Top: Measured and mod-eled degradation of SCIAMACHY at350 nm for 4 different lightpaths:Subsolar, limb, extra mirror and dif-fuser, from left to right over 9 yearsof data. Bottom: Ratio of measuredand modelled m-factors at 350 nm.(SRON)

Better Pointing Correction

I Limb and occultation retrievals need very accurate pointing informationfor proper tangent heights.

I First update of mispointing parameters was already applied in 2007.I IUP fitted new correction parameters by adjusting calculated solar and

lunar positions to measured ones.I For the first time, lunar measurements have been utilized for this

purpose. Details at poster ATMO-30, Bramstedt et. al.

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Figure 2: Elevation and azimuth angle offsets. OLD: Mispointing withthe current processor. NEW: Remaining mispointing with the improved

pointing parameters (IUP).

Improved Polarisation Correction

The polarisation correction for V. 9of the processor will be improvedby implementing several additionsand revisions to the polarisationcorrection:I Implementation of the CHEOPS

correction already used in GOME-1 fora better correction in the UV

I Addition of a retarder matrix to thescan mirror model to consistentlyhandle the phase shift that is causedby the OBM of SCIAMACHY

I Better handling of anomalous PMDdata (spike filtering and electronicdelays)

I Better handling of cases where Ucannot be measured because ofinsufficient instrument sensitivity

I Complete Revision of the Limbpolarisation calculation

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Figure 3: Plot of determinedLimb polarisation values q (top),u (bottom) vs single scatteringvalues for the old (left) and new(right) algorithm (IUP).

Improvements to SWIR Channel Calibration

I Bad Pixel Mask based on Individual Pixels: The new algorithmanalyses each pixel individually over time to decide if it still useful

I Better Dark CorrectionI Spectral Calibration

I SRON derived new polynomial coefficients for the calibration of channel 8I For channel 6 (Methane) a new adaptive scheme for spectral calibration is

investigated.

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Figure 4: Prediction and measurement of the orbital variation of thedark signal in channel 8 (SRON).

New Level 1 Product Format

I Both products, Level 1 and Level 2 will be transferred from the currentENVISAT format to netCDF V4 format

I Guidelines:I Product structure will be as far as possible similar to those developed for Sentinels

(SCIAMACHY is more complicated though)I All information in the current product will also be in the new productsI Level 1 will additionally contain all relevant operations information for LTDPI The geolocation will be available for all pixels (the ENVISAT format required users

to caclulate the coordinates from the provided fine grid)

Further Information

I Level 0-1c ATBD: http://atmos.caf.dlr.de/sciamachy/documents/level 0 1b/scia01b atbd master.pdf (will soon be updated for Version 9)I Gottwald, Manfred, and Heinrich Bovensmann, eds. SCIAMACHY – Exploring the changing Earth’s Atmosphere. Springer Science & Business Media, 2010.