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SCIAMACHY: Spectral Calibration in the SWIR Channels

Lichtenberg, Günter and Hamidouche, Mourad and Schreier, Franz and Hochstaffl, Philipp and Meringer, Markus (2016) SCIAMACHY: Spectral Calibration in the SWIR Channels. ACVE 2016 Atmospheric Composition Validation and Evolution, 18-20 October 2016, ESA ESRIN Frascati, Italy.

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SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) is a scanning nadir and limb spectrometer covering the wavelength range from 212 nm to 2386 nm in 8 channels. It is a joint project of Germany, the Netherlands and Belgium and was launched in February 2002 on the ENVISAT platform. After the platform failure in April 2012, SCIAMACHY is now in the postprocessing phase F. SCIAMACHY's originally specified in-orbit lifetime was double the planned lifetime. SCIAMACHY was designed to measure column densities and vertical profiles of trace gas species in the mesosphere, in the stratosphere and in the troposphere (Bovensmann et al., 1999). It can detect a large amount of atmospheric gases (e.g. O3, H2CO, CHOCHO, SO2, BrO, OClO, NO2, H2O, CO, CH4, among others ) and can provide information about aerosols and clouds. The standard spectral calibration of the SCIAMACHY detectors is done with an on-board Spectral Line Source (SLS) by comparing theoretical line positions with line positions retrieved during calibration measurements. However, the used PtCrNe lamp does not have enough strong lines in the SWIR range (channels 6 -8 ) upwards of 1000 nm. The retrieval of in-flight line positions is additionally hampered by many damaged detector pixels of the SWIR detectors. An analysis of the mission data showed that for channels 6-8 no in-flight correction of the on-ground spectral calibration can be done with the standard approach, even at the beginning of the mission with a significant lower number of damaged pixels. We therefore started a study to investigate an alternative spectral calibration approach. In this approach a highly resolved reference spectrum is fitted with a DOAS like algorithm to retrieve the wavelength for each detector pixel. This approach was already tested by us for the Sentinel-4 UVN and the former Earth Explorer 8 candidate mission CarbonSat. For the method to work it is essential to have a good knowledge of the in-flight spectral response function and its change over time. Preliminary results show that the shape of the response function deviates from the current assumption of a Gaussian. For a successful fit it is also necessary to handle the many outliers caused by the bad pixels in an appropriate way. In this paper we present the first results of our investigations, focussing on channel 6 and the methane retrieval window.

Item URL in elib:https://elib.dlr.de/108654/
Document Type:Conference or Workshop Item (Speech)
Title:SCIAMACHY: Spectral Calibration in the SWIR Channels
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Lichtenberg, GünterGuenter.Lichtenberg (at) dlr.deUNSPECIFIED
Hamidouche, Mouradmourad.hamidouche (at) dlr.deUNSPECIFIED
Schreier, FranzFranz.Schreier (at) dlr.deUNSPECIFIED
Hochstaffl, Philippphilipp.hochstaffl (at) dlr.deUNSPECIFIED
Meringer, MarkusMarkus.Meringer (at) dlr.deUNSPECIFIED
Date:18 October 2016
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:SCIAMACHY spectral calibration atmosphere
Event Title:ACVE 2016 Atmospheric Composition Validation and Evolution
Event Location:ESA ESRIN Frascati, Italy
Event Type:Workshop
Event Dates:18-20 October 2016
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Projekt ENVISAT (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Lichtenberg, Günter
Deposited On:30 Nov 2016 17:59
Last Modified:31 Jul 2019 20:05

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