page 1 envisat validation workshop, acvt-gbmcd, sciamachy scient. prod. 12/12/2002 envisat...
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Page 1Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY scient. prod. 12/12/2002
Envisat Validation Workshop
Atmospheric Chemistry Validation Team
Ground-Based Measurements and Campaign Database Subgroup
Comparison of scientific SCIAMACHY products with ground-
based measurementsKlaus Bramstedt [email protected]
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Scientific productsNon-operational algorithms for determining atmospheric parameters
in the scientific community.
Use:
Verification
Products not available yet
New products
Feedback for operat. products
Limitations:
0-1 processing/calibration
availability of Level 1 products
"non-operational“
Only preliminary case studies
Examples: - NO2 col. - CH4/CO col. - Ozone profile (limb) – PMC detection
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Scientific NO2 columns DOAS (ife, University of Bremen, A. Richter)
Pacific radiance used as reference spectrum in DOAS fit
Compared with: Groundb.
DOAS Ny Alesund Bremen Nairobi(AO 331, A. Richter)
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Comparison of CH4 and CO
WFM-DOAS (M. Buchwitz, IUP/ife Bremen) Reference spectra are derivatives of the radiance, fit
parameter is VCD Additional „Calibration Correction Function“ fitted
Iterat. maxim. likelihood method (H. Schrijver,SRON) Modelled spectrum is fitted to the measured spectrum.
Compared with: FTIR
Ny-Alesund (AO 331, A. Schulz) Kiruna (AO 191, T. Blumenstock)
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Comparison of O3 profiles from limb
Limb ozone profiles (C. von Savigny, IUP/ife Bremen) Normalized, paired limb radiances are analysed with an
optimal estimation approach (OSIRIS)
Compared with: Ozone sondes from:
Ny-Alesund (AO 331, P. von der Gathen) Neumayer (Antarctica) (AO 331, P. von der Gathen) Hohenpeißenberg (AO 158, W. Steinbrecht)
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Ny-Alesund 07.08.02Ny-Alesund 24.07.02
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Neumayer 03.11.02Neumayer 10.10.02
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Hohenpeißenberg 22.11.02Hohenpeißenberg 06.11.02
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Page 19Envisat Validation Workshop, ACVT-GBMCD, SCIAMACHY scient. prod. 12/12/2002
SummaryPreliminary Comparisons: CH4/CO columns: 2 algorithms available
up to 50% dev. (same order of magnitude!!) Ozone Limb profiles: Altitude shift (pointing problem?) NO2 columns: reliable relative and absolute values Antarctic ozone hole identified! PMCs can be detected in limb
All scientific retrievals and their validation suffer from O-1 processing problems (calibration and availability), but:
It´s in there!