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Progress on the unification of the SO 2 retrieval for GOME-2A/B and OMI. C. Hörmann, S. Beirle, K. Mies and T. Wagner First German S5P Verification Meeting Bremen November 28 and 29, 2013. Unification of SO 2 DOAS retrieval.
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Progress on the unification of the SO2 retrieval for GOME-2A/B and OMI C. Hörmann, S. Beirle, K. Mies andT. Wagner First German S5P Verification Meeting BremenNovember 28 and 29, 2013
Unification of SO2 DOAS retrieval -Same DOAS fit properties for all 3 instruments (GOME-2A, GOME-2B, OMI): -Fit range: 312.1-324 nm - Used absorption cross sections: SO2 223K (Bogumil et al.) O3 223K (Bogumil et al.) O3 223K * λadditional O3 cross sections to correct O3 223K ^ 2 for AMF wavelength dependence (Pukite et al., 2011) Ring Inverse reference (straylight correction) - Calibration via single reference spectrum for GOME-2A/B, individual referencespectra for each OMI detector raw
New SO2 DOAS retrieval for OMI Daily de-striping by subtraction of detector raw dependent offset from Pacific reference sector(red orbit stripes on April 1 due to „OMI Zoom Mode“ individual calibration needed?!?)
Daily data: OMI SO2 VCD (geo.) lat. dependent offset still visible eruption of Piton de la Fournaise Substraction of latitudinal dependent offset (calculated for each grid row, i.e. 0.1°)
Daily data: OMI SO2 VCD (geo.) offset corrected
Comparison to GOME-2A SO2 VCD (geo.) Good agreement, only small differences because of different overpass time
Mean latitudinal SO2 VCD(without latitudinal offset correction) GOME-2AOMI Mean SO2 VCD Latitude [°N]
Mean latitudinal SO2 VCD(latitudinal offset corrected) GOME-2AOMI Mean SO2 VCD Latitude [°N]
Monthly mean: OMI SO2 VCD (geo.) iceedgevisible lat. dependentoffsetagainvisible interferencewithtopographyandbrightsurfaces offset corrected
Comparison to GOME-2A SO2 VCD (geo.) lessinterferencewithtopography • Very good agreement • Less interference with topography because of pixel size?
Mean latitudinal SO2 VCD(without latitudinal offset correction) GOME-2AOMI Mean SO2 VCD Latitude [°N]
Mean latitudinal SO2 VCD(latitudinal offset corrected) GOME-2AOMI Mean SO2 VCD Latitude [°N]
GOME-2A vs. OMI (monthly mean) 1:1 slope 1:1 slope 1:1 slope Popocatépetl/Mexico City Nyiamuragira Norilsk(volcanic/anthropogenic) (volcanic) (anthropogenic) • Good agreement between GOME-2A and OMI for monthly mean • Best correlation for Norilsk region probably because of fairly constant emissions
Comparison of GOME-2A vs. GOME-2B dataformatproblem (contact R. Lang) • GOME-2A data quality decreased due to degradation (σ2013 ≈ 2 ∙ σ2007) • due to narrow swath, global coverage after ≈ 4.5 days
GOME-2B SO2 VCD • good agreement (almost same overpass time) • GOME-2B data blurred compared to GOME-2A (larger pixel size)
Mean latitudinal SO2 VCD(without latitudinal offset correction) GOME-2AGOME-2B Mean SO2 VCD strong latitudinal offset (unknown origin) Latitude [°N]
Mean latitudinal SO2 VCD(latitudinal offset corrected) GOME-2AGOME-2B Mean SO2 VCD Very good agreement after latitudinal offset correction Latitude [°N]
GOME-2A vs. GOME-2B (monthly mean) 1:1 slope 1:1 slope 1:1 slope Popocatépetl/Mexico City Nyiamuragira Nevado del Ruiz(volcanic/anthropogenic) (volcanic) (volcanic) • Good agreement between GOME-2A and GOME-2B for monthly mean • Large scatter visible in GOME-2A data
Plans for the near future • Further improving SO2 fit ( especially GOME-2A/B) • Comparison of timeseries/annual maps (e.g. China, Norilsk…) • Evaluation of SCIAMACHY data • Implementation of SO2 DOAS fit at larger wavelengths for OMI • + combination approach + intercomparison GOME-2A/B/OMI • 5) Analysis and comparison of test data (CAMELOT)