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
Mar 15, 2016
Progress on the unification of the SO2 retrieval for GOME-2A/B and OMI
C. Hörmann, S. Beirle, K. Mies and T. 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 * λ additional 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°)
offset corrected
Daily data: OMI SO2 VCD (geo.)
Comparison to GOME-2A SO2 VCD (geo.)
Good agreement, only small differences because of different overpass time
GOME-2AOMI
Mean latitudinal SO2 VCD(without latitudinal offset correction)
Latitude [°N]
Mea
n SO
2 VCD
GOME-2AOMI
Mean latitudinal SO2 VCD(latitudinal offset corrected)
Latitude [°N]
Mea
n SO
2 VCD
Monthly mean: OMI SO2 VCD (geo.)
offset corrected
lat. dependent offset again visible
interference with topography and bright surfaces
ice edge
visible
Comparison to GOME-2A SO2 VCD (geo.)
Very good agreement Less interference with topography because of pixel size?
less interference with topography
GOME-2AOMI
Latitude [°N]
Mea
n SO
2 VCD
Mean latitudinal SO2 VCD(without latitudinal offset correction)
GOME-2AOMI
Latitude [°N]
Mea
n SO
2 VCD
Mean latitudinal SO2 VCD(latitudinal offset corrected)
GOME-2A vs. OMI (monthly mean)
Good agreement between GOME-2A and OMI for monthly mean Best correlation for Norilsk region probably because of fairly constant emissions
Popocatépetl/Mexico City Nyiamuragira Norilsk (volcanic/anthropogenic) (volcanic) (anthropogenic)
1:1 slope 1:1 slope 1:1 slope
Comparison of GOME-2A vs. GOME-2B
data format problem (contact R. Lang)
GOME-2A data quality decreased due to degradation (σ2013 ≈ 2 ∙ σ2007) due to narrow swath, global coverage after ≈ 4.5 days
good agreement (almost same overpass time) GOME-2B data blurred compared to GOME-2A (larger pixel size)
GOME-2B SO2 VCD
GOME-2AGOME-2B
Latitude [°N]
Mea
n SO
2 VCD
Mean latitudinal SO2 VCD(without latitudinal offset correction)
strong latitudinal offset (unknown origin)
GOME-2AGOME-2B
Latitude [°N]
Mea
n SO
2 VCD
Mean latitudinal SO2 VCD(latitudinal offset corrected)
Very good agreement after latitudinal offset
correction
GOME-2A vs. GOME-2B (monthly mean)
Good agreement between GOME-2A and GOME-2B for monthly mean Large scatter visible in GOME-2A data
Popocatépetl/Mexico City Nyiamuragira Nevado del Ruiz (volcanic/anthropogenic) (volcanic) (volcanic)
1:1 slope 1:1 slope 1:1 slope
Plans for the near future
1) Further improving SO2 fit ( especially GOME-2A/B)
2) Comparison of timeseries/annual maps (e.g. China, Norilsk…)
3) Evaluation of SCIAMACHY data
4) 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)