sao omi formaldehyde, water vapor and glyoxal retrievals gonzalo gonzalez abad helen wang...
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SAO OMI formaldehyde, water vapor and glyoxal retrievals
Gonzalo Gonzalez AbadHelen Wang
Christopher MillerKelly Chance
Xiong LiuThomas Kurosu
OMI Science Team Meeting 12th March 2014
Summary• Formaldehyde
– Updates to spectroscopy– Slant column fitting– Air mass factor calculation– Reference Sector Correction– Old vs. new SAO H2CO
• Water vapor– Retrieval set up– Results– Early validation
• Glyoxal– Retrieval set up– Results– OMI vs GOME-2
• New L2 files fields and information
H2CO spectroscopy updates
H2CO cross sections High resolution solar spectrum
H2CO spectroscopy updates:O2-O2 collision complex cross sections
H2CO Slant Column FittingFitting window 327.5 – 356.5 nm
Baseline polynomial 3rd order
Scaling polynomial 3rd order
Instrument slit function Hyper-parameterization of pre-flight measurements, Dirksen et
al., 2006
Wavelength calibration Spectral shift (no squeeze)
Solar Reference Spectrum
Chance and Spurr, 1997
HCHO cross sections Cantrell et al., 1990; 300K
O3 cross sections Macilet et al., 1995; 228K
NO2 cross sections Vandaele et al., 1998 220K
BrO cross sections Wilmouth et al., 1999; 228K
Molecular Ring cross sections
Chance and Spurr, 1997
Sampling correction Computed on-line
Residual common mode spectrum
Computed on-line
Fitting window 328.5 – 356.5 nm
Baseline polynomial 3rd order
Scaling polynomial 3rd order
Instrument slit function Hyper-parameterization of pre-flight measurements, Dirksen et
al., 2006
Wavelength calibration Spectral shift (no squeeze)
Solar Reference Spectrum
Chance and Kurucz, 2010
HCHO cross sections Chance and Orphal, 2011; 300K
O3 cross sections Macilet et al., 1995; 228K & 295K
NO2 cross sections Vandaele et al., 1998 220K
BrO cross sections Wilmouth et al., 1999; 228K
O2-O2 collision complex cross-sections
Thalman and Volkamer, 2013
Molecular Ring cross sections
Chance and Spurr, 1997
Sampling correction Computed on-line
Residual common mode spectrum
Computed on-line
Operational New version
H2CO Slant Column Fitting:Orbit #43214
Shared Air Mass Factor Calculation for H2CO, C2H2O2 and H2O
• New lookup tables for scattering weights and TOA radiances calculated with Vlidort 2.4rt
• 5 years OMLER albedo• OMI L1 surface height information• OMCLDO2 cloud information• Cloudy pixels independent pixel approximation• Monthly GEOS-Chem climatology for 2007• 340 nm for H2CO
• 448 nm for C2H2O2
• 455 nm for H2O
H2CO AMF calculation: Orbit 8537 21st February 2006
H2CO AMF calculation: an example of scattering weights
H2CO reference sector correction
Old vs. new SOA H2CO product: Orbit #43214
H2CO time series and L3 comparison: old vs. new SAO retrievals
H2O retrieval set upFitting window 430 - 480 nm
Baseline polynomial 3rd order
Scaling polynomial 3rd order
Instrument slit function Hyper-parameterization of pre-flight measurements, Dirksen at al., 2006
Wavelength calibration Spectral shift (no squeeze)
Solar Reference Spectrum Chance and Kurucz, 2010
H2O Rothman et al., 2009; 280K
O3 cross sections Brion et al., 1998, 228K
NO2 cross sections Vandaele et al., 1998 220K
Liquid water Pope and Fry, 1997
C2H2O2 Volkamer et al., 2005, 296K
O2-O2 collisional complex BISA, 294K
Molecular Ring cross sections
Chance and Spurr, 1997
Liquid water ring effect Chance and Spurr, 1997
Sampling correction Computed on-line
Residual common mode spectrum
Computed on-line
H2O retrieval results
Exam
ple
retr
ieva
l res
ult Measured & fitted spectra
Fitting residual
Fitted water vapor + residual
Fitted liquid water + residual
Fitted NO2 + residual
Fitted O3 + residual
Open Ocean Coast
20050714
20070714
20110714
20130714
H2O retrieval results
H2O retrieval validation efforts
OMI Blue
MODIS Near IR
Com
paris
on w
ith A
ERO
NET
tim
e se
ries
H2O retrieval validation efforts
C2H2O2 retrieval set upFitting window 435 - 461 nm
Baseline polynomial 1st orderScaling polynomial 3rd order
Instrument slit function Hyper-parameterization of pre-flight measurements, Dirksen et al., 2006
Wavelength calibration Spectral shift (no squeeze)Solar Reference Spectrum Chance and Kurucz, 2010
C2H2O2 Volkamer et al., 2005, 296K
O3 cross sections Brion et al., 1998, 228K
NO2 cross sections Vandaele et al., 2003, 220K
Liquid water Pope and Fry, 1997O2-O2 collisional complex Thalman and Volkamer, 2013
Molecular Ring cross sections Chance and Spurr, 1997Sampling correction Computed on-line
Residual common mode spectrum Computed on-lineLiquid water pre-fit 385 – 470 nm (O3,NO2 and O2-O2 collision complex, 1st order
baseline, 5th order scaling)De-stripping Characterization of stripes over the Sahara and applied
elsewhere
C2H2O2 retrieval results
C2H2O2 OMI vs. GOME-2 (Lerot et al.)
New fields in the SAO L2 file
Albedo
GasProfile
ReferenceSectorCorrectedVerticalColumnScatteringWeights XtrackQualityflags
XtrackQualityflagsExpanded
Gonzalez Abad et al., Atmos. Meas. Tech. Discuss., 7, 1-31, 2014Wang at al., Atmos. Meas. Tech. Discuss., 7, 541-567, 2014
Miller at., in preparation
Thanks for your attention
We would like to thank NASA for funding
Water vapor retrieval• Fitting window 430 – 480 nm• H2O, O3, NO2, CHOCHO, O2-O2, Liquid H2O, ring, water
ring, 3rd order polynomials2005-07-14
Typical SCD uncertainty:(1.0-1.7)×1022 molec cm-2
Submitted to AMTD and accepted with corrections, H. Wang et. Al:Water Vapor Retrieval from OMI Visible Spectra
Post-processing reference sector correction
Row anomaly flags
SAO OMI H2O SCD sensitivityto retrieval window
Window Length (nm)
Retrieval Window (nm)
Median SCD
(molecule cm-2)
Median Uncertainty (molecule cm-2)
Median Relative Uncertainty
20 [435, 455] 1.47×1023 2.4×1022 0.19
30 [432, 462] 1.43×1023 2.0×1022 0.17
40 [438, 478] 1.35×1023 1.6×1022 0.15
50 (standard)
[430, 480] 1.32×1023 1.2×1022 0.11
65 [430, 495] 1.23×1023 1.5×1022 0.12
• SCD decreases by ~15% as window length increases from 20 nm to 65 nm.• The smallest uncertainty is achieved by the standard window of [430, 480]nm.
SAO OMI H2O sensitivity tointerfering molecules
Description Median SCD (molecule cm-2)
Median uncertainty (molecule cm-2)
Median RMS
Number of negatives
Standard 1.32×1023 1.2×1022 9.2e-4 1935Without O3 1.19×1023 1.2×1022 9.3e-4 7234Without O2-O2 1.18×1023 1.3×1022 9.9e-4 5076Without NO2 1.05×1023 1.2×1022 9.3e-4 15666Without liquid water 0.90×1023 1.1×1022 9.5e-4 50216Without C2H2O2 1.34×1023 1.2×1022 9.2e-4 1780
• The most important interfering molecules are liquid water, NO2 and O3.
C2H2O2 de-stripping
C2H2O2 de-stripping
H2CO/C2H2O2 ratio