SAO OMI formaldehyde, water vapor and glyoxal retrievals Gonzalo Gonzalez Abad Helen Wang Christopher Miller Kelly Chance Xiong Liu Thomas Kurosu OMI Science Team Meeting 12 th March 2014

Summary Formaldehyde – Updates to spectroscopy – Slant column fitting – Air mass factor calculation – Reference Sector Correction – Old vs. new SAO H 2 CO Water vapor – Retrieval set up – Results – Early validation Glyoxal – Retrieval set up – Results – OMI vs GOME-2 New L2 files fields and information

H 2 CO spectroscopy updates H 2 CO cross sections High resolution solar spectrum

H 2 CO spectroscopy updates: O 2 -O 2 collision complex cross sections

H 2 CO Slant Column Fitting OperationalNew version

H 2 CO Slant Column Fitting: Orbit #43214

Shared Air Mass Factor Calculation for H 2 CO, C 2 H 2 O 2 and H 2 O 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 nm for H 2 CO 448 nm for C 2 H 2 O nm for H 2 O

H 2 CO AMF calculation: Orbit st February 2006

H 2 CO AMF calculation: an e xample of scattering weights

H 2 CO reference sector correction

Old vs. new SOA H 2 CO product: Orbit #43214

H 2 CO time series and L3 comparison: old vs. new SAO retrievals

H 2 O retrieval set up

H 2 O retrieval results Example retrieval result Measured & fitted spectra Fitting residual Fitted water vapor + residual Fitted liquid water + residual Fitted NO 2 + residual Fitted O 3 + residual Open OceanCoast

H 2 O retrieval results

H 2 O retrieval validation efforts OMI Blue MODIS Near IR

Comparison with AERONET time series H 2 O retrieval validation efforts

C 2 H 2 O 2 retrieval set up

C 2 H 2 O 2 retrieval results

C 2 H 2 O 2 OMI vs. GOME-2 (Lerot et al.)

New fields in the SAO L2 file Albedo GasProfile ReferenceSectorCorrectedVerticalColumn ScatteringWeights XtrackQualityflags XtrackQualityflagsExpanded Gonzalez Abad et al., Atmos. Meas. Tech. Discuss., 7, 1-31, 2014 Wang at al., Atmos. Meas. Tech. Discuss., 7, , 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 H 2 O, O 3, NO 2, CHOCHO, O 2 -O 2, Liquid H 2 O, ring, water ring, 3 rd order polynomials Typical SCD uncertainty: ( )×10 22 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 H 2 O SCD sensitivity to 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× × [432, 462]1.43× × [438, 478]1.35× × (standard) [430, 480]1.32× × [430, 495]1.23× × 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 H 2 O sensitivity to interfering molecules DescriptionMedian SCD (molecule cm -2 ) Median uncertainty (molecule cm -2 ) Median RMS Number of negatives Standard1.32× × e Without O × × e Without O 2 -O × × e Without NO × × e Without liquid water0.90× × e Without C 2 H 2 O × × e The most important interfering molecules are liquid water, NO 2 and O 3.

C 2 H 2 O 2 de-stripping

H 2 CO/C 2 H 2 O 2 ratio