1. 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

2. 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

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

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

5. H 2 CO Slant Column Fitting OperationalNew version

6. H 2 CO Slant Column Fitting: Orbit #43214

7. 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 2007 340 nm for H 2 CO 448 nm for C 2 H 2 O 2 455 nm for H 2 O

8. H 2 CO AMF calculation: Orbit 8537 21 st February 2006

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

10. H 2 CO reference sector correction

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

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

13. H 2 O retrieval set up

14. 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

15. 20050714 20070714 20110714 20130714 H 2 O retrieval results

16. H 2 O retrieval validation efforts OMI Blue MODIS Near IR

17. Comparison with AERONET time series H 2 O retrieval validation efforts

18. C 2 H 2 O 2 retrieval set up

19. C 2 H 2 O 2 retrieval results

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

21. 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, 541-567, 2014 Miller at., in preparation

22. Thanks for your attention We would like to thank NASA for funding

23. 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 2005-07-14 Typical SCD uncertainty: (1.0-1.7)×10 22 molec cm -2 Submitted to AMTD and accepted with corrections, H. Wang et. Al: Water Vapor Retrieval from OMI Visible Spectra

24. Post-processing reference sector correction

25. Row anomaly flags

26. 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]1.47×10 23 2.4×10 22 0.19 30[432, 462]1.43×10 23 2.0×10 22 0.17 40[438, 478]1.35×10 23 1.6×10 22 0.15 50 (standard) [430, 480]1.32×10 23 1.2×10 22 0.11 65[430, 495]1.23×10 23 1.5×10 22 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.

27. SAO OMI H 2 O sensitivity to interfering molecules DescriptionMedian SCD (molecule cm -2 ) Median uncertainty (molecule cm -2 ) Median RMS Number of negatives Standard1.32×10 23 1.2×10 22 9.2e-41935 Without O 3 1.19×10 23 1.2×10 22 9.3e-47234 Without O 2 -O 2 1.18×10 23 1.3×10 22 9.9e-45076 Without NO 2 1.05×10 23 1.2×10 22 9.3e-415666 Without liquid water0.90×10 23 1.1×10 22 9.5e-450216 Without C 2 H 2 O 2 1.34×10 23 1.2×10 22 9.2e-41780 The most important interfering molecules are liquid water, NO 2 and O 3.

28. C 2 H 2 O 2 de-stripping

30. H 2 CO/C 2 H 2 O 2 ratio