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Validation of OMI Total Ozone Column and Implications for Trend Studies

This study evaluates the accuracy of the Ozone Monitoring Instrument (OMI) in measuring total ozone column and discusses the implications for trend studies. It compares OMI data with ground-based measurements and identifies modifications made to the algorithms for better agreement. The results show a close match between OMI and reference data, making OMI a reliable tool for long-term ozone monitoring.

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Validation of OMI Total Ozone Column and Implications for Trend Studies

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  1. Validation of the Ozone Monitoring Instrument Total Ozone Column and Implications for Trend Studies M. Kroon1, R.D. McPeters2, J.P. Veefkind1, G. Labow2, D. Balis3, I. Petropavlovskikh4, P.K. Bhartia2, R. Shetter4 andP.F. Levelt1 1.Royal Netherlands Meteorological Institute, 2.NASA Goddard Space Flight Center, 3.Aristotle University of Thessaloniki, 4.NOAA/ESRL, 5.National Center for Atmospheric Research OMI Science Team Meeting Helsinki, 24 June 2008

  2. Total Ozone Column ECS2 > COL3 ECS2 COL3 September 2005 OMI TOMS V8.5 [DU] OMI TOMS V8.0 [DU]

  3. Total Ozone Column ECS2 > COL3 ECS2 COL3 September 2005 DOAS v1.0.5 [DU] DOAS v1.0.1 [DU]

  4. Changing Collection OMI-DOAS OMDOAO3 algorithm v1.0.5 release for OMI Collection 3 data. Collection 3 Level 1B has better dark current and stray light corrections yielding better fitting residuals and lower chi-squared. Treatment of high reflective surfaces (snow/ice) changed. Effective cloud fraction set to zero and surface albedo fitted (~OMTO3). Airmass factor tables updated. AMF tables primary cause for Solar Zenith Angle dependent bias. New air mass factor tables are based on improved radiative transfer calculations. Look-up table for cloud radiance fraction updated. New radiative transfer calculations include atmospheric sphericity. New static irradiance file produced by combining Solar irradiance data of collection 3 for year 2005.

  5. Changing Collection OMI-TOMS OMTO3 algorithm v8.5 release for OMI Collection 3 data. Ingesting daily OMCLDRR (Raman) cloud effective pressure and fraction “CloudFractionForO3” and “CloudPressureForO3”. Treatment of high reflective surfaces (snow/ice) changed. Cloud fraction set to zero at snow ice fraction >50%. Jump at Solar Zenith Angle 69º corrected by switching off change in climatological ozone profile used. Collection 3 Level 1B stray light corrections change yields OMTO3 to drop 6-7 DU on global scale. Under discussion!. OMSO2 algorithm improved yielding higher SO2 PBL values hence more SO2 polluted pixels correctly flagged hence less influence.

  6. Total Ozone Column ECS2 > COL3 Closer Match! Close Match

  7. Total Ozone Column ECS2 > COL3 0.90 < Regression < 1.03 0.91 < Correlation < 0.99 0.85 < Regression < 1.00 0.89 < Correlation < 0.98

  8. Total Ozone Column ECS2 > COL3 -7 < Difference < 1 8 < Deviation < 12 -8 < Difference < 3 10 < Deviation < 19

  9. Total Ozone Column ECS2 > COL3

  10. TO3C Difference ECS2 > COL3 ECS2 COL3 October 2005 OMI TOMS V8.5 - DOAS v1.0.5 [DU] OMI TOMS V8.0 - DOAS v1.0.1 [DU]

  11. TO3C Single Orbits ECS2

  12. TO3C Single Orbits COL3

  13. Influence of Sulphur Dioxide ECS2 20.2 N 139.0 E 152.4 E 12.4 N 20.2 N 139.0 E 152.4 E 12.4 N

  14. Influence of Sulphur Dioxide COL3 20.2 N 139.0 E 152.4 E 12.4 N 20.2 N 139.0 E 152.4 E 12.4 N

  15. Influence of Clouds ECS2

  16. Influence of Clouds COL3

  17. Ground Based vs OMTO3 ECS2 COL3 OMI AO 2925 - Validation of OMI total ozone using ground-based Brewer observations. Dr. Dimitris Balis, Aristotle University of Thessaloniki - Laboratory of Atmospheric Physics, Greece

  18. Ground Based vs OMTO3 ECS2 COL3 OMI AO 2925 - Validation of OMI total ozone using ground-based Brewer observations. Dr. Dimitris Balis, Aristotle University of Thessaloniki - Laboratory of Atmospheric Physics, Greece

  19. Ground Based vs OMDOAO3 ECS2 COL3 OMI AO 2925 - Validation of OMI total ozone using ground-based Brewer observations. Dr. Dimitris Balis, Aristotle University of Thessaloniki - Laboratory of Atmospheric Physics, Greece

  20. Ground Based vs OMDOAO3 ECS2 COL3 OMI AO 2925 - Validation of OMI total ozone using ground-based Brewer observations. Dr. Dimitris Balis, Aristotle University of Thessaloniki - Laboratory of Atmospheric Physics, Greece

  21. Ground Based Validation COL3 * No South Pole (lat > 75 S)

  22. NASA DC-8 no.817 NASA WB-57 no.926

  23. Polar-AVE 20050129 OMI Orbit 2890 CAFS TOMS vs CAFS ∆= -5.8 DU=-1.8% DOAS vs CAFS ∆=10 DU=2.9%

  24. Aura Validation Experiment OMI CAFS

  25. Solar Zenith Angle 200505 NH SH WG ECS2 NH SH WG COL3

  26. Required Accuracy Validation of ECS2 has led to many modifications made to the respective algorithms for COL3 reprocessing. For COL3 agreement is found within 1-2 % with reference data. Continuing the TOMS total ozone record (> November 1978) is thus achievable with OMI total ozone. Remaining difference between OMI-TOMS and OMI-DOAS total ozone estimates are significant in size compared to dynamic range covered by trends. Both algorithms are sensitive to calibration changes, but not up to the level that becomes significant for trends. 3% 100 DU

  27. Data Availability OMI DOAS Total Ozone Column : NASA DISC and NASA AVDC http://disc.gsfc.nasa.gov/Aura/OMI/index.shtml http://avdc.gsfc.nasa.gov/index.php?site=2045907950 OMI TOMS Total Ozone Column : NASA DISC and NASA AVDC http://disc.gsfc.nasa.gov/Aura/OMI/index.shtml http://avdc.gsfc.nasa.gov/index.php?site=2045907950 OMI Near Real Time Total Ozone Column : KNMI TEMIS http://www.temis.nl/protocols/O3total.html (NRT) http://www.temis.nl/protocols/O3global.html (Assim) OMI Very Fast Delivery Total Ozone Column : FMI OMIVFD http://omivfd.fmi.fi/cgi-bin/products.pl OMI Ozone Profiles : NASA AVDC (provisional) http://avdc.gsfc.nasa.gov/index.php?site=1980959093&id=39

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