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Cross Evaluation of OMI, TES, and GEOS-Chem Tropospheric Ozone

Cross Evaluation of OMI, TES, and GEOS-Chem Tropospheric Ozone. Xiong Liu 1 , Lin Zhang 2 , Kelly Chance 1 , John R. Worden 3 , Kevin W. Bowman 3 , Thomas P. Kurosu 1 , Daniel J. Jacob 2 1 Harvard-Smithsonian Center for Astrophysics 2 Harvard University 3 Jet Propulsion Laboratory

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Cross Evaluation of OMI, TES, and GEOS-Chem Tropospheric Ozone

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  1. Cross Evaluation of OMI, TES, and GEOS-Chem Tropospheric Ozone Xiong Liu1, Lin Zhang2, Kelly Chance1,John R. Worden3, Kevin W. Bowman3, Thomas P. Kurosu1, Daniel J. Jacob2 1Harvard-Smithsonian Center for Astrophysics 2 Harvard University 3 Jet Propulsion Laboratory 3rd GEOS-Chem Users’ Meeting 2007 Harvard University April 11, 2007

  2. Motivation TES retrievals and GEOS-Chem simulation Preliminary OMI ozone profile retrievals Comparison methodology OMI/TES/GEOS-Chem comparison Summary Outline

  3. Motivation • OMI/TES: both on EOS-AURA and measure tropospheric ozone • OMI:~10-12 km FWHM in the troposphere,13×24 km2, global coverage • TES:~6 km FWHM in the troposphere,5×8 km2 • Tropospheric ozone retrievals can be greatly improved with joint UV/IR retrievals [Worden et al., 2007]. • Are OMI/TES data consistent? • How well does GEOS-Chem simulation compare with OMI/TES ozone? Worden et al., 2007

  4. TES: V 2.0 Compares well with ozonesonde observations: generally biased higher by ~10% [Ray et al., 2007]. Compares well with DIAL obtained during the INTEX-B: Positive bias of 5-15% and a negative biases of up to 20% in the upper troposphere [Richard et al., 2007]. GEOS-Chem simulation: V7-04-09 with GEOS-4 Lightning NOx: 6 Tg/yr, rescaled with OTD/LIS climatology Increase Chinese NOx emission by ~70% (2006) TES Retrievals and GEOS-Chem Simulation

  5. OMI retrievals: O3 at 24 ~2.5 km layers with optimal estimation Fitting window: 270-310 nm (UV-1), 310-330 nm, 368-372 nm (UV-2) O3 climatology (month, lat, Z) [McPeters et al., 2007] as a priori (a) (b) Preliminary OMI Ozone Profile Retrievals May 8 2006 Overpass US Partial Column Ozone (DU) (a) Retrieval (b) A priori

  6. OMI calibration: wavelength and cross-track dependenterrors Derive soft correction (,, multiplicative) by simulating OMI radiances: McPeters (strat.) and Logan (1999) trop. O3 clima. Assumption: climatology represents ozone fields on global average Remove remaining systematic stripes (b) (d) (c) (a) artifacts due to aerosols and clouds (e) Preliminary OMI Ozone Profile Retrievals • May 8, 2006 • Original • Soft calib. • Soft calib. +destriping • A Priori • 600 mb • fc < 0.3

  7. OMI/TES retrievals: different retrieval grid and a priori Relatively coarser vertical resolution (vs. ozonesonde) TES: more tropospheric ozone information (two defined peaks) OMI: more stratospheric ozone information Examples of coincident clear-sky AKs (a) TES (67 levels) (b) OMI (24 layers) 15°N 40°N 60°N Comparison Methodology

  8. Use GEOS-Chem as an intermediate, also evaluate GEOS-Chem: Interpolate GEOS-Chem/TES to OMI grid (coarsest) Append GEOS-Chem with TES stratospheric ozone Compare GEOS-CEHM with TES (TES AKs + OMI a priori) Compare GEOS-CEHM with OMI (OMI AKs + OMI a priori) Compare OMI/TES directly, similar to Luo et al. [2007]: Interpolate TES to OMI grid and adjust TES with OMI a priori Apply OMI AKs to TES data Compare OMI/TES with ozonesonde observation later (not here) Present the comparison on May 08, 2006 (similar on other days) Remove poor retrievals (i.e., TES master flag, emission layer flag, OMI fitting residuals) and cloudy pixels (OMI fc > 0.3) 550 coincidences Comparison Methodology

  9. OMI/TES/GEOS-Chem TCO on May 8, 2006 Generally consistent spatial distribution despite systematic biases

  10. MB = -8% MB = -6% OMI TES MB = -7% MB = 4% GEOS CHEM TES OMI OMI/TES/GEOS-Chem TCO on May 8, 2006

  11. (a) (b) OMI/TES/GEOS-Chem Comparison Mainly systematic OMI/TES differences • Difference due to OMI/TES AKs can be up to 10-15% especially in UT • Large negative (10°N-20°N, high sun) and positive (40°S-25°S, low sun) biases may be caused by non-linearity of the OMI calibration.

  12. a b c d OMI/TES Comparison (b) Those biases are not caused by a priori (a, c, d) Mostly systematic differences

  13. The spatial distribution of OMI, TES, and GEOS-Chem tropospheric ozone is similar on the global scale. TES shows a systematic positive bias of ~10% relative to GEOS-Chem. OMI shows a negative bias of ~15% relative to TES except for 10°N-20°N (~ -30%) and 45°S-25°S (~20%). The large negative bias at high sun and positive bias at low sun may be related to the non-linearity calibration of OMI. OMI/TES differences cannot be explained by a priori and different averaging kernels, and are mainly systematic. Acknowledgements OMI and TES science team, GEOS-Chem community NASA and Smithsonian Institution Summary

  14. OMI/TES/GEOS-Chem Ozone (600 mb)(North Pacific during INTEX-B, May 05-09, 2006) 05/05 05/06 05/07 05/08 05/09

  15. OMI TCO (North Pacific on May 05-10, 2006) OMI tropospheric column ozone fc < 0.3 Gridded to 2.5°×2°

  16. OMI/TES/GEOS-Chem Ozone (600 mb) on May 04-12, 06 05/04 05/06 05/08 05/10 05/12 Persistent high O3 over Northern India from OMI, not clear from TES, not shown in GEOS-Chem. Maybe be due to OMI retrieval artifacts: (a) absorbing aerosols (b) incorrect terrain height

  17. How does the Appending of Different Stratospheric Ozone to GEOS-Chem Affect the Comparison? Append GEOS-Chem with OMI a Priori stratospheric ozone Append GEOS-Chem with TES stratospheric ozone

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