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Daily Tropospheric Ozone Residual from OMI-MLS

Daily Tropospheric Ozone Residual from OMI-MLS. M. Schoeberl, J. Ziemke, P. K. Bhartia, A. Douglass, B. Duncan & GMI Team NASA/GSFC L. Froidevaux, N. Livesey, J. Waters JPL P. Levelt KNMI, Netherlands. Tropospheric Ozone Residual (TOR). Subtraction of OMI data from MLS

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Daily Tropospheric Ozone Residual from OMI-MLS

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  1. Daily Tropospheric Ozone Residual from OMI-MLS M. Schoeberl, J. Ziemke, P. K. Bhartia, A. Douglass, B. Duncan & GMI Team NASA/GSFC L. Froidevaux, N. Livesey, J. Waters JPL P. Levelt KNMI, Netherlands

  2. Tropospheric Ozone Residual (TOR) Subtraction of OMI data from MLS Problem: MLS stratospheric data has ~100 times lower spatial resolution than OMI (~25º vs ~0.25º). MLS Stratospheric O3 Column Map made from MLS measurement points shown

  3. High Resolution Stratospheric Ozone Column To increase the effective resolution of the MLS data, forward trajectories mapped from the previous 6 days on to the orbit track. Theoretical Improvement: 6 days of trajectory mapping gives ~ 2-3º horizontal resolution.

  4. Look at a specific example 6 day average Air pollution transport? 0 ppbv 80 Ziemke et al. 2006 - asynoptic low res. stratosphere

  5. Column Ozone June 28, 2005

  6. Tropopause HeightJune 28, 2005 20 km 5 km

  7. 6 day average Ziemke et al. 2006 80 0 ppbv Tropospheric Equivalent Mixing Ratio The high ozone feature off the east coast appears to be a fold - white contours show the tropopause gradient - not pollution. However, the magnitude of the fold tropospheric ozone event is very high….

  8. Improved Time Synchronization In the previous example the all data is assumed to asynoptic - measurement times are ignored. This can create problems with rapid moving events like folds. Synoptic TOR • Use OMI L2G with measurement time stamp • Forward trajectories are grouped in time for target day (1/10th day resolution) • Tropopause is time interpolated from 6 hour DAS fields ----------- • Product has same zonal mean as asynoptic TOR • Fold TOR anomalies are greatly reduced

  9. Time Synchronized Product Tropospheric Column Not Time Synchronized Time Synchronized

  10. More Results • All OMI - MLS data processed from Sept-04 to Aug-06 • Bad or missing MLS data profiles flagged • Data below p > 215 hPa not used

  11. Column Ozone vs Average Column Mixing Ratio Sept-Aug‘05 Trop. Column Ozone and Average Mixing Ratio ppbv DU (HTOR) The tropospheric equivalent mixing ratio tends to reduce the topographic effects.

  12. Seasonal TOR Mixing Ratio March - May Dec. - Feb. Sept. - Nov. June - Aug.

  13. Comparison to GMI Combo Jan 6, 2005

  14. Seasonal Variations (2005) Extra-tropical (tropical) region is defined as region where the tropopause is below (above) 12 km. The mass is normalized to the annual averaged area occupied by the respective regions.

  15. Zonal Mean Variations 2005 J J

  16. Summary • Forward Trajectory transport of MLS data is used to create a high horizontal resolution stratospheric ozone column which is then used to produce an improved tropospheric ozone residual (TOR). • Fold events appear to dominate TOR day-to-day extra-tropics, but using better time synchronization, fold event amplitudes are greatly reduced. • Results show strong pollution regions off the coasts of Africa in Sept.- Nov.; China and Eastern US in the March-Aug. The later two are enhanced by fold events that also occur in that corridor. • Comparisons of total tropospheric ozone amount to GMI Combo model show good agreement • Differences in extra-tropics probably due to more vigorous circulation in GMI • Differences in tropics due to different emissions and convection

  17. The End

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