1. Comparisons of TES v002 Nadir Ozone with GEOS-Chem by Ray Nassar & Jennifer Logan Thanks to: Lin Zhang, Inna Megretskaia, Bob Yantosca, Phillipe LeSager, Helen Worden & the TES Team GEOS-Chem Meeting, Harvard University, 2007 April 11-13

2. Tropospheric Emission Spectrometer (TES) Ray Nassar GEOS-Chem Meeting, Harvard University, 2007 April 11-13 High resolution Fourier transform spectrometer (FTS) on Aura satellite launched 2004 July 15, ~705 km sun-synch orbit, equator crossing ~13:45 Global Survey 16 orbits (~26 hrs) Nadir footprint: 5.3 km x 8.3 km Special observations: Step & stare, Transect, Stare, etc.

3. INTEX Ozonesonde Network Study (IONS), World Ozone and Ultraviolet Data Center (WOUDC) and Southern Hemisphere Additional Ozonesonde (SHADOZ) Archive ~1600 pairs with coincidence criteria of 300 km radius, ±9 hours October 2004 – October 2006

4. Applying the TES Averaging Kernel and Constraint Version 002 R2971_Seq0100_Scn003 Hohenpeissenberg (48N, 11W) 2005-07-18 ~4 Degrees of Freedom for Signal (DOFS) for O 3 when cloud free ~2 DOFS in troposphere Initial guess TES retrieval Sonde Sonde with TES op x sondeTESop = x prior + A TES [x sonde -x prior ]

5. TES - Sonde O 3 Differences in 6 Latitude Zones Ray Nassar GEOS-Chem Meeting, Harvard University, 2007 April 11-13 Removed flagged and cloudy profiles (Effective OD > 2.0, cloud top height above 750 hPa)

6. TES vs. Sonde O 3 Upper Troposphere (UT) and Lower Troposphere (LT) Average Correlations Correlation coefficients: 0.47 - 0.93  Good linearity Positive bias of 3-10 ppbv. High variability related to atmospheric variability so an upper limit for  of 7-16 ppbv low sensitivity

7. GEOS-Chem Simulation Version 7-04-10, GEOS-4 12 month spin-up, 18 month run from 2005-07 to 2006-12 2 x 2.5º resolution Daily and 2-hourly output Lightning settings for update by Lee Murray and Rynda Hudman (scaling with OTD-LIS) Global Fire Emission Database 2 (GFED2) emissions for 2005 & 2006 GEOS-Chem and TES Comparison Find GEOS-Chem pixel for TES measurement position and time (  t <1 hr) Apply TES averaging kernel and constraint to GEOS-Chem Monthly average TES data in 2 x 2.5º bins to match model run

8. GEOS-Chem & TES at 2 x 2.5º: October 2005 a) b) c)d)

9. GEOS-Chem & TES at 2 x 2.5º: January 2006 a) b) c)d)

10. 2006 – 2005 Difference Plots October November December

11. Conclusions TES V002 nadir ozone profiles typically have a high bias of 3-10 ppbv in all latitude zones relative to ozonesondes High variability related to atmospheric variability so an upper limit for  of 7-16 ppbv, relative variations in ozone measured by TES are meaningful GEOS-Chem underestimates tropical ozone relative to TES, especially in the southern tropical biomass burning season, but qualitatively good TES and GEOS-Chem show differences between 2006 and 2005 which likely relate to changes in biomass burning and/or lightning patterns due to the 2006 El Nino but requires further investigation

12. Future Work Screen TES ozone data using “emission layer” flag Apply vertical averaging over multiple layers to increase information content Re-run GEOS-Chem with different emissions, lightning parameters Determine if ozone is ‘conserved’ Investigate whether higher ozone correlates with CO or lightning

13. Extra slide: GEOS-Chem Run Settings