1. Tropospheric NO2 Ronald van der A, Michel Van Roozendael, Isabelle De Smedt, Ruud Dirksen, Folkert Boersma KNMI and BIRA-IASB Barcelona, June 2009

2. Monitoring by satellite UV-VIS retrievals NO2 SO2 HCHO O3 Infrared retrievals CO CH4 ATSR retrievals Aerosols

4. Trend in tropospheric NO 2 (1996-2006) Tehran, Delhi Calcutta van der A et al., JGR, 2008

5. Continuation with OMI (2004 - now)

6. Overpass files

7. Summary Tropospheric NO2  GOME/SCIAMACHY/OMI/GOME-2 NO2 data available for 1996-today.  Data is used for trend analysis, shipping routes, source identification, diurnal cycle.  Monitoring of China with SCIAMACHY/GOME-2 (overpass at 10.00/9.30 AM ) and OMI (overpass at 13.30 PM)  Overpass files for GOME-2 and OMI pixels within 100 km from station.

8. GOME tropospheric O3 columns R. van der A, J. de Laat, J. van Peet, O. Tuinder (KNMI)

9. Directly measuring tropospheric O3 from space: GOME OPERA algorithm (Ozone ProfilE Retrieval Algorithm) Non-linear Optimal Estimation [Rodgers], iterative, use of a-priori Limited height information [Degrees of Freedom for Signal] About 5 independent pieces of vertical information  Smoothing of actual profile !!  about 1 piece of tropospheric information [cf. Liu et al., JGR, 2005] Courtesy J. Landgraf, SRON

13. New approach: data assimilation Determine SOC by assimilating OPERA O3 profiles using CTM (TM5) Then: TTOC = TOC - SOC Advantages: - No gaps in SOC  internal consistency - Better solution for “smoothing error” - Internally consistent tropopause  Best available estimate of SOC

14. Assimilation of GOME-2 ozone UV/VIS ozone profile assimilation with TM5 –single O3 tracer based on Cariolle linearized O3 –chemistry (Cariolle and Duque [1986; JGR], improved version in 2007 [Cariolle and Teyssedre; ACP]) –ECMWF meteo data –assimilation of O3 profile using Kalman filter [Eskes,Segers].

15. Tropospheric Ozone data GOME tropospheric columns:  Data set complete  Low resolution => low quality  Small improvements possible  GOME-2 tropospheric columns:  Data set not available yet  High quality  Long processing time  GOME-2 tropospheric profiles:  Data set is available  Data is difficult to interpret: averaging kernel and a-priori profile needed

16. Summary tropospheric ozone Ozone profile datasets available Processing is time consuming Useful feedback from validation done by MariLiza Data assimilation of profiles is under development