1. Slide 1 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 1 Assimilation of atmospheric composition at ECMWF Rossana Dragani ECMWF with acknowledgements to Antje Dethof, Richard Engelen, Angela Benedetti, and Adrian Simmons

2. Slide 2 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 2 Overview: Ozone assimilation and monitoring from TROPOMI predecessors (SCIAMACHY, GOME, OMI, GOME-2) Monitoring and assimilation of other-than-ozone products at ECMWF (CO, HCHO, CH 4, NO 2 ) Operational user requirements Concluding remarks

3. Slide 3 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 3 The ECMWF operational suite: Global spectral model T799 (~ 25 km) and L91 from the surface up to 0.01 hPa (from 1 Feb 2006, CY30R1). The data assimilation is performed using the 4D-Var scheme, with: -two main 6-hour 4D-Var early-delivery analysis and forecast cycles for 00 and 12 UTC; -two main 12-hour 4D-Var delayed cut-off analysis and forecast cycles for 00 and 12 UTC. More than 5,000,000 observations from different sources and platforms (synops, ships, aircrafts, and satellites) are actively assimilated every 12 hours. KNMI SCIA (TOSOMI) TCO, N16, N17, and N18 SBUV/2 ozone partial columns are actively assimilated in o-suite. OMI TCO will be assimilated in the next operational suite.

4. Slide 4 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 4 Ozone data assimilation: TOSOMI TCO Without SCIA With SCIA TOMS Passively monitored in IFS from Mar to Sep 2004. Actively assimilated since 28 Sep 2004 (CY28R4). The assimilation of TOSOMI TCO improved the ozone analyses, especially in the tropics and SH. Comparisons with sondes also showed improvements in the polar regions.

5. Slide 5 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 5 ERA-Interim TOMS Assimilation of GOME profile data in ERA-Interim leads to much improved vertical distribution. Ozone data assimilation: RAL GOME ozone profiles in reanalysis ERA-40

6. Slide 6 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 6 Assimilation of OMI (DOAS) TCO: Introduced in o-suite for passive monitoring on 6 Nov 2007 (CY32R3). The OMI assimilation trial made use of the current operational suite (CY32R3) at T255 (~ 100 km), and L60 (surface up to 0.1 hPa), using the 4D-Var scheme with two main 12-hour analysis and first-guess forecast cycles for 00 and 12 Z. Period: 1 July – 31 August 2006 Ozone data actively assimilated: -Control exp ( CTRL ):  KNMI SCIAMACHY TCO O 3 thinned on 1 o by 1 o grid. No ozone bias correction was used. OMI contribution is mainly localized in the region between 10-80hPa. -Perturbation exp ( OMIT ):  KNMI SCIAMACHY TCO  OMI (DOAS) TCO Slide 6 TROPOMI workshop, KNMI, 5-6 March 2008

7. Slide 7 OMIT CTRL TROPOMI workshop, KNMI, 5-6 March 2008 Slide 7 OMI TCO assimilation: comparison with MLS and N18 SBUV/2 MLS O 3 profiles (v02.22) 1 Jul – 31 Aug 2006 Almost 175000 profiles N18 SBUV/2 (v6) 1 Jul – 31 Aug 2006 Surface – 15 hPa 2-3% reduction 5DU reduction Slide 7 TROPOMI workshop, KNMI, 5-6 March 2008

8. Slide 8 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 8 Preliminary comparison between GOME2 and ECMWF TCO analyses (passive) ~ -0.8DU

9. Slide 9 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 9 Potential use of TROPOMI deliverables: TROPOMI will provide measurements of O 3, CH 4, HCHO, NO 2, CO, SO 2, and aerosols. ECMWF coordinates the EC-funded project GEMS (Global and regional Earth-system Monitoring using Satellite and in-situ data) [FP6, 2005-2009]. GEMS is an articulate project with 32 partners aiming at developing: -global modelling and data assimilation for greenhouse gases, reactive gases and aerosols; -a production system, including surface-flux estimation; -regional modelling for analysing and forecasting air quality for Europe. Envisaged evolution: -A pilot pre-operational GMES Atmospheric Service (2009-2011) MACC -Operational core GMES Atmospheric Service (2012-...).

10. Slide 10 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 10 Assimilation of MOPITT TCCO: Aug 2003 Assimilation minus control Unit: 10 18 molec/cm 2 Assim Control Mozaic

11. Slide 11 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 11 Time series of zonal Mean GEMS TCO

12. Slide 12 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 12 Tropospheric O 3 profiles (Sep 2003) Assim Mozaic MOZAIC data provided by Carlos Ordonez

13. Slide 13 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 13 Formaldehyde July 1999 GEMS total column HCHO (1-15 Jul 1999) Unit: 10 15 molec/cm 2 GOME monthly mean total column HCHO (BIRA retrieval) http://www.gse-promote.org/

14. Slide 14 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 14 Global mean SCIA NO 2 (Oct-Nov 2003) Unit: 10 15 molec/cm 2 Passive monitoring of KNMI NO 2 data retrieved from SCIAMACHY. Slide 14 TROPOMI workshop, KNMI, 5-6 March 2008

15. Slide 15 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 15 Assimilation of SCIAMACHY CH 4 observations Gridded used observations (Sep-Oct) Gridded first-guess departures (Sep-Oct) SCIA retrievals have been used in a 1-year CH 4 reanalysis. Most observations over ocean are not used and therefore the largest impact is over land.

16. Slide 16 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 16 Assimilation of MODIS AOD data MODIS observations Assimilation of MODIS aerosol optical depth for August 2003 Experiments are averaged from 1 to 15 August 2003 Control Model includes: Sea salt Desert dust Black carbon Organic matter MISR observations Slide 16 TROPOMI workshop, KNMI, 5-6 March 2008

17. Slide 17 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 17 Operational user requirements: Synergy between instruments with different characteristics (geometry and spectral range) is desirable as they can provide complementary information (Post-EPS Atmospheric Chemistry Data User Requirements by Kelder et al, 2006). Optimal data coverage: -Revisit time (for e.g. air quality) vs. “uniform” coverage requirements of global data assimilation systems -Data coverage vs. data redundancy WITHOUT METOPWITH METOP AMSU

18. Slide 18 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 18 Operational user requirements: Readiness: -Easy and early access to the data after launch essential to exploit the full (sometimes short) lifetime of an instrument. -NWP assumes privileged role for providing feedback to space agencies. Timeliness: -Customers want forecasts early, therefore NWP requires data early. Error characterization: -Errors define the weight given to the observations in the assimilation system.

19. Slide 19 TROPOMI workshop, KNMI, 5-6 March 2008 Slide 19 Summary ECMWF has successfully been assimilating ozone data from TROPOMI predecessors SCIAMACHY, GOME-1, and OMI. Given the data quality, GOME-2 TCO will soon be actively assimilated as well. The GEMS system is ready to use a number of different products which will be delivered by TROPOMI (O 3, CH 4, HCHO, CO, NO 2, SO 2 ) Data user requirements: -A fast, easy, and timely access to the data is essential for the exploitation of the whole missions, and to provide timely feedbacks to the data providers. -Whenever possible, synergistic use of different sensors on the same platform is desirable -Error characterization