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Assimilation of Atmospheric Composition at ECMWF

Overview of ozone assimilation and monitoring, assimilation of other atmospheric composition products, operational user requirements, and future plans at ECMWF.

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Assimilation of Atmospheric Composition at ECMWF

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  1. Assimilation of atmospheric composition at ECMWFRossana DraganiECMWFwith acknowledgements to Antje Dethof, Richard Engelen, Angela Benedetti, and Adrian Simmons TROPOMI workshop, KNMI, 5-6 March 2008

  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, CH4, NO2) • Operational user requirements • Concluding remarks TROPOMI workshop, KNMI, 5-6 March 2008

  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. TROPOMI workshop, KNMI, 5-6 March 2008

  4. Ozone data assimilation: TOSOMI TCO • 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. Without SCIA With SCIA TOMS TROPOMI workshop, KNMI, 5-6 March 2008

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

  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 O3 thinned on 1o by 1o 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 TROPOMI workshop, KNMI, 5-6 March 2008

  7. OMI TCO assimilation:comparison with MLS and N18 SBUV/2 CTRL OMIT 2-3% reduction 5DU reduction • N18 SBUV/2 (v6) • 1 Jul – 31 Aug 2006 • Surface – 15 hPa • MLS O3 profiles (v02.22) • 1 Jul – 31 Aug 2006 • Almost 175000 profiles Slide 7 TROPOMI workshop, KNMI, 5-6 March 2008 TROPOMI workshop, KNMI, 5-6 March 2008

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

  9. Potential use of TROPOMI deliverables: • TROPOMI will provide measurements of O3, CH4, HCHO, NO2, CO, SO2, and aerosols. • ECMWF coordinates the EC-funded project GEMS (Global and regionalEarth-systemMonitoring 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-...). TROPOMI workshop, KNMI, 5-6 March 2008

  10. Assim Control Mozaic Assimilation of MOPITT TCCO: Aug 2003 Assimilation minus control Unit: 1018 molec/cm2 TROPOMI workshop, KNMI, 5-6 March 2008

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

  12. Assim Mozaic Tropospheric O3 profiles (Sep 2003) TROPOMI workshop, KNMI, 5-6 March 2008 MOZAIC data provided by Carlos Ordonez

  13. GOME monthly mean total column HCHO (BIRA retrieval) http://www.gse-promote.org/ Formaldehyde July 1999 GEMS total column HCHO (1-15 Jul 1999) Unit: 1015 molec/cm2 TROPOMI workshop, KNMI, 5-6 March 2008

  14. Global mean SCIA NO2 (Oct-Nov 2003) Passive monitoring of KNMI NO2 data retrieved from SCIAMACHY. Unit: 1015 molec/cm2 Slide 14 TROPOMI workshop, KNMI, 5-6 March 2008 TROPOMI workshop, KNMI, 5-6 March 2008

  15. Assimilation of SCIAMACHY CH4observations Gridded used observations (Sep-Oct) • SCIA retrievals have been used in a 1-year CH4 reanalysis. • Most observations over ocean are not used and therefore the largest impact is over land. Gridded first-guess departures (Sep-Oct) TROPOMI workshop, KNMI, 5-6 March 2008

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

  17. AMSU WITHOUT METOP WITH METOP 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 TROPOMI workshop, KNMI, 5-6 March 2008

  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. TROPOMI workshop, KNMI, 5-6 March 2008

  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 (O3, CH4, HCHO, CO, NO2, SO2) • 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 TROPOMI workshop, KNMI, 5-6 March 2008

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