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N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI

Evaluation of model simulations with satellite observed NO 2 columns and surface observations & Some new results from OMI. N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI M. van Roozendael, I. De Smedt, BIRA-IASB.

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N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI

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  1. Evaluation of model simulations with satellite observed NO2 columns and surface observations&Some new results from OMI N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI M. van Roozendael, I. De Smedt, BIRA-IASB EUMETNET-EEA, Copenhagen, 7-8 April 2005

  2. Combining retrieval, modelling and assimilation to obtain NO2 tropospheric columns from SCIAMACHY/GOME Careful treatment needed for: • Clouds • Surface albedo • Profile shape (TM)

  3. Validation of (stratospheric) NO2 columns with ground-based observations Good agreement in remote areas Deviations in industrialised (as expected)

  4. Combined retrieval - modelling - assimilation approach to GOME NO2 30 x 60 km2

  5. Chimère model Developed in France R. Vautard, H. Schmidt, L. Menut, M. Beekman, N. Blond, ... ) Operational air-quality forecasts: www.prevair.org Model ingredients: • MELCHIOR chemistry (82 species, 333 reactions) • EMEP emissions • ECMWF meteorological analyses • 15 vertical layers, surface - 200 hPa • Boundary conditions from MOZART monthly-mean climatology

  6. Emissions (EMEP)

  7. Motivation for comparison of Chimere with both ground-based and satellite obs Motivation • Lack of NO2 profile observations for validating SCIAMACHY. Intermediate step: compare to a model Approach • Space-time co-location of Chimère output with individual “cloud-free” SCIA pixels • Use averaging kernels from SCIAMACHY: Modelled column = SCIAMACHY kernel vector • model profile • 1 year of SCIAMACHY data - 2003 Advantages • Comparison model-SCIAMACHY under exactly same conditions • Comparison independent of profile shape assumptions in retrieval

  8. Comparison of Chimère to surface observations -- surface obs -- Chimère Netherlands rural stations: Bias 0.1 ppb, RMS 7.2 ppb, Correlation 0.66

  9. SCIAMACHY vs. Chimère: yearly mean Yearly-mean bias = 0.2 1015 molec. cm-2, RMS 2.9, correlation 0.73 Cloud-free pixels only

  10. SCIAMACHY vs. Chimère: 27 Feb 2004

  11. SCIAMACHY vs. Chimère: 28 Mar 2004

  12. Conclusions of evaluation SCIAMACHY-Chimère- surface obs • Yearly mean: - very small bias SCIAMACHY - Chimère and Chimère - surface - Correlation coefficients ~0.7 • NO2 plumes similar • Differences in details: - Seasonality (Chimère higher in winter) - Individual days - Detailed distribution

  13. Planned KNMI web service: Surface - Chimère - satellite

  14. OMI TES MLS HIRDLS New results from the Ozone Monitoring Instrument (OMI) Launched: 15 July 2004 on EOS-AURA

  15. OMI results: NO2 Courtesy: Pepijn Veefkind cloud cloud 13 x 24 km2 with daily global coverage

  16. Galeras and Tungurahua volcanoes La Oroya Cu-smelter Ilo Cu-smelter OMI results: SO2 (Carn et al.) Jan 2005 G&T: 5300 td-1 Or: 500 td-1 Ilo: 1250 td-1

  17. OMI results: formaldehyde

  18. Internet addresses Satellite products www.gse-promote.org www.temis.nl OMI www.knmi.nl/omi eos-aura.gsfc.nasa.gov

  19. Spare slides

  20. NO2 column retrieval approach Air-mass factor calculation • Temperature correction (NO2 cross section) • TM4 global chemistry transport model (profiles) • Assimilation of slant columns -> stratospheric "background" • Fresco cloud fraction and cloud top pressure retrieval • TOMS / GOME combined albedo map (Herman, Koelemeijer) • DAK RTM height-dependent AMF lookup table • Tropospheric AMF based on TM profile shape, clouds Output • Detailed error estimates • Averaging kernels

  21. SCIAMACHY vs. Chimère: 16 April 2004

  22. SCIAMACHY vs. Chimère: 16 Sept 2004

  23. Satellite instruments providing NO2 columns • GOME (April 1995, ERS-2, 40 x 320 km2) • SCIAMACHY (February 2002, ENVISAT, 30 x 60 km2) • OMI & TES (15 July 2004, EOS-AURA, 13 x 24 km2)

  24. 2-dimensional CCD swath wavelength ~ 580 pixels ~ 780 pixels flight direction » 7 km/sec viewing angle ± 57 deg 12 km/24 km (binned & co-added) 13 km 2600km (2 sec flight)) OMI measurement principle

  25. OMI properties • UV and VIS backscatter spectrophotometer (270 - 500 nm) • Wide swath (2600 km) telescope yields daily global maps • Resolution of 13 x 24 km2 is best ever for air quality applications • Products: • Ozone: total and tropospheric columns, profiles • NO2 columns • HCHO columns • SO2 columns • & Clouds (coverage, top pressure), Aerosols, BrO, OClO, Surface UV Irradiance

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