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Published byLindsay Jacobs Modified over 9 years ago
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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 EUMETNET-EEA, Copenhagen, 7-8 April 2005
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Combining retrieval, modelling and assimilation to obtain NO 2 tropospheric columns from SCIAMACHY/GOME Careful treatment needed for: Clouds Surface albedo Profile shape (TM)
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Validation of (stratospheric) NO 2 columns with ground-based observations Good agreement in remote areas Deviations in industrialised (as expected)
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Combined retrieval - modelling - assimilation approach to GOME NO 2 30 x 60 km 2
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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
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Emissions (EMEP)
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Motivation Lack of NO 2 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 Motivation for comparison of Chimere with both ground-based and satellite obs
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Comparison of Chimère to surface observations Netherlands rural stations: Bias 0.1 ppb, RMS 7.2 ppb, Correlation 0.66 -- surface obs -- Chimère
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SCIAMACHY vs. Chimère: yearly mean Yearly-mean bias = 0.2 10 15 molec. cm -2, RMS 2.9, correlation 0.73 Cloud-free pixels only
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SCIAMACHY vs. Chimère: 27 Feb 2004
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SCIAMACHY vs. Chimère: 28 Mar 2004
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Conclusions of evaluation SCIAMACHY-Chimère- surface obs Yearly mean: - very small bias SCIAMACHY - Chimère and Chimère - surface - Correlation coefficients ~0.7 NO 2 plumes similar Differences in details: - Seasonality (Chimère higher in winter) - Individual days - Detailed distribution
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Planned KNMI web service: Surface - Chimère - satellite
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New results from the Ozone Monitoring Instrument (OMI) OMI MLS HIRDLS TES Launched: 15 July 2004 on EOS-AURA
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OMI results: NO 2 Courtesy: Pepijn Veefkind 13 x 24 km 2 with daily global coverage cloud
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OMI results: SO2 (Carn et al.) Galeras and Tungurahua volcanoes La Oroya Cu-smelter Ilo Cu-smelter Jan 2005 G&T: 5300 td -1 Or: 500 td -1 Ilo: 1250 td -1
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OMI results: formaldehyde
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Internet addresses Satellite products www.gse-promote.org www.temis.nl OMI www.knmi.nl/omi eos-aura.gsfc.nasa.gov
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Spare slides
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NO 2 column retrieval approach Air-mass factor calculation Temperature correction (NO 2 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
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SCIAMACHY vs. Chimère: 16 April 2004
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SCIAMACHY vs. Chimère: 16 Sept 2004
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Satellite instruments providing NO 2 columns GOME (April 1995, ERS-2, 40 x 320 km 2 ) SCIAMACHY (February 2002, ENVISAT, 30 x 60 km 2 ) OMI & TES (15 July 2004, EOS-AURA, 13 x 24 km 2 )
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OMI measurement principle 13 km (2 sec flight) ) 2600 km 12 km/24 km (binned & co-added) flight direction » 7 km/sec viewing angle ± 57 deg 2-dimensional CCD wavelength ~ 780 pixels swath ~ 580 pixels
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OMI properties UV and VIS backscatter spectrophotometer (270 - 500 nm) Wide swath (2600 km) telescope yields daily global maps Resolution of 13 x 24 km 2 is best ever for air quality applications Products: Ozone: total and tropospheric columns, profiles NO 2 columns HCHO columns SO 2 columns & Clouds (coverage, top pressure), Aerosols, BrO, OClO, Surface UV Irradiance
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