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Randall Martin

Using Satellite Data to Infer Surface Emissions and Boundary Layer Concentrations of NO x (and SO 2 ). Randall Martin. With contributions from: Xiong Liu, Chris Sioris, Kelly Chance (Harvard-Smithsonian Center for Astrophysics) Rob Pinder, Robin Dennis (EPA/NOAA).

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Randall Martin

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  1. Using Satellite Data to Infer Surface Emissionsand Boundary Layer Concentrations of NOx (and SO2) Randall Martin With contributions from: Xiong Liu, Chris Sioris, Kelly Chance (Harvard-Smithsonian Center for Astrophysics) Rob Pinder, Robin Dennis (EPA/NOAA)

  2. Satellite Instruments With the Capability of Remote Sensing of Tropospheric NO2 and SO2 Columns • Nadir-viewing solar backscatter instruments including visible(NO2)and ultraviolet (SO2) wavelengths • GOME/ERS-2 1995-2002 • Spatial resolution 320x40 km2 • Global coverage in 3 days • SCIAMACHY/Envisat 2002-present • Spatial resolution 60x30 km2 • Global coverage in 6 days • OMI/Aura 2004-present • Spatial resolution 24x13 km2 • Daily global coverage

  3. Spectral Fit of NO2 Solar Io Distinct NO2 Spectrum Ozone Backscattered intensity IB NO2 Scattering by Earth surface and by atmosphere Albedo A O2-O2 Nonlinear least-squares fitting Martin et al., 2002, 2006

  4. Total NO2 Slant Columns Observed from SCIAMACHY Dominant stratospheric background (where NO2 is produced from N2O oxidation)Also see tropospheric hot spots (fossil fuel and biomass burning) May-October 2004 Retrieval Uncertainty Spectral fit 5-10x1014 molec cm-2 Stratospheric removal 2-10x1014 molec cm-2

  5. Perform an Air Mass Factor (AMF) Calculation to Account for Viewing Geometry and Scattering Cloud Radiance Fraction IB,c / (IB,o + IB,c) IB,c IB,o • GOMECAT (Kurosu) & FRESCO Clouds Fields [Koelemeijer et al., 2002] • Surface Reflectivity [Koelemeijer et al., 2003] • LIDORT Radiative Transfer Model [Spurr et al., 2002] • GEOS-CHEM NO2 & aerosol profiles Io q Rc Ro Pc AMF Uncertainty 40% dt Rs Palmer et al., 2001; Martin et al., 2002, 2003

  6. Cloud-filtered Tropospheric NO2 Columns Retrieved from SCIAMACHY May 2004 – Apr 2005 Mean Uncertainty ±(5x1014 + 30%) Martin et al., 2006

  7. Tropospheric NO2 Columns More Sensitive to Lower Tropospheric NOx Upper Troposphere hv NO Ozone (O3) NO2 O3,RO2 NOx lifetime ~ week HNO3 NO/NO2  with altitude Boundary Layer hv NO2 Ozone (O3) NO O3,RO2 NOx lifetime < day HNO3 Nitrogen Oxides (NOx)

  8. ICARTT Campaign Over and Downwind of Eastern North America in Summer 2004 Aircraft Flight Tracks and Validation LocationsOverlaid on SCIAMACHY Tropospheric NO2 Columns NASA DC-8 NOAA WP-3D Martin et al., 2006

  9. Significant Agreement Between Coincident Cloud-Filtered SCIAMACHY and In-Situ Measurements r = 0.77 slope = 0.82 1:1 line Cloud-radiance fraction < 0.5 In-situ measurements below 1 km & above 3 km Assume constant mixing ratio below lowest measurement Add upper tropospheric profile from mean obs Cohen (DC-8) Ryerson (WP-3D) Horizontal bars show 17th & 83rd percentiles Martin et al., 2006

  10. Conduct a Chemical Inversion For NOx Emissions min cost function A Priori NOx Emissions (xa) SCIAMACHY NO2 Columns (y) 2004-2005 1998 1011 molec N cm-2 s-1 1015 molec N cm-2 GEOS-CHEM model F(x) Sa A posteriori emissions x Error weighting Top-Down Emissions Sy

  11. Significant Agreement Between A Priori and A PosterioriLargest Discrepancy in East Asia r=0.91 Martin et al., 2006

  12. A Posteriori NOx Emissions from East Asia Exceed Those from Either North America or Europe A priori (38 Tg N/yr) A posteriori (46 Tg N/yr)

  13. Evaluation of Modeled Spatial DistributionsNO2 Columns: Summer 2004 CMAQ SCIAMACHY molec/cm2 • On-going efforts: • Model Evaluation (2004) • Test and Improve NOx Emission Inventories Rob Pinder, Robin Dennis

  14. Evaluation of NO2 Spatial Distributions (contd.) CMAQ -SCIAMACHY CMAQ Evaluation • Comparable spatial distributions • SCIAMACHY higher in rural areas •  higher regional background • missing source (lightning) or • NOxNOy too rapid • CMAQ higher downwind of urban areas • (e.g., Atlanta, St. Louis), Point sources • air mass factor from GEOS-CHEM • NOx lifetime difference due to resolution Similar discrepancies at surface Rob Pinder, Robin Dennis

  15. Can Satellite Measurements of Tropospheric NO2 Columns Provide a Proxy for Surface NO2 In Regions Without In Situ Measurements? Highest NO2 maximum quarterly mean by county, 2001

  16. Relationship Between Surface NO2 and GOME NO2 Columns Northern Italy Fall/Winter Spring/Summer In Situ Measurements Corrected for NOy Contamination Ordonez et al., JGR, 2006

  17. Relationship Between Simulated (GEOS-Chem) and Measured NO2 Profiles over Land Texas AQS In Situ GEOS-Chem Martin et al., 2004 In Situ GEOS-Chem (standard) (lightning x 4) ICARTT Martin et al., 2006

  18. Infer Surface NO2from Tropospheric NO2 Column Using Model Vertical Profile CMAQ SCIAMACHY molec/cm2 (Courtesy: R. Martin) ppm Rob Pinder, Robin Dennis

  19. Satellite Retrieval of SO2 • Challenging! (Ozone Interference, Rayleigh Scattering <330 nm) • TOMS: detect volcanic eruptions (detection limit: 4-6 DU) [Krueger, 1983; Krueger et al., 1995] • GOME: detect both volcanic & anthropogenic SO2 [Eisinger & Burrows, 1998; Khokhar et al., 2005] using the DOAS technique (detection limit: 0.5-1 DU)

  20. Global Distribution of SO2 Columns Retrieved from GOMEMissing Source from Nyamuragira Volcano in October 1998Retrieval Issues in July? GEOS-Chem GOME Dobson Units Oct98 Oct98 Jul97 Jul97 Xiong Liu

  21. Conclusions • Top-down information from satellites can be applied to improve NOx emission inventories • OMI will provide this capability at higher resolution • Additional model development necessary for application at local scale • Encouraging prospect of inferring surface NO2 from satellite/model

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