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Randall Martin Aaron Van Donkelaar

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  1. Measuring Tropospheric NO2 from SCIAMACHY During INTEX and Improving NOx Emission Inventories Randall Martin Aaron Van Donkelaar Yongtao Hu Armistead Russell Chris SiorisKelly Chance Tom Ryerson Bill Brune Jack Dibb Ron Cohen UC Berkeley

  2. Spectral Fit of NO2 Distinct NO2 Spectrum Solar Io Ozone Backscattered intensity IB NO2 Scattering by Earth surface and by atmosphere Albedo A O2-O2 Nonlinear least-squares fitting Also Weak H2O line Based on Martin et al., 2002

  3. Perform a Radiative Transfer Calculation to Account for Viewing Geometry and Scattering Cloud Radiance Fraction IB,c / (IB,o + IB,c) IB,c IB,o Io • 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 q Rc Ro Pc dt Rs Based on Martin et al., 2002, 2003

  4. Data Provided for all Cloud Fractions HoweverUse of High Cloud Fraction Data Is Discouraged!Cloud Radiance Fraction <0.4 Recommended in Header FRESCO Cloud Algorithm Reality Surface

  5. Sample JPGs Provided For Each Day Missing Data: Cloudy Missing Cloud Fields Satellite Downlink Issues Typical Individual Measurement Uncertainty ±(1x1015 molec cm-2+40%) Spectral Fit Stratospheric NO2 Surface Reflectance Clouds Aerosols Assumed NO2 Profile

  6. Preliminary Comparison Between Average Assumed and Measured NO2 ProfilesNeed to Continue Analysis for Individual Flights West of -60 degrees lon, “land” East of -60 degrees lon, “ocean” GEOS-CHEM Cohen NO2 Errorbars Show 17th and 83rd percentiles

  7. Reasonable Agreement Between Coincident SCIAMACHY and In-Situ Cloud-Free MeasurementsDifficult Comparison over Source Regions Due to Ambiguous Column Below Aircraft and Spatial Heterogeneity 1:1 line r2 = 0.69 • Coincident measurements • Cloud-radiance fraction < 0.4 • In-situ measurements below 1 km • Assume constant mixing ratio below lowest measurement Cohen NO2 Ryerson NO2 Chris Sioris In situ errorbars show 17th & 83rd percentiles – not completed for DC8

  8. Cloud-filtered Tropospheric NO2 Columns Observed from the SCIAMACHY Satellite Instrument Jul-Aug 2004 ±(5x1014 molec cm-2 + 30%) detection limit

  9. SCIAMACHY Shows Elevated NOx Export from North America SCIAMACHY NO2 (1015 molec cm-2) Jul-Aug 2004 GEOS-CHEM NO2 (1015 molec cm-2) Jul-Aug 2004

  10. SCIAMACHY Shows Elevated NOx Export from North America SCIAMACHY NO2 (1015 molec cm-2) May-Oct 2004 GEOS-CHEM NO2 (1015 molec cm-2) May-Oct 2004

  11. EMIS: Emissions Mapping Integration ScienceOptimize North American NOx Emissions SCIAMACHY NO2 Columns NOx Emissions (SMOKE/G.Tech) Aug 2004 May-Oct 2004 A priori emissions (SMOKE/Russell) 1011 molec N cm-2 s-1 1015 molecules cm-2 Models-3 GEOS-CHEM Error weighting Top-Down Emissions A posteriori emissions

  12. North American NOx Emissions (May – October)Largest Change in Northeastern US Coast GEOS-CHEM (NAPAP Scaled to 1998) SCIAMACHY (2004) SCIAMACHY - NAPAP 1011 atoms N cm-2 s-1 1011 atoms N cm-2 s-1 1011 atoms N cm-2 s-1 r2= 0.85 7.6 Tg N yr-1 0.8 Tg N yr-1 8.4 Tg N yr-1

  13. Evaluate Top-Down and Bottom-Up NOx InventoriesConduct GEOS-CHEM Simulation For Each InventorySampled GEOS-CHEM Along Flight Tracks Simulation with SCIAMACHY – Original NOx Emission Inventory NOx (ppbv) HNO3 (ppbv)

  14. P3-B Measurements Support Top-Down InventoryDC-8 Measurements Inconclusive New England New England + Gulf Remote In Situ GEOS-CHEM (Top-Down) GEOS-CHEM (Bottom-up)

  15. Major Discrepancy in NOx Emissions from Megacities 48 Tg N May-Oct 2004 48 - 38 Tg N GEIA 1998