1 / 32

Dalhousie University Department of Physics and Atmospheric Science

This research from Dalhousie University's Department of Physics and Atmospheric Science focuses on improving emission inventories by combining bottom-up and top-down approaches. The study aims to optimize the understanding of tropospheric ozone and its impact on climate and air quality.

pinkney
Download Presentation

Dalhousie University Department of Physics and Atmospheric Science

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dalhousie UniversityDepartment of Physics and Atmospheric Science Research in Theoretical, Experimental, and Applied Physics • Materials Science • Biophysics • Condensed Matter Physics • Atmospheric Science

  2. A Satellite’s View of Tropospheric Chemistry Daniel Jacob Paul Palmer Dorian Abbot Mathew Evans Kelly Chance Thomas Kurosu Randall Martin

  3. CHALLENGE FOR THE NEXT DECADE: IMPROVE EMISSION INVENTORIES “Nova Scotians with lung problems should stay inside until pollution levels drop warned Environment Canada” “Half of all Canadians live in regions failing to achieve compliance with the surface ozone standard”

  4. Stratopause Tropopause TROPOSPHERIC OZONE IS A KEY SPECIES IN CLIMATE AND AIR QUALITY • Major greenhouse gas • Primary constituent of smog • Largely controls atmospheric oxidation Mesosphere Stratosphere Ozone layer Troposphere

  5. Historical records imply a large anthropogenic contribution to the present-day tropospheric ozone background at northern midlatitudes Ozone trend from European mountain observations, 1870-1990 [Marenco et al.,1994]

  6. GLOBAL BUDGET OF TROPOSPHERIC OZONE Global sources and sinks, Tg O3 yr-1 (GEOS-CHEM model) ? Formaldehyde (HCHO) ? hv hv,H2O ? Nitrogen oxides (NOx) CO, Volatile Organic Compounds (VOCs) Ozone (O3) Hydroxyl (OH) Fires Biosphere Human activity

  7. BOTTOM-UP EMISSION INVENTORIES ARE NOTORIOUSLY DIFFICULT TO DETERMINE • Fuel use estimates • Measurements of emission ratios • Process studies • Estimate biological density • Temperature, water, … dependence of biological activity • Extreme events "Trees cause more pollution than automobiles do."

  8. HOW DO WE EVALUATE AND IMPROVE A PRIORI BOTTOM-UP INVENTORIES? Surface NOX Isoprene during July North American Isoprene Emissions (3-15 Tg C yr-1) Global NOxEmissions (Tg N yr-1) Fossil Fuel 24 (20-33) Biomass Burning 6 (3-13) Soils 5 (4-21) GEIA

  9. TOP-DOWN INFORMATION FROM THE GOME SATELLITE INSTRUMENT • Operational since 1995 • Nadir-viewing solar backscatter instrument (237-794 nm) • Low-elevation polar sun-synchronous orbit, 10:30 a.m. observation time • Spatial resolution 320x40 km2, three cross-track scenes • Complete global coverage in 3 days

  10. SPECTROSCOPY CAN BE APPLIED TO OTHER STARS AND THE EARTH’S ATMOSPHERE Figure adapted from Ian Short Weaker lines of nitrogen dioxide (NO2) and formaldehyde (HCHO)

  11. PERFORM A SPECTRAL FIT OF SOLAR BACKSCATTER OBSERVATIONS absorption Solar Io Backscattered intensity IB l1 l2 wavelength Slant optical depth “Slant column” Scattering by Earth surface and by atmosphere EARTH SURFACE

  12. USE GOME MEASUREMENTS TO RETRIEVE NO2 AND HCHO COLUMNS TO MAP NOx AND VOC EMISSIONS GOME Tropospheric NO2 column ~ ENOx Tropospheric HCHO column ~ EVOC BOUNDARY LAYER NO2 NO/NO2  W ALTITUDE NO HCHO CO OH hours hours VOC lifetime <1 day HNO3 Emission Emission NITROGEN OXIDES (NOx) VOLATILE ORGANIC COMPOUND (VOC)

  13. GOME HCHO SLANT COLUMNS (JULY 1996) Hot spots reflect high VOC emissions from fires and biosphere BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO OVER U.S. IN SUMMER K. Chance

  14. SLANT COLUMNS OF NO2 FROM GOMEDominant stratospheric structure (where NO2 is produced from N2O oxidation)Also see tropospheric hot spots (fossil fuel and biomass burning) Remove strat & instrument artifacts using obs over Pacific Martin et al., 2002

  15. SLANT COLUMNS OF TROPOSPHERIC NO2 FROM GOME 1996 Martin et al., 2002

  16. GEOS-CHEM MODEL • Assimilated Meteorology (GEOS) • 2ox2.5o horizontal resolution, 26 layers in vertical • O3-NOx-hydrocarbon chemistry • Radiative and chemical effects of aerosols • Emissions: • Fossil fuel: GEIA (NOx), Logan (CO), Piccot (NMHCs) • Biosphere: modified GEIA (hydrocarbons) & Yienger/Levy (soil NOx) • Lightning: Price/Rind/Pickering, GEOS convective cloud tops • Interannually varying biomass burning • Cross-tropopause transport • Deposition

  17. IB Io dt() EARTH SURFACE IN SCATTERING ATMOSPHERE, AMF CALCULATIONNEEDS EXTERNAL INFO ON SHAPE OF VERTICAL PROFILE RADIATIVE TRANSFER MODEL ATMOSPHERIC CHEMISTRY MODEL “a priori” Shape factor sigma () NO2 mixing ratio CNO2() norm. by columnΩNO2 Scattering weight () is temperature dependent cross-section INDIVIDUAL GOME SCENES • Calculate w() as function of: • solar and viewing zenith angle • surface albedo, pressure • cloud optical depth, pressure, frac • aerosol profile, type

  18. JULY 1996 Clear-sky NO2 AMF Fraction of IB From Clouds Actual NO2 AMF accounting for clouds Martin et al., 2002

  19. VERTICAL COLUMNS CONFINED TO REGIONS OF SURFACE EMISSIONSCloud/albedo artifacts removed by AMF calculation NO/NO2  WITH ALTITUDE NOx lifetime <1day Slant Vertical Martin et al., 2002

  20. GOME Tropospheric NO2 GEOS-CHEM Tropospheric NO2 r=0.75 bias 5% Martin et al., 2003 1015 molecules cm-2

  21. STRATEGY: OPTIMIZE INVENTORIES USING A PRIORI BOTTOM-UP AND GOME TOP-DOWN INFORMATION Top-down emissions A priori emissions A posteriori emissions Top-down errors A priori errors GOME GEOS-CHEM

  22. TOP-DOWN ERROR IN NOX EMISSIONS GOME Spectrum (423-451 nm) Spectral fit and removal of stratospheric column 1x1015 molecules cm-2 Tropospheric NO2 Slant Column AMF (surface reflectivity, clouds, aerosols, NO2 profile) 40% of tropospheric column Tropospheric NO2 Column 30% of tropospheric column NOx Lifetime (GEOS-CHEM) NOx Emissions Martin et al., 2003

  23. TOP-DOWN INFORMATION FROM GOME REDUCES ERROR IN NOX EMISSION INVENTORY Bottom-up error a Mean = 2.0 Top-down error t Mean = 2.0 Martin et al., 2003

  24. 37.7 Tg N yr-1 36.4 Tg N yr-1 OPTIMIZED NOX EMISSIONS Martin et al., 2003

  25. DIFFERENCE BETWEEN A POSTERIORI AND A PRIORI Annual mean ratio (A posteriori / A priori) Martin et al., 2003

  26. TOMS/MLS TROPOSPHERIC OZONE SUPPORTS A PRIORI BIOMASS BURNING NOX EMISSIONS HIGH OVER INDIA 30 N Dobson Units for March, April, May TOMS/MLS 30 S 30 N GEOS-CHEM Chandra et al., 2003 30 S

  27. 1997 1998 1999 2000 QUANTIFY INTERANNUAL VARIATION IN NOx EMISSIONS DJF MAM JJA SON

  28. ISOPRENE EMISSIONS FOR JULY 1996 DETERMINED FROM GOME FORMALDEHYDE COLUMNS GOME COMPARE TO… GEIA (IGAC inventory) Palmer et al., 2003

  29. EVALUATE GOME ISOPRENE INVENTORY BY COMPARISON WITH IN SITU OBSERVATIONS USING GEOS-CHEM MODEL AS INTERMEDIARY Palmer et al., 2003 CONSISTENT WITH IN-SITU HCHO OBSERVATIONS GOME (A posteriori) GEIA (A priori) r2 = 0.53 r2 = 0.77

  30. GOME HCHO COLUMNS SHOW SEASONAL VOC EMISSIONS GOME GEOS-CHEM (GEIA) GOME GEOS-CHEM (GEIA) MAR JUL APR AUG MAY SEP JUN OCT -0.5 0 1016 molec cm-2 2.0 2.5 Agreement in general pattern, regional discrepancies point to need for improving GEOS-CHEM isoprene emissions (in progress using GBEIS) Abbot et al., 2003

  31. HCHO INTERANNUAL VARIATION HIGHLY TEMPERATURE SENSITIVE 1995 1999 1996 2000 2001 1997 1998 Abbot et al., 2003

  32. PRESENT AND FUTURE SATELLITE OBSERVATIONS OF TROPOSPHERIC CHEMISTRY Increasing spatial resolution

More Related