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Partitioning between aerosol and NO 2 absorption in UVA

Partitioning between aerosol and NO 2 absorption in UVA. N. Krotkov a , J. Herman b , A. Cede c and G. Labow c. a Goddard Earth Sciences and Technology Center, University of Maryland Baltimore County, MD USA B NASA Goddard Space Flight center, greenbelt, MD USA

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Partitioning between aerosol and NO 2 absorption in UVA

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  1. Partitioning between aerosol and NO2 absorption in UVA N. Krotkova, J. Herman b , A. Cede c and G. Labow c aGoddard Earth Sciences and Technology Center, University of Maryland Baltimore County, MD USA B NASA Goddard Space Flight center, greenbelt, MD USA C Science Systems and Applications, Inc., Lanham, MD USA

  2. Why is aerosol and NO2 UV absorption important ? Satellite (TOMS/OMI) overestimationof surface UV irradiance Aerosol effects on UV trends may enhance reduce, or reverse effects of stratospheric O3 change 22 21 + 10%-20% + 0 - 10% 23 3) Aerosol effects on photochemical smog production: aerosol scattering increases photolysis rates; while aerosol absorption decreases it: Change in boundary layer ozone mixing ratios as a result of direct aerosol forcing

  3. AEROSOL UV absorption retrievals: 2002 - 2004 UV Multifilter Rotating Shadowband Radiometer AERONET CIMEL sun-sky radiometers Brewer spectrometer : ozone, SO2, NO2 Since 2002, the NASA TOMS, AERONET and USDA UVB programs have shared equipment, personnel and analysis tools to quantify aerosol UV absorption using a combination of ground based radiation measurements and RT modeling

  4. Aerosol Single scattering albedo (= scattering /ext )

  5. absolute radiometric calibration of sky measurements (5% error) 3-min Diffuse/Total relative measurement (2% error) T text  retrieval A-priori information Fitting of absolute sky radiances in almucantar ozone k AERONET retrievals of size distribution (PSD) and effective refractive index (real) at 440nm Mie calculations PSD = const n=n440 Imaginary refr index, k, n440 Single scattering albedo,  at 325nm, 332nm and 368nm Single scattering albedo  at 440nm, 670nm ,870nm, 1020nm

  6. Figure 1, upper: Brewer direct sun NO2 retrievals [Cede and Herman, next talk: 5868-2] Upper: Typical optical depths of the main trace gases in the UV wavelength range. Lower: NO2 optical depth for 1DU, 6 Brewer mask slit positions used in NO2 retrievals

  7. 1. Single scattering albedo (= scattering/ext ) November 10 2003: a~0.1 and NO2~0.03 NO2 Amount NO2 Amount NO2 Amount

  8. 1. Single scattering albedo (= scattering/ext ) November 10 2003: a~0.1 and NO2~0.03 November 10 2003: / ~ NO2/ a~ 0.2 NO2 Amount NO2 Amount NO2 Amount

  9. 2. Single scattering albedo ( = scattering/ext ) May 13 2004: / ~ NO2/ a~ 0.03 NO2 Amount

  10. versusa (no NO2 correction) Decrease of  with ais due to uncorrected NO2 at LOW a 

  11. versusa (with NO2 correction) Retrieval with NO2

  12. versusa (325nm ) Retrieval with NO2

  13. Backup

  14. Conclusions (Future work) • Spectral overlap is needed between UV-MFRSR and CIMEL • In order to fully characterize absorption properties of the atmosphere one has to measure both NO2 and aerosol extinction () and single scattering albedo ( ). • With these new measurements we aim to discriminate between black carbon (BC) and organic carbon (OC) pollutants. • Validation of satellite UV and aerosol absorption products from TOMS and AURA/OMI

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