Download
1 / 15
150 likes | 271 Vues
This study examines the significance of aerosol and NO2 ultraviolet (UV) absorption in the atmosphere, highlighting its influence on satellite-derived surface UV irradiance, particularly via TOMS and OMI instruments. It addresses how aerosol effects can enhance, mitigate, or reverse trends associated with stratospheric ozone changes. Key findings include the relationship between aerosol scattering, photochemical smog production, and changes in ozone concentrations. Through ground-based measurements and modeling, the work aims to refine our understanding of atmospheric absorption properties, essential for accurate satellite product validation.
E N D
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
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
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
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
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
1. Single scattering albedo (= scattering/ext ) November 10 2003: a~0.1 and NO2~0.03 NO2 Amount NO2 Amount NO2 Amount
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
2. Single scattering albedo ( = scattering/ext ) May 13 2004: / ~ NO2/ a~ 0.03 NO2 Amount
versusa (no NO2 correction) Decrease of with ais due to uncorrected NO2 at LOW a
versusa (with NO2 correction) Retrieval with NO2
versusa (325nm ) Retrieval with NO2
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
