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UV and Ozone Depletion

UV and Ozone Depletion. Ozone. Clouds are moderately well understood. Clouds. F c ~ F O3 (1 – R). Aerosols are still a major problem. Aerosols. Ozone Distribution vs Latitude (1979 to 2001). Early Observations. (c) TOMS_AI & GPCP_Precip Correlation. Detection of Aerosols is easy

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UV and Ozone Depletion

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  1. UV and Ozone Depletion Ozone Clouds are moderately well understood Clouds Fc ~ FO3(1 – R) Aerosols are still a major problem Aerosols

  2. Ozone Distribution vs Latitude (1979 to 2001)

  3. Early Observations (c) TOMS_AI & GPCP_Precip Correlation Detection of Aerosols is easy Quantification of Cloud and Aerosol effects on Climate, UV, and Health is a challenge that requires cross-cutting scientific research We need well designed programs In the laboratory, ground, and in space. H.M.S Beagle 1845 Cimel Sunphotometer Brewer Spectrometer Minimization of aerosols and UV is essential Aura 2004

  4. Software development for TOMS UV algorithm: Version 1 (V7 ozone and LER , 1995) -> Version 1.5.0 (V7 ozone, 2002) -> Version 1.5.1 (V7 ozone, 2003) -> FMI (V2)->Version 1.5.2 (V8 ozone ) ->Final ?

  5. Rationale for version 1.5.0 (2002) • New UV products: noon time spectral irradiances • UV maps and overpass products • Self-contained algorithm: OMI ready -> FMI • Remove artifacts in V1 UV web product • Improve snow albedo treatment using Min Reflectivity • [Improve absorbing aerosol parameterization ] • Calculate 360nm LER for both EP and N7/TOMS data • Calculate AI(331/360) for both EP and N7/TOMS data • Include O2-O2 absorption in calculation of LER and AI • [Sun-glint screening over ocean]

  6. Daily UV maps (using L2 V7 TOMS data) 305nm 324m 380nm Erythema

  7. UV timeseries as validation and QC tool

  8. 2-dimensional CCD swath wavelength ~ 580 pixels ~ 780 pixels flight direction » 7 km/sec viewing angle ± 57 deg 12 km/24 km (binned & co-added) 13 km 2600km (2 sec flight)) OMI - Next Generation Backscatter Spectrometer 1 • UV/VIS spectrometer: 270 – 500 nm • Daily Global Coverage • Small Ground Pixels: 13x24 km2 • Spectral Resolution: ~0.5 nm, meets Nyquist

  9. OMI Spatial Capabilities • Global Mode: • Daily global coverage • Pixel size 13x24 km2 or 48x48 km2 • Zoom-in Modes: • Pixel size 13x12 km2 • Spatial zoom-in (reduced swath) • Spectral zoom-in (reduced spectrum)

  10. OMI – UV estimates key to air photochemistry modeling and health effects • UVB levels command rates of photochemical smog production • Why is UVB in polluted areas up to 30% smaller than that estimated using models? • What is UV absorption of tropospheric gases and aerosols? • Biological effects of UV: • Cancer, cataracts, immune , material damage TOMS UVB: 305 nm

  11. UV Radiation Striking the Earth’s Surface 1. Sun burn and skin cancer PHS, NIH, WHO 2. Eye cataracts PHS, NIH, WHO 3. Plant damage - Crop yields USDA 4. Food chain - Land – Oceans USDA, NOAA 5. Effect on insect population NIH, PHS, WHO

  12. Difference between Brewer and TOMS summer noon UV index values The TOMS-Brewer difference for erythemal UV irradiance is between 7.5% and 16.5% (TOMS is higher) for two thirds of all sites

  13. UV index derivation from global solar radiation and total ozone • UV at 324 nm (low ozone absorption) is determined from measurements of global solar radiation (pyranometer data), snow cover, and dew point temperature as a proxy for total water vapor content McArthur, L.J.B., V.E. Fioletov, J.B. Kerr, C.T. McElroy, and D.I. Wardle, Derivation of UV-A irradiance from pyranometer measurements, J. Geophys. Res., 104, 30139-30151, 1999 • UV index is calculated from total ozone and UV at 324 nm estimates Fioletov, V. E., L. J. B. McArthur, J. B. Kerr and D. I. Wardle, Long-term variations of UV-B irradiance over Canada estimated from Brewer observations and derived from ozone and pyranometer measurements, J. Geophys. Res., 23,009-23,027, 2001 • Summer erythemal UV can be estimated with an uncertainty of 5-6% for daily integrated values and about 4% for monthly means

  14. Derivation of UV from global solar radiation and total ozone Solar irradiance at 324 nm measured by Brewer 14 (crosses) and estimated from pyranometer data at Toronto as a function of local solar time. Monthly mean values of derived and measured CIE daily irradiation at Toronto.

  15. Measurements and pyranometer and space based simulation of the mean summer daily erythemal irradiation at Toronto

  16. Changes in UV Irradiance • Why are we interested? • Skin Cancer • Cataracts • Reduction of internal cancer by Vitamin D production • Crop Yields • Material Degradation • Reduction in Bacterial and Viral Disease Vectors • Key Factors in UV change • Cloud Cover, Aerosols, and Ozone (UV-B)

  17. Females Cancer Incidence is dependent on amount of UV exposure, life-style, and genetic factors Vitamin D 4/100,000 High Males 1.5/100,000 Low

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