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How can satellites help define the history of carbonaceous aerosols in the industrial era.

How can satellites help define the history of carbonaceous aerosols in the industrial era. Acknowledgements:

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How can satellites help define the history of carbonaceous aerosols in the industrial era.

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  1. How can satellites help define the history of carbonaceous aerosols in the industrial era. Acknowledgements: Paris Workshop - September 2003 organized by Didier Tanré and Yoram Kaufman: Slides abstracted from the talks of M. Herman (POLDER), G. De Leeuw (ATSR), O. Torres (TOMS), C. Hsu (SeaWiFs), L. Remer (MODIS) and D. Diner (MISR), G. Myhre (comparison). Carbonaceous Aerosol Workshop

  2. How can satellites help define the history of carbonaceous aerosols in the industrial era • Satellites do not measure optical depth (except for solar occultation for stratospheric aerosols) they measure reflectance • Assumptions are required about size, shape and refractive index in retrievals • More measurements reduces the number of assumptions • More measurements are: • More wavelengths • More angles • More elements in the Stokes vector (polarization) • All of the above Carbonaceous Aerosol Workshop

  3. How can satellites help define the history of carbonaceous aerosols in the industrial era • VIS/NIR/SWIR single view measurements • AVHRR on POESS, MODIS on Terra and Aqua, GLI and OCTS on ADEOS, SeaWiFS, CZCS. • Magnitude and spectral variation of radiances used to estimate size and optical depth of aerosols. • Easier over ocean where the surface has a fairly well defined contribution Carbonaceous Aerosol Workshop

  4. How can satellites help define the history of carbonaceous aerosols in the industrial era • VIS/NIR/SWIR single view measurements • Can estimate aerosol load over land • Land surface variability is a problem particularly for bright surfaces since land is generally brighter than the atmosphere but can be solved to some extent Carbonaceous Aerosol Workshop

  5. How can satellites help define the history of carbonaceous aerosols in the industrial era • VIS/NIR/SWIR single view measurements MODIS fire/smoke Aug. 23 2000 MODIS Fire Temp. Aug 23, 2000 MOPITT CO Aug 22-27 MODIS AOT Aug 23, 2000 MODIS burn scar Aug 23, 2000 Carbonaceous Aerosol Workshop

  6. How can satellites help define the history of carbonaceous aerosols in the industrial era Spring Winter Autumn Summer • VIS/NIR/SWIR single view measurements • Even over deserts blue/UV measurements can be used to estimate aerosol optical depth and single scattering albedo. *Hsu et al. 2003, submitted Carbonaceous Aerosol Workshop

  7. How can satellites help define the history of carbonaceous aerosols in the industrial era • UV measurements (340/380 nm on TOMS) • TOMS, OMI on Aura, OMPS on NPOESS. Also possible using measurements from the European GOME and SCHIAMACHY instruments. • Use effect of absorbing aerosols on the amount of molecular scattering that occurs. • Land is less of a problem than VIS/NIR because surface is dark and atmosphere is bright. Sensitive to vertical extent of aerosols. Carbonaceous Aerosol Workshop

  8. How can satellites help define the history of carbonaceous aerosols in the industrial era SeaWIFS RGB (A. Chaikovsky Minsk, Earlinet) ssa= 0.97` Sept. 4/2002 EP-TOMS TOMS-AERONET AOT comparison Carbonaceous Aerosol Workshop

  9. How can satellites help define the history of carbonaceous aerosols in the industrial era • Multi-angle measurements • POLDER - up to 14 view angles with polarization in some bands • MISR - high spatial resolution multi-angle and multi-spectral retrievals, spectral range 440-865 nm with nine view angles • ATSR, ATSR-2, AATSR on ERS satellites- broader spectral range with two view angles. • Potential to identify non-spherical particles Carbonaceous Aerosol Workshop

  10. How can satellites help define the history of carbonaceous aerosols in the industrial era • Multi-angle measurements 70º Nadir Stereo height Aerosol OD Carbonaceous Aerosol Workshop

  11. How can satellites help define the history of carbonaceous aerosols in the industrial era • Multi-angle measurements • Spectral and Directional information of ATSR-2 • Shape of the BRDF independent of the wavelength • Effects of aerosols small at 1.6 µm • Bi-modal aerosol model • Data available on TEMIS website (www.temis.nl) • Implementation DV&SV algorithms at KNMI: AOD over Europe, end 1995-early 2001 Veefkind et al., GRL vol 25, no. 16, 3135-3138, 1998 Carbonaceous Aerosol Workshop

  12. How can satellites help define the history of carbonaceous aerosols in the industrial era • Polarization measurements • POLDER - polarization measurements at 440, 670 and 865 nm with 12-15 view angles • RSP aircraft instrument, polarization measurements at from 410-2250 nm with 150 view angles. • NASA’s Glory mission (2006/2007) and APS on NPOESS (2010?). • False color images using measurements at 410, 865 and 2250 nm - left hand side is reflectance, right hand side is polarized reflectance. • Strong spectral contrast and weak variation of reflectance with scattering geometry. • Weak spectral contrast and large variation with scattering geometry of polarized reflectance • Easier to separate surface contribution from atmospheric contribution using polarized reflectance. Carbonaceous Aerosol Workshop

  13. How can satellites help define the history of carbonaceous aerosols in the industrial era • Polarization measurements • Identification of non-spherical particles more straightforward with polarization measurements, • Sensitivity of polarization to refractive index of aerosols can be used to identify aerosol type, particularly differentiation of smoke from sulfates. Carbonaceous Aerosol Workshop

  14. How can satellites help define the history of carbonaceous aerosols in the industrial era Biomass burning Mai 1997 Bréon, François-Marie, LSCE, France • Over the oceans, product of optical thickness and Angstrom coefficient • Over land, sensitive to « small aerosols » since large particles do not polarise Carbonaceous Aerosol Workshop

  15. How can satellites help define the history of carbonaceous aerosols in the industrial era • With more angles and spectral bands than POLDER retrieve a detailed aerosol model • optical depth at 0.55µm of 0.102 • a bimodal size distribution with modes of effective radius 0.35µm (water soluble) and 1.01µm (sea salt). • The spectral optical depths measured by a MFRSR (right panel) indicate that the retrieved optical depth and size distribution are realistic. Carbonaceous Aerosol Workshop

  16. How can satellites help define the history of carbonaceous aerosols in the industrial era • Retrievals (and POLDERs index) work over land because the surface polarized reflectance is grey which allows the 2250 nm polarized reflectance to be used as a proxy for the surface even when the surface albedo is bright and/or variable (e.g. at 555 and 865 nm). Including over deserts and urban areas such as LA. Carbonaceous Aerosol Workshop

  17. How can satellites help define the history of carbonaceous aerosols in the industrial era • What sort of differences do different species show in polarization? • East coast summer time haze over the Dismal swamp shows polarized reflectance increasing with frequency indicating small particles with a refractive index consistent with a hydrated salt of some kind. Carbonaceous Aerosol Workshop

  18. How can satellites help define the history of carbonaceous aerosols in the industrial era • West coast fires, 10-29-03. Size and refractive index of smoke aerosols are substantially different to the haze. Still small but appear to have very high real refractive index and single scattering albedo of order 0.9. • Implication is that POLDER should have particularly good sensitivity to smoke in its aerosol index. Carbonaceous Aerosol Workshop

  19. How can satellites help define the history of carbonaceous aerosols in the industrial era • LIDARs such as the GLAS will provide the best information on the vertical profile of aerosol opacity. Carbonaceous Aerosol Workshop

  20. How can satellites help define the history of carbonaceous aerosols in the industrial era • Retrievals use different approaches with different assumptions and biases. • What does it all mean for a scientist interested in the aerosols? • Following summary taken from Myhre et al. based on paper in press JAS 2003: • Factor of two differences • Largest uncertainty over SH high latitude ocean. • Upper limit on AOD retrievals is a problem • Biased low compared to AERONET at high optical depths Global land and ocean Global land Global ocean Carbonaceous Aerosol Workshop

  21. How can satellites help define the history of carbonaceous aerosols in the industrial era • History • TOMS and AVHRR have the longest record allowing some evaluation of inter-annual variability. • A TOMS-like record will continue because of the need for ozone monitoring. • SeaWiFS and ATSR are more recent and capable than AVHRR but precede (AD) EOS satellites. • ATSR data availability has been an issue but may be being resolved based on de Leeuw presentation. SeaWiFs data and reprocessing to do aerosols over bright surfaces is planned. • GLI, OCTS and POLDER are all of interest for aerosols but failures of ADEOS satellites limit temporal coverage. • POLDER is only space-borne polarimeter to fly around our planet. • GLI has highest spatial resolution 380 nm measurements made providing a potential improvement over information available from TOMS. Carbonaceous Aerosol Workshop

  22. How can satellites help define the history of carbonaceous aerosols in the industrial era • Presently MODIS, MISR, AATSR, Schiamachy, GOME, TOMS and AVHRR are all providing aerosol products. • In future • NASA’s A-train with a POLDER sensor, OMI (TOMS+), A-band on OCO, CALIPSO. • VIIRS and OMPS on NPP. • GOME2, other European spectrometers following on from Schiamachy? • NASA’s Glory with advanced polarization measurements • EarthCARE with HSRL? • Japanese SGLI with polarization measurements? • Advanced MISR sensor with spectral range from 380-2150 nm and polarization measurements under study. Carbonaceous Aerosol Workshop

  23. How can satellites help define the history of carbonaceous aerosols in the industrial era • Summary • Current sensors provide capability to estimate not only optical depth, but also size distribution and single scatter albedo (if enough aerosol present) over ocean and land. • Future sensors will provide speciation (in so far as an estimate of an aerosols refractive index is a useful tool for this) from polarization measurements and lidars will provide good constraints on the vertical profile of aerosols. • Primary difficulty in using products for the evaluation of aerosol transport models is understanding how the assumptions that are required in the estimate of aerosol properties interact with the assumptions in transport models. Carbonaceous Aerosol Workshop

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