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RAMAN SCATTERING IN THE EARTH’S ATMOSPHERE. Photo credit: NASA. RUTGER VAN DEELEN JOCHEN LANDGRAF, ILSE ABEN. Buys Ballot Research School 2004. OUTLINE. Satellite measurement of backscattered sunlight Raman scattering features Radiative transfer model Model result
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RAMAN SCATTERING IN THE EARTH’S ATMOSPHERE Photo credit: NASA RUTGER VAN DEELEN JOCHEN LANDGRAF, ILSE ABEN Buys Ballot Research School 2004
OUTLINE • Satellite measurement of backscattered sunlight • Raman scattering features • Radiative transfer model • Model result • Application of the model • Summary
SATELLITE MEASUREMENT OF BACKSCATTERED SUNLIGHT GOME SCIAMACHY OMI Sun Earth’s atmosphere Earth’s surface
GOME SOLAR & EARTH SPECTRUM Sun Earth
GOME REFLECTIVITY SPECTRUM Clear sky, the Netherlands, 1995, 0.2 nm spectral resolution
GOME REFLECTIVITY SPECTRUM Clear sky, the Netherlands, 1995, 0.2 nm spectral resolution vegetation NO2 vegetation H2O ozone O2 O2 O2
GOME REFLECTIVITY SPECTRUM Clear sky, the Netherlands, 1995, 0.2 nm spectral resolution Raman vegetation NO2 vegetation H2O ozone O2 O2 O2
ROTATIONAL RAMAN SCATTERING N2, O2 at 400 nm Cabannes 96 % elastic Raman 4 % inelastic
ROTATIONAL RAMAN SCATTERING Solar irradiance wavelength scattered radiance
ROTATIONAL RAMAN SCATTERING Solar irradiance Sun wavelength (ir)radiance Earth scattered radiance wavelength
ROTATIONAL RAMAN SCATTERING Solar irradiance wavelength reflectivity scattered radiance wavelength
RADIATIVE TRANSFER Radiative transfer equation describing multiple scattering intensity extinction coefficient distance along path source function
MODEL RESULT Reflectivity Total inelastic fraction
MODEL APPLICATION Raman features can be used to get cloud top height Low cloud High cloud Less air, less filling in
SUMMARY • Raman features are clearly visible in reflectivity spectra: can be as large as 20% • We have developed a radiative transfer model which takes Raman scattering fully into account • Raman features can be used to retrieve cloud top height
THANK YOU FOR YOUR ATTENTION R.van.Deelen@sron.nl