RAMAN SCATTERING IN THE EARTH’S ATMOSPHERE
RUTGER VAN DEELENJOCHEN LANDGRAF, ILSE ABEN
Photo credit: NASA
Buys Ballot
Research School
2004
Satellite measurement of backscattered sunlight
Raman scattering features
Radiative transfer model
Model result
Application of the model
Summary
OUTLINE
Sun
Earth’s
atmosphere
Earth’s
surface
SATELLITE MEASUREMENT OF
BACKSCATTERED SUNLIGHT
GOME SCIAMACHY
OMI
Sun
Earth
GOME SOLAR & EARTH SPECTRUM
GOME REFLECTIVITY SPECTRUMClear sky, the Netherlands, 1995, 0.2 nm spectral resolution
GOME REFLECTIVITY SPECTRUMClear sky, the Netherlands, 1995, 0.2 nm spectral resolution
ozone
O2
O2O2
NO2H2O
veg
etat
ion
vegetation
GOME REFLECTIVITY SPECTRUMClear sky, the Netherlands, 1995, 0.2 nm spectral resolution
ozone
O2
O2O2
NO2H2O
veg
etat
ion
vegetation
Raman
ROTATIONAL RAMAN SCATTERING
Cabannes
96 % elastic
Raman
4 % inelastic
N2, O2
at 400 nm
ROTATIONAL RAMAN SCATTERINGS
ola
r ir
rad
ian
ce
sca
tte
red
rad
ian
ce wavelength
(ir)
rad
ian
ce
wavelengthsca
tte
red
rad
ian
ce wavelength
Sun
Earth
ROTATIONAL RAMAN SCATTERINGS
ola
r ir
rad
ian
ce
wavelength
sca
tte
red
rad
ian
ce wavelength
ROTATIONAL RAMAN SCATTERINGS
ola
r ir
rad
ian
ce
refl
ecti
vit
y
RADIATIVE TRANSFERRadiative transfer equation describing multiple scattering
extinction
coefficient
intensity
source functiondistance
along path
MODEL RESULT
Total inelastic
fraction
Reflectivity
Raman features can be used to get cloud top height
Less air, less filling in
Low
cloud
High cloud
MODEL APPLICATION
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