Messung von Luftverschmutzung aus dem All

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The determination of snow albedo and aerosol
optical thickness from space in Arctic

• A. Kokhanovsky
• W. von Hoyningen-Huene, M. Schreier
• J. P. Burrows, A. Stohl

alexk_at_iup.physik.uni-bremen.de
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Introduction

• Anthropogenic activities have significantly
  changed the tropospheric chemical composition and
  also snow/ice albedo
• Future changes are expected as result of
• increasing industrial activities, population
  growth
• Measurements are needed for
• monitoring
• improvement of understanding of mechanisms
• policy support

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Global problems global observations
Dramatic change in population and their
emissions Global Transport and Transformation of
Pollution and Acid Deposition on Land and
Ocean Global Destruction of Stratospheric
Ozone Global Climate Change- Chemistry Climate
Feedback
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Nadir UV/vis Hyperspectral Satellite
Instruments(1995-2007)

• GOME
• 07.1995 06.2003 (full)
• 4 channels 240 790 nm
• 0.2 04 nm FWHM
• nadir viewing
• 320 x 40 km2 ground pixel
• sun-synchronous orbit, 1030
• global coverage in 3 days

• SCIAMACHY
• 03.2002 today
• 8 channels 240 1700 nmand 2 2.4 µm
• 0.2 04 nm (1.5 nm) FWHM
• nadir viewing limb solar / lunar occultation
• 60 x 30 km2 typical ground pixel
• sun-synchronous orbit, 1000
• global coverage in 6 days

• OMI
• imaging spectrometer
• launched 07.2004
• 13 x 24 -120 x 24 km2 ground pixel
• global coverage in 1 day

• GOME-2
• similar to GOME
• launched 10.2006
• 80 x 40 km2 ground pixel
• global coverage in 1.5 days

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AATSR and MERIS

• AATSR
• launched 03.2002
• 1x 1 km2 ground pixel
• sun-synchronous orbit, 1000
• Wavelengths
• 0.55µm
• 0.66µm
• 0.87µm
• 1.6µm
• 3.7µm
• 11 µm
• 12 µm

• MERIS
• 03.2002 today
• 15 channels (412-1000nm)
• nadir viewing
• 300 x 300m2 typical ground pixel
• sun-synchronous orbit, 1000

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MERIS imagery Spitzbergen
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MERIS
cloudy
April 25, 2006
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MERIS
cloudy
clear
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MERIS
clear
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MERIS
clear
11
clear
MERIS
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clear
MERIS
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clear
MERIS
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AATSR IR measurements
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(No Transcript)
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Calculation of Reflectance at 3.7µm
Reflectance of 3.7µm was calculated using the
approach of Spangenberg et. al, 2000. The
contrast between snow and ice is increased here
contaminated Brightness Temperature at 3.7µm
Reflectance at 3.7µm
R Reflectance B3.7 Planck function at
3.7µm T3.7 Temperature at 3.7µm T11
Temperature at 11µm S3.7 Solar constant at
3.7µm µ_0 cos solar zenith angle e3.7 snow
emmisivity
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Cloud screening examples of reflectance (3.7µm)
for examined area (80N, 26W)
28. April 2004
02. Mai 2004
Clear sky (snow)
Low clouds
Clear sky (snow)
Low clouds
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ATMOSPHERIC CORRECTION

• Aerosol optical thickness
• Atmospheric reflectance

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BAER algorithm (von Hoyningen-Huene et al., JGR,
2003) AOT retrievals
MERIS
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April 28, 2006
May 3, 2006
MERIS
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Ground measurements (Stohl et al., 2007)
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MERIS atmospheric reflectance over ocean
ocean
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The snow albedo determination from a satellite
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Rayleigh
snow albedo

ozone
over sea
from AOT (Kokhanovsky et al., 2005)
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The first snow albedo determination using MERIS
measurements
SCIA 400DU
79.8N, 24.6E
MERIS
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theory
measurements
grains a0.85mm
MERIS
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Hudson et al., 2006
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2006
ECMWFTgt0
April 26
(Law and Stohl, 2007)
May 2
MERIS
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The location of retrievals
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Conclusions

• The retrieval of snow albedo from space requires
  a thoroughly calibrated instrument
• The retrieval of soot concentration in snow from
  a satellite is a complex matter due to low
  concentrations of soot, e.g., in Arctic,
  uncertainties of atmospheric correction over
  snow, the possible reduction of snow albedo due
  to melting processes and uptake of water
• The atmospheric correction/albedo retrieval can
  be successfully accomplished for snow fields
  close to the shore

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?
clear
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clear