AERONET Processing Algorithms Refinement

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AERONET Processing Algorithms Refinement
AERONET Workshop May 10 - 14, 2004, El
Arenosillo, Spain
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AERONET Data Flows
http//aeronet.gsfc.nasa.gov
Holben et al. RSE, 1998 Holben et al. JGR, 2001
Flux measurements Direct - l340, 380, 440, 500,
670, 870, 940, 1020 nm Diffuse - l440, 670, 870,
1020 nm (alm, pp, pol)
Calibration and processing information
Aerosol optical depth and precipitable water
computations
Eck et al. JGR, 1999
Smirnov et al. RSE, 2000
Cloud screening and quality control
Dubovik and King JGR, 2000 Dubovik et al.JGR,
2000
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AERONET Data Flows
Current and future additions
Flux measurements Sun - l340, 380, 440, 500,
670, 870, 940, 1020 nm 1640 nm (412, 532, 555
nm) Sky - l440, 670, 870, 1020 nm 500, 1640 nm
? 340, 380 nm
Calibration and processing information H2O, CO2,
CH4
Aerosol optical depth and precipitable water
computations (1020, 1640, 940 nm) extra ta(1020
nm)
Cloud screening and quality control
Inversion products Almucantar retrievals -
spherical and spheroid models (4 wavelengths),
level 2 Almucantar retrievals - 6 wavelengths ?
340, 380 nm Principal plane retrievals - 4
wavelengths, level 2 ? 6 wavelengths ? Combined
retrievals (almucantar and principal plane)
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Current Processing Algorithm

• Extraterrestrial Solar Flux - Neckel and Labs
  1981 and Frohlich and Wehrli 1981
• Rayleigh optical depth - Edlen 1966
• Ozone amount - LUT (5ºx 5º Lat Long) - London et
  al. 1976
• Water vapor content - Bruegge et al. 1992 Reagan
  et al. 1992
• Water vapor correction for AOD (1020 nm) - none
• CO2, CH4, WV for AOD (1640 nm) - N/A

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Processing Algorithm Refinement

• Extraterrestrial Solar Flux - Woods et al. 1996
• Rayleigh optical depth - Bodhaine et al. 1999
• Ozone amount - LUT (1ºx 1º Lat Long) - TOMS data
  1979-2002
• Water vapor content - Michalsky et al. 1995
  Schmid et al. 1996
• Water vapor correction for AOD (1020 nm) - LBLRTM
• CO2, CH4, WV for AOD (1640 nm) - LBLRTM

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Extraterrestrial Solar Flux
www.astm.org
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Courtesy Dr. Jay Herman, code 916, NASA/GSFC
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Rayleigh Optical Depth
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Rayleigh Optical Depth
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V(l) V0(l)d-2 exp-mta(l)tr(l)Tw(l)
Tw(l) ? E0(l)S(l)exp-mtw(l) dl / E0(l)S(l)dl
Tw exp(-A(mu)B)
Ln V(l) mta(l)tr(l) Ln V0(l)d-2 -
A(mu)B
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Parameters A and B for various filter batches
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Optical Depth Correction at 1020 nm
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Optical Depth Correction at 1640 nm
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(No Transcript)
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AERONET Precipitable Water Comparison
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AERONET-GPS Precipitable Water Comparison
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AERONET-GPS Precipitable Water Comparison
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What to do next

• Recalibrate Master instruments (water vapor
  channel only)
• Recalculate calibration constants (water vapor
  channel only) for all instruments in the network
• Update database on water vapor content
• Quality assure PW (WVC) database
• Compare QC/QA PW with GPS and MWR retrievals