AERONET Processing Algorithms Refinement AERONET Workshop May 10 - 14, 2004, El Arenosillo, Spain.
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Transcript of AERONET Processing Algorithms Refinement AERONET Workshop May 10 - 14, 2004, El Arenosillo, Spain.
AERONET Processing AERONET Processing Algorithms RefinementAlgorithms Refinement
AERONET WorkshopAERONET Workshop May 10 - 14, 2004, El Arenosillo, SpainMay 10 - 14, 2004, El Arenosillo, Spain
AERONET Data FlowsAERONET Data Flowshttp://aeronet.gsfc.nasa.govhttp://aeronet.gsfc.nasa.gov
Flux measurementsFlux measurementsDirect - Direct - =340, 380, 440, 500, 670, 870, 940, 1020 nm=340, 380, 440, 500, 670, 870, 940, 1020 nmDiffuse - Diffuse - =440, 670, 870, 1020 nm (alm, pp, pol)=440, 670, 870, 1020 nm (alm, pp, pol)
Calibration and processing informationCalibration and processing information
Aerosol optical depth and Aerosol optical depth and precipitable water computationsprecipitable water computations
Holben et al.RSE, 1998
Holben et al.JGR, 2001
Holben et al.RSE, 1998
Holben et al.JGR, 2001
Smirnov et al.RSE, 2000
Smirnov et al.RSE, 2000
Dubovik and KingJGR, 2000
Dubovik et al.JGR, 2000
Dubovik and KingJGR, 2000
Dubovik et al.JGR, 2000
Cloud screening and quality controlCloud screening and quality control
Eck et al.JGR, 1999
Eck et al.JGR, 1999
Inversion productsInversion products
Volume size distribution (0.05<R<15 mm),Volume size distribution (0.05<R<15 mm),refractive index, single scattering albedorefractive index, single scattering albedo(l=440, 670, 870, 1020 nm)(l=440, 670, 870, 1020 nm)
AERONET Data Flows
Current andCurrent and futurefuture additionsadditions
Flux measurementsSun - =340, 380, 440, 500, 670, 870, 940, 1020 nm +1640 nm (412, 532, 555 nm)+1640 nm (412, 532, 555 nm)Sky - =440, 670, 870, 1020 nm ++ 500, 1640 nm500, 1640 nm + ? 340, 380 nm? 340, 380 nm
Calibration and processing information HH22O, COO, CO22, CH, CH44
Aerosol optical depth and precipitable water computations (1020, 1640, 940 nm) + extra (1020, 1640, 940 nm) + extra aa(1020 nm)(1020 nm)
Cloud screening and quality control
Inversion productsAlmucantar retrievals - spherical and spheroid models (4 wavelengths), level 2Almucantar retrievals - 6 wavelengths6 wavelengths + + ? 340, 380 nm? 340, 380 nmPrincipal plane retrievals -Principal plane retrievals - 4 wavelengths, level 2;4 wavelengths, level 2; ? 6 wavelengths ? 6 wavelengths? Combined retrievals (almucantar and principal plane)? Combined retrievals (almucantar and principal plane)
Current Processing AlgorithmCurrent 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
Processing Algorithm RefinementProcessing 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
Extraterrestrial Solar Flux
www.astm.org
600
800
1000
1200
1400
1600
0.365 0.375 0.385 0.395
US Standard (E-490)EU Standard (Wehrli 1985)Gueymard 2003Thekaekara & Drummond 1973ATLAS 3
Irradiance, W/m
2 /μm
, wavelength μm
Courtesy Dr. Jay Herman,
code 916, NASA/GSFC
-0.001
0.000
0.001
0.002
0.003
0.004
0.005
75o
60o
45o
40o
23o
10o
0o
340 nm380 nm440 nm500 nm675 nm
R( ) -new
τR
(current)
Latitude, deg
Rayleigh Optical DepthRayleigh Optical Depth
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007 340 nm380 nm440 nm500 nm675 nm
75o
60o
45o
40o
23o
10o 0
o
Latitude, deg
R( ) -new
τR
(current)
Rayleigh Optical DepthRayleigh Optical Depth
Tw = exp(-A(mu)B)
Ln V() + m[a()+r()]=
= Ln [V0()d-2] - A(mu)B
V() = V0()d-2 exp{-m[a()+r()]}Tw()
Tw() = ∫ E0()S()exp[-mw()] d
/ E0()S()d
Parameters A and B for various filter batches
0.55
0.60
0.65
0.70
0.75
0.80
0 50 100 150 200 250 300
B(2001)B(1997-1)B(1997-2)B(1998-1)B(1998-2)
filter number
B=0.574
0.55
0.60
0.65
0.70
0.75
0.80
0 50 100 150 200 250 300
A(2001)A(1997-1)A(1997-2)A(1998-1)A(1998-2)
filter number
A=0.6548
Optical Depth Correction at 1020 nmOptical Depth Correction at 1020 nm
0.000
0.005
0.010
0.015
0.020
0 2 4 6 8
Abs OD (1020 nm)
water vapor content (cm)
abs
(1020 )= 0.0023* +0.0002nm wvc
2% 5%=475 n filters
Optical Depth Correction at 1640 nmOptical Depth Correction at 1640 nm
0.000
0.005
0.010
0.015
0.020
0 2 4 6 8
Water vapor Abs OD (1640 nm)
water vapor content (cm)
abs
(1640 )= 0.0014* -0.0003nm wvc
=50 n filters 5% 2%
abs
(CO2)=0.0036
abs
(CH4)=0.0089
4.5%
AERONET Precipitable Water ComparisonAERONET Precipitable Water Comparison
0
1
2
3
4
5
6
0 1 2 3 4 5 6
water vapor content (new), cm
water vapor content (current), cm
wvc(new)=0.85wvc(current)-0.05, R=0.99
AERONET-GPS Precipitable Water ComparisonAERONET-GPS Precipitable Water Comparison
0
1
2
3
4
5
0 1 2 3 4 5
water vapor content (new), cm
water vapor content (GPS), cm
wvc(new)=0.92wvc(GPS)+0.15, R=0.99
AERONET-GPS Precipitable Water ComparisonAERONET-GPS Precipitable Water Comparison
0
1
2
3
4
5
6
0 1 2 3 4 5 6
water vapor content (GPS), cm
water vapor content (current), cm
wvc(current)=1.09wvc(GPS)+0.11, R=0.99
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