New Developments in AERONET aerosol retrievals

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New Developments in AERONET aerosol retrievals
Oleg Dubovik (Code 614.4)

• Outlines
• Improving operational retrieval software
• Aerosol particle non-sphericity
• Inversion of combined AERONET/satellite
  observations

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INPUT of Forward Model
Aerosol characterization form AERONET retrievals
Complex Refractive Index at l 0.44 0.67
0.87 1.02 mm
Particle Size Distribution 0.05 mm R (22 bins)
15 mm










Desert Dust
Maritime
Smoke
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AERONET Inversion 2

• Flexibility and refinements of the algorithm
• - any number of spectral channel (from 0.34
  to 1.64 mm)
• - any measurements geometry (almucantar,
  principle plane, etc.)
• - dynamic error estimates for all retrieval
  products
• - improved assumptions about surface
  reflectance (Moody et al. 2005)
• - utilizing measurements of polarization
  (not operational yet)
• New products from retrievals
• - particle non-sphericity
• - direct aerosol radiative forcing
  computations
• - degree of polarization, phase function,
  etc.
• New concepts in the retrieval
• - non-spherical aerosols
• - using co-incident satellite observations in
  the retrievals

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AERONET model of aerosol
AERONET model of aerosol
spherical
Randomly oriented spheroids (Mishchenko et al.,
1997)
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Single Scattering using spheroids
spheroid kernels data basefor operational
modeling !!!
Input wp (Np 11), V(ri) (Ni 22 -26)
K - pre-computed kernel matrices Input n and k

• Basic Model by Mishchenko et al. 1997
• randomly oriented homogeneous spheroids
• w(e) - size independent shape distribution

Time lt one sec. Accuracy lt 1-3 Range of
applicability 0.15 2pr/l 280 (26 bins) 0.4
e 2.4 (11 bins) 1.33 n 1.6 0.0005 k 0.5
Output t(l), w0(l), F11(Q), F12(Q),F22(Q), F33(Q
),F34(Q),F44(Q)
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NEW CONCEPT - retrieving degree of non-sphericity
as an additional parameter
The retrieval is possible for aerosols with
pronounced coarse fraction, i. e. desert dust and
maritime (a lt 1.2)
Retrieved aspect ratio
Non- spheres
spheres
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AERONET-MSP(multispectral polarization)

• Spectral Percent linear Polarization hourly
• Standard Products
• L(nm) 340, 380, 440, 500, 675, 870, 940, 1020,
  1640
• AERONET testing (Feb. to May 2006)
• Operational products June 2006

Dual filter wheel, top for polarizers bottom for
IAD filters
B.N. Holben
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Sensitivity of polarization to particle shape
Coarse aerosol
-P12(Q)/P11 (Q)
-P12(Q)/P11 (Q)
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e(spheroids) 5 e(spheres) 10
e(spheroids) lt 0.01 e(spheres) 0.05
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Simultaneous Inversion of intensity and
Polarization measured in principle plane at 5
channels (0.44 0.5 067 0.87 1.02)
Maarco, August 8, 2004
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Combining of observations satellite,
ground-based and aircraft
CALIPSO
CALIPSO
Retrieved

• AEROSOL
• Size Distribution
• - Real Refractive Index
• Absorption
• Vertical variability

concentration
size
altitude
concentration

• SURFACE
• Albedo
• - Bi-directional reflectance

LIDAR
LIDAR
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Simultaneous fitting
August 9, 2003 t(0.44) 0.3
AERONET
MISR-MODIS
MODIS
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Comparisons of Surface Retrievals (with improved
vertical profile)
Surface Albedo
Surface BRDF
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Surface Effect on Retrievals of the fine mode
aerosols (low aerosol loading)
POLDER June 24, 2003 t(0.44) 0.26 , SZA470
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• Version 2 operational retrieval
• More robust, more accurate and better
  characterized results
• Utilize new types of measurements (polarization,
  principle plane, etc)
• Provide new retrieval products particle shape,
  forcing, etc.
• Plans
• Using co-incident observations of MODIS, MISR and
  POLDER
• Including Lidar information into retrievals