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Retrieval of Aerosol Microphysical Properties from AERONET Photo-Polarimetric Measurements. 2: A New Research Algorithm and Case DemonstrationA new research algorithm is presented here as the second part of a two-part study to retrieve aerosol microphysical properties from the multispectral and multiangular photopolarimetric measurements taken by Aerosol Robotic Network's (AERONET's) new-generation Sun photometer. The algorithm uses an advanced UNified and Linearized Vector Radiative Transfer Model and incorporates a statistical optimization approach.While the new algorithmhas heritage from AERONET operational inversion algorithm in constraining a priori and retrieval smoothness, it has two new features. First, the new algorithmretrieves the effective radius, effective variance, and total volume of aerosols associated with a continuous bimodal particle size distribution (PSD) function, while the AERONET operational algorithm retrieves aerosol volume over 22 size bins. Second, our algorithm retrieves complex refractive indices for both fine and coarsemodes,while the AERONET operational algorithm assumes a size-independent aerosol refractive index. Mode-resolved refractive indices can improve the estimate of the single-scattering albedo (SSA) for each aerosol mode and thus facilitate the validation of satellite products and chemistry transport models. We applied the algorithm to a suite of real cases over Beijing_RADI site and found that our retrievals are overall consistent with AERONET operational inversions but can offer mode-resolved refractive index and SSA with acceptable accuracy for the aerosol composed by spherical particles. Along with the retrieval using both radiance and polarization, we also performed radiance-only retrieval to demonstrate the improvements by adding polarization in the inversion. Contrast analysis indicates that with polarization, retrieval error can be reduced by over 50% in PSD parameters, 10-30% in the refractive index, and 10-40% in SSA, which is consistent with theoretical analysis presented in the companion paper of this two-part study.
Document ID
20150021895
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Xu, Xiaoguang
(Nebraska Univ. Lincoln, NE, United States)
Wang, Jun
(Nebraska Univ. Lincoln, NE, United States)
Zeng, Jing
(Nebraska Univ. Lincoln, NE, United States)
Spurr, Robert
(RT Solutions, Inc. Cambridge, MA, United States)
Liu, Xiong
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Dubovik, Oleg
(Lille-1 Univ. Villeneuve-d'Asoq, France)
Li, Li
(Academia Sinica Beijing, China)
Li, Zhengqiang
(Academia Sinica Beijing, China)
Mishchenko, Michael I.
(NASA Goddard Inst. for Space Studies New York, NY United States)
Siniuk, Aliaksandr
(Science Systems and Applications, Inc. Greenbelt, MD, United States)
Holben, Brent N.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
November 25, 2015
Publication Date
July 29, 2015
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Publisher: Wiley
Volume: 120
Issue: 14
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN27547
Funding Number(s)
WBS: WBS 281945.02.03.03.27
CONTRACT_GRANT: NNG15HQ01C
Distribution Limits
Public
Copyright
Other
Keywords
aerosol retrieval algorithm
single scattering albedo
AERONET
absorption
polarization

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