A208-02
Validation of POLDER/PARASOL products from GRASP algorithm and assessment of multi-angular polarimetry potential for aerosol monitoring
Wednesday, 16 December 2020: 04:09
Virtual
Cheng Chen1,2, Oleg Dubovik2, David Fuertes1, Pavel Lytvynov1, Tatyana Lapyonok2, Anton Lopatin1, Fabrice Ducos2, Yevgeny Derimian2, Maurice Herman2, Didier Tanré2, Lorraine Remer3, Alexei Lyapustin4, Andrew M Sayer4,5, Robert C Levy4, Nai-Yung Christina Hsu4, Jacques Descloitres6, Lei Li2,7, Benjamin Torres2, Yana Karol1, Milagros Herrera2, Marcos Herreras2, Michael Aspetsberger8, Moritz Wanzenboeck8, Lukas Bindreiter8, Daniel Marth8, Andreas Hangler8 and Christian Federspiel8, (1)GRASP SAS, Remote Sensing Developments, Lille, France, (2)Laboratoire d'Optique Atmosphérique, CNRS/University of Lille, Lille, France, (3)Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD, United States, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (5)Universities Space Research Association (USRA), Columbia, MD, United States, (6)Univ. Lille, CNRS, CNES, UMS 2877 - AERIS/ICARE Data and Services Center, F-59000 Lille, Lille, France, (7)State Key Laboratory of Severe Weather (LASW) and Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing, China, (8)Cloudflight GmbH, Linz, Austria
Abstract:
The value of multi-angular spectral polarimetry for comprehensive retrieval of aerosol properties is well-established. Nevertheless, at present, practical utilization of aerosol products from polarimetry is rather limited. This is in part due to the relatively small amount of polarimetric observations compared to photometric observations, but it is also the result of the challenges in making full use of the extensive information content available in these complex observations. Indeed, while in recent years several new algorithms have been developed to provide enhanced aerosol retrievals from satellite polarimetry, the practical value of available aerosol products from polarimeters remains to be proven. In this regard, this paper presents the analysis of aerosol products obtained by the Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm from POLDER observations.
First, the validation of the entire 2005-2013 archive was conducted by comparing with AERONET data. The subjects of the validation are spectral aerosol optical depth (AOD), aerosol absorption optical depth (AAOD) and single scattering albedo (SSA) at 6 wavelengths, as well as Ångström exponent (AE), fine mode AOD (AODF) and coarse mode AOD (AODC) interpolated to the reference wavelength 550 nm. Three GRASP products were analyzed: GRASP/HP, Optimized, and Models. These different products are consistent but were obtained using different assumptions in aerosol modeling with different accuracies of atmospheric radiative transfer calculations. Second, an inter-comparison of GRASP products with the operational POLDER retrieval and three MODIS aerosol products for the year 2008 was performed.
The GRASP/Models retrievals provided the most solid AOD products. On the other hand, the detailed aerosol microphysical characteristics (AE, AODF, AODC and SSA, etc.) provided by GRASP/HP and GRASP/Optimized correlate generally better with AERONET than do the results of GRASP/Models. The comparison between GRASP and MODIS products showed that, based on validation against AERONET, the POLDER/GRASP AOD (550 nm) product is of similar and sometimes of higher quality compared to MODIS products. At the same time, the multi-angular polarimetric observations provide more information on the other advanced aerosol properties studied.
