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Parametrization of Surface Albedo for Nadir Aerosol Retrieval SYNAER

Kosmale, Miriam and Popp, Thomas (2015) Parametrization of Surface Albedo for Nadir Aerosol Retrieval SYNAER. ATMOS 2015, Advances in Atmospheric Science and Apllications, 8.-12. June 2015, University of Crete, Heraklion, Greece.

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Abstract

Aerosol retrieval working in the visible channels has to deal with an ill-posed problem. AOD and surface albedo are both unknown parameters within a nadir-only aerosol retrieval as the synergistic aerosol retrieval SYNAER. SYNAER is a retrieval algorithm using a combination of radiometer and spectrometer measurements onboard the same satellite platform. In a first step the aerosol amount can only be estimated with the knowledge of the surface albedo within the visible channel. Kaufman, et al.1 introduced a linear parametrization of the albedo, which is dependent on the shortwave infrared radiometer measurement. This parametrization is a common way in the so called dark field method for aerosol retrievals2. For a general understanding of the dependences between red, near and shortwave infrared channels ASRVN datasets were analyzed. ASRVN is a MODIS based dataset of surface albedo, atmospheric corrected with adjacent AERONET aerosol measurements. Additionally measured surface spectra were investigated on synthetic radiometer channels. A linear relationship between shortwave infrared (1.6 um) and red (670 nm) can be determined as Kaufman suggested, but the relationship is not constant. As suggested by Holzer-Popp2, et al. for AATSR and by Mei et al.3 for AVHRR these linear relationship can be related to the NDVI (normalized differential vegetation index). By analyzing the ASRVN and spectrometer measurements it turned out that a simple linear relationship only by using the NDVI is not sufficient for a larger variety of surface types. In order to describe the SWIR to RED dependence an additional vegetation index has to be introduced. This index accounts not only for the vegetation amount of the surface as the NDVI does, but also allows a measure for the water amount of the surface, which affects the NIR and SWIR channels of a radiometer. Introducing the NDII (normalized differential infrared index) promises a more accurate determination of the RED surface reflectance based on the SWIR channel reflectance. Additionally, an analytical equation for the SWIR to RED reflectance can be derived including both vegetation indices NDVI and NDII. Nevertheless it has to be considered that the vegetation indices themselves are affected by the aerosol amount, so the approach needs their iterative correction for the aerosol impact. The extended parametrization of surface albedo is used in the synergistic aerosol retrieval. Theoretical calculations and application to satellite datasets will be discussed in the presentation.

Item URL in elib:https://elib.dlr.de/111084/
Document Type:Conference or Workshop Item (Poster)
Title:Parametrization of Surface Albedo for Nadir Aerosol Retrieval SYNAER
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Kosmale, MiriamMiriam.Kosmale (at) dlr.deUNSPECIFIED
Popp, Thomasthomas.popp (at) dlr.deUNSPECIFIED
Date:10 June 2015
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:p. 1
Status:Published
Keywords:SYNAER, Aerosol, AOD, surface parametrization, retrieval, satellite
Event Title:ATMOS 2015, Advances in Atmospheric Science and Apllications
Event Location:University of Crete, Heraklion, Greece
Event Type:international Conference
Event Dates:8.-12. June 2015
Organizer:ESA
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Datenprodukte für Klima- und Atmosphärenanwendungen (old)
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Atmosphere
Deposited By: Kosmale, Miriam
Deposited On:14 Feb 2017 08:51
Last Modified:31 Jul 2019 20:08

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