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Optical Properties of Mineral Dust Aerosol in the Thermal Infrared

Köhler, Claas (2016) Optical Properties of Mineral Dust Aerosol in the Thermal Infrared. In: AIP Conference Proceedings, 1810 (1), 050001_1-050001_4. International Radiation Symposium 2016, 16-22 April 2016, Auckland, New Zealand. DOI: 10.1063/1.4975513 ISBN 978-0-7354-1478-5

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Official URL: http://aip.scitation.org/doi/abs/10.1063/1.4975513


The optical properties of mineral dust in the thermal infrared (TIR) will be discussed based on FTIR measurements collected during the Saharan Mineral Dust Experiment 2 (SAMUM-2). The discussion will focus on the influence of particle shape, refractive index and mixture state on the upwelling and downwelling radiance in the spectral region 800-1200 cm-1 (8 – 12 µm). The downwelling radiance at the surface was measured by the author using a D&P Model 102 FTIR within the scope of SAMUM-2. Additional coincident IASI measurements have been evaluated to analyze the radiative effect at top of the atmosphere. It will be demonstrated in a couple of case studies, that dust has a distinct effect at both top and bottom of the atmosphere. Although this influence is far more pronounced at the surface, it is clearly visible in IASI spectra, too, and it may e.g. lead to a bias of approximately 1 K in retrieved sea surface temperature retrieval if not properly accounted for. Additionally our measurements confirm recent laboratory studies and field experiments which indicate that the assumption of spherical model particles is a poor choice for mineral dust. Ellipsoids with rather large aspect ratios result in a much better agreement of our measurements with radiative transfer simulations. It will be shown though, that the ellipsoid model may not be an optimal choice for dust particles either, as there still remain significant discrepancies between the microphysical properties retrieved from the ground based FTIR measurements and those determined by other SAMUM-2 groups in elaborate laboratory analysis. It is planned to present first results of ongoing radiative transfer simulations with other particle shapes, which potentially lead to a more satisfying result.

Item URL in elib:https://elib.dlr.de/102070/
Document Type:Conference or Workshop Item (Speech)
Title:Optical Properties of Mineral Dust Aerosol in the Thermal Infrared
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Köhler, Claasclaas.koehler (at) dlr.dehttps://orcid.org/0000-0003-0127-935X
Journal or Publication Title:AIP Conference Proceedings
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1063/1.4975513
Page Range:050001_1-050001_4
Series Name:Radiation Processes in the Atmosphere and Ocean (IRS2016)
Keywords:Mineral Dust; TIR; Radiative Properties; SAMUM-2; Aerosol; FTIR
Event Title:International Radiation Symposium 2016
Event Location:Auckland, New Zealand
Event Type:international Conference
Event Dates:16-22 April 2016
Organizer:University of Auckland
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 Atmosphären- und Klimaforschung
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Experimental Methods
Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Köhler, Dr. Claas Henning
Deposited On:22 Jan 2016 11:26
Last Modified:31 Jul 2019 19:59

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