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Influence of local surface albedo variability and ice crystal shape on passive remote sensing of thin cirrus

Fricke, C. and Ehrlich, André and Jäkel, Evi and Bohn, B. and Wirth, Martin and Wendisch, Manfred (2014) Influence of local surface albedo variability and ice crystal shape on passive remote sensing of thin cirrus. Atmospheric Chemistry and Physics, 14, pp. 1943-1958. Copernicus Publications. DOI: 10.5194/acp-14-1943-2014 ISSN 1680-7316

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Official URL: http://www.atmos-chem-phys.net/14/1943/2014/acp-14-1943-2014.pdf

Abstract

Airborne measurements of solar spectral radiance reflected by cirrus are performed with the HALO-Solar Radiation (HALO-SR) instrument onboard the High Altitude and Long Range Research Aircraft (HALO) in November 2010. The data are used to quantify the influence of surface albedo variability on the retrieval of cirrus optical thickness and crystal effective radius. The applied retrieval of cirrus optical properties is based on a standard two-wavelength approach utilizing measured and simulated reflected radiance in the visible and near-infrared spectral region. Frequency distributions of the surface albedos from Moderate resolution Imaging Spectroradiometer (MODIS) satellite observations are used to compile surface-albedo-dependent lookup tables of reflected radiance. For each assumed surface albedo the cirrus optical thickness and effective crystal radius are retrieved as a function of the assumed surface albedo. The results for the cirrus optical thickness are compared to measurements from the High Spectral Resolution Lidar (HSRL). The uncertainty in cirrus optical thickness due to local variability of surface albedo in the specific case study investigated here is below 0.1 and thus less than that caused by the measurement uncertainty of both instruments. It is concluded that for the retrieval of cirrus optical thickness the surface albedo variability is negligible. However, for the retrieval of crystal effective radius, the surface albedo variability is of major importance, introducing uncertainties up to 50%. Furthermore, the influence of the bidirectional reflectance distribution function (BRDF) on the retrieval of crystal effective radius was investigated and quantified with uncertainties below 10%, which ranges below the uncertainty caused by the surface albedo variability. The comparison with the independent lidar data allowed for investigation of the role of the crystal shape in the retrieval. It is found that if assuming aggregate ice crystals, the HSRL observations fit best with the retrieved optical thickness from HALO-SR.

Item URL in elib:https://elib.dlr.de/88373/
Document Type:Article
Title:Influence of local surface albedo variability and ice crystal shape on passive remote sensing of thin cirrus
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Fricke, C.Leipzig Institute for Meteorology, University of Leipzig, GermanyUNSPECIFIED
Ehrlich, AndréLeipzig Institute for Meteorology, University of Leipzig, GermanyUNSPECIFIED
Jäkel, EviLeipzig Institute for Meteorology, University of Leipzig, GermanyUNSPECIFIED
Bohn, B.Institute for Energy and Climate Research, IEK-8, Forschungszentrum Jülich GmbH, Jülich, GermanyUNSPECIFIED
Wirth, MartinDLR, IPAUNSPECIFIED
Wendisch, ManfredLeipzig Institute for Meteorology, University of Leipzig, GermanyUNSPECIFIED
Date:20 February 2014
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:14
DOI :10.5194/acp-14-1943-2014
Page Range:pp. 1943-1958
Publisher:Copernicus Publications
ISSN:1680-7316
Status:Published
Keywords:solar radiance, airborne measurements, cirrus optical thickness
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben LIDAR-Forschung und -Entwicklung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Lidar
Deposited By: Wirth, Dr.rer.nat. Martin
Deposited On:03 Mar 2014 11:55
Last Modified:02 May 2019 14:04

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