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Surrogate cloud fields generated with the Iterative Amplitude Adapted Fourier Transform algorithm

Venema, Victor and Meyer, Steffen and Gimeno-Garcia, Sebastian and Kniffka, Anke and Simmer, Clemens and Crewell, Susanne and Löhnert, Ulrich and Trautmann, Thomas and Macke, Andreas (2006) Surrogate cloud fields generated with the Iterative Amplitude Adapted Fourier Transform algorithm. Tellus A - Dynamic Meteorology and Oceanography, 58A, pp. 104-120. Tellus. doi: 10.1111/j.1600-0870.2006.00160.x.

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A new method of generating two-dimensional and three-dimensional cloud fields is presented, which share several important statistical properties with real measured cloud fields. Well-known algorithms such as the Fourier method and the Bounded Cascade method generate fields with a specified Fourier spectrum. The new iterative method allows for the specification of both the power spectrum and the amplitude distribution of the parameter of interest, e.g. the liquid water content or liquid water path. As such, the method is well suited to generate cloud fields based on measured data, and it is able to generate broken cloud fields. Important applications of such cloud fields are e.g. closure studies. The algorithm can be supplied with additional spatial constraints which can reduce the number of measured cases needed for such studies. In this study the suitability of the algorithm for radiative questions is evaluated by comparing the radiative properties of cloud fields from cloud resolving models of cumulus and stratocumulus with their surrogate fields at nadir, and for a solar zenith angle of 0° and 60°. The cumulus surrogate clouds ended up to be identical to the large eddy simulation (LES) clouds on which they are based, except for translations and reflections. The root mean square differences of the stratocumulus transmittance and reflectance fields are less than 0.03% of the radiative budget. The radiances and mean actinic fluxes fit better than 2%. These results demonstrate that these LES clouds are well described from a radiative point of view, using only a power spectrum together with an amplitude distribution.

Item URL in elib:https://elib.dlr.de/22895/
Document Type:Article
Title:Surrogate cloud fields generated with the Iterative Amplitude Adapted Fourier Transform algorithm
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Venema, VictorMeteorological Institute of Bonn UniversityUNSPECIFIEDUNSPECIFIED
Meyer, SteffenLeibniz-Institut für Meereswissenschaften KielUNSPECIFIEDUNSPECIFIED
Gimeno-Garcia, SebastianUniversity of LeipzigUNSPECIFIEDUNSPECIFIED
Kniffka, AnkeUniversity of LeipzigUNSPECIFIEDUNSPECIFIED
Simmer, ClemensMeteorological Institute of Bonn UniversityUNSPECIFIEDUNSPECIFIED
Crewell, SusanneMeteorological Institute of Bonn UniversityUNSPECIFIEDUNSPECIFIED
Löhnert, UlrichMeteorological Institute of Bonn UniversityUNSPECIFIEDUNSPECIFIED
Macke, AndreasLeibniz-Institut für Meereswissenschaften KielUNSPECIFIEDUNSPECIFIED
Journal or Publication Title:Tellus A - Dynamic Meteorology and Oceanography
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 104-120
Keywords:Radiative transfer, Statistical cloud generator, Radiative properties of clouds
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 Entwicklung von Atmosphärenprozessoren (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Rüba, Brigitte
Deposited On:23 Mar 2006
Last Modified:07 Apr 2010 10:07

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