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Plume Fluxes in Clear and Cloudy Convective Boundary Layers

Schumann, U. and Moeng, C.-H. (1991) Plume Fluxes in Clear and Cloudy Convective Boundary Layers. Journal of the Atmospheric Sciences, 48, pp. 1746-1757. DOI: 10.1175/1520-0469(1991)048<1746:PFICAC>2.0.CO;2

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Official URL: http://ams.allenpress.com/perlserv/?request=get-archive&issn=1520-0469

Abstract

From results of large-eddy simulations of the clear convective boundary layer and of a stratus-topped boundary layer, mean properties of “plumes” that consist of “updrafts” and “downdrafts” are determined. The plumes are defined locally by the sign of the vertical velocity or of moisture fluctuation or by a combination of both. As a further alternative, updraft and downdrafts in which the vertical velocity magnitude exceeds certain threshold values are considered. The first two variants divide the motion field into two streams, whereas in the other variants “environmental” air forms a separate stream. The computed mean properties are in general agreement with existing measurements. From the results we compute mean vertical fluxes assuming “top-hat profiles” and compare these with the actual fluxes. It is shown that the most uniform flux approximation is obtained if the plume structure is classified in terms of vertical velocity w. For such “w plumes,” the top-hat profiles approximate about 60% of the actual fluxes if updrafts and downdrafts are distinguished with zero threshold values just according to the sign of the vertical velocity. A higher percentage is obtained with nonzero threshold values.

Item URL in elib:https://elib.dlr.de/31447/
Document Type:Article
Title:Plume Fluxes in Clear and Cloudy Convective Boundary Layers
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schumann, U.UNSPECIFIEDUNSPECIFIED
Moeng, C.-H.NCAR, Boulder, CO, USAUNSPECIFIED
Date:1991
Journal or Publication Title:Journal of the Atmospheric Sciences
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:48
DOI :10.1175/1520-0469(1991)048<1746:PFICAC>2.0.CO;2
Page Range:pp. 1746-1757
Status:Published
Keywords:updrafts, downdrafts
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 Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics
Deposited By: DLR-Beauftragter, elib
Deposited On:02 Apr 2006
Last Modified:31 Jul 2019 19:17

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