Title:
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Study of a prototypical convective boundary layer observed during BLLAST: contributions by large-scale forcings
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Author:
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Pietersen, Henk; Vilà Guerau de Arellano, Jordi; Augustin, P; van de Boer, Anneke; de Coster, Olivier; Delbarre, Hervé; Durand, Pierre; Fourmentin, M; Gioli, Beniamino; Hartogensis, Oskar; Lohou, Fabienne; Lothon, Marie; Ouwersloot, Huug; Pino González, David; Reuder, Joachim
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Other authors:
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Universitat Politècnica de Catalunya. Departament de Física Aplicada; Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids |
Abstract:
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We study the influence of the large-scale at-
mospheric contribution to the dynamics of the convective
boundary layer (CBL) in a situation observed during the
Boundary Layer Late Afternoon and Sunset Turbulence
(BLLAST) field campaign. We employ two modeling ap-
proaches, the mixed-layer theory and large-eddy simulation
(LES), with a complete data set of surface and upper-air at-
mospheric observations, to quantify the contributions of the
advection of heat and moisture, and subsidence. We find
that by only taking surface and entrainment fluxes into ac-
count, the boundary-layer height is overestimated by 70 %.
Constrained by surface and upper-air observations, we infer
the large-scale vertical motions and horizontal advection of
heat and moisture. Our findings show that subsidence has a
clear diurnal pattern. Supported by the presence of a nearby
mountain range, this pattern suggests that not only synoptic
scales exert their influence on the boundary layer, but also
mesoscale circulations. LES results show a satisfactory cor-
respondence of the vertical structure of turbulent variables
with observations. We also find that when large-scale ad-
vection and subsidence are included in the simulation, the
values for turbulent kinetic energy are lower than without
these large-scale forcings. We conclude that the prototypical
CBL is a valid representation of the boundary-layer dynam-
ics near regions characterized by complex topography and
small-scale surface heterogeneity, provided that surface- and
large-scale forcings are representative for the local boundary layer. |
Abstract:
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Peer Reviewed |
Subject(s):
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-Àrees temàtiques de la UPC::Física -Turbulent boundary layer -Boundary layer (Meteorology) -Capa límit (Meteorologia) |
Rights:
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Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
Document type:
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Article - Published version Article |
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