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| Titel |
Study of a prototypical convective boundary layer observed during BLLAST: contributions by large-scale forcings |
| VerfasserIn |
H. P. Pietersen, J. Vilà-Guerau de Arellano, P. Augustin, A. van de Boer, O. De Coster, H. Delbarre, P. Durand, M. Fourmentin, B. Gioli, O. Hartogensis, F. Lohou, M. Lothon, H. G. Ouwersloot, D. Pino, J. Reuder |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 8 ; Nr. 15, no. 8 (2015-04-24), S.4241-4257 |
| Datensatznummer |
250119663
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| Publikation (Nr.) |
 copernicus.org/acp-15-4241-2015.pdf |
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| Zusammenfassung |
| We study the influence of the large-scale atmospheric 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 approaches, the mixed-layer theory and large-eddy simulation (LES),
with a complete data set of surface and upper-air atmospheric 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
account, 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 correspondence of the vertical structure of
turbulent variables with observations. We also find that when large-scale
advection 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 dynamics 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. |
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