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| Titel |
The BLLAST field experiment: Boundary-Layer Late Afternoon and Sunset Turbulence |
| VerfasserIn |
M. Lothon, F. Lohou, D. Pino, F. Couvreux, E. R. Pardyjak, J. Reuder, J. Vilà-Guerau de Arellano, P. Durand, O. Hartogensis, D. Legain, P. Augustin, B. Gioli, D. H. Lenschow, I. Faloona, C. Yagüe, D. C. Alexander, W. M. Angevine, E. Bargain, J. Barrie, E. Bazile, Y. Bezombes, E. Blay-Carreras, A. Boer, J. L. Boichard, A. Bourdon, A. Butet, B. Campistron, O. Coster, J. Cuxart, A. Dabas, C. Darbieu, K. Deboudt, H. Delbarre, S. Derrien, P. Flament, M. Fourmentin, A. Garai, F. Gibert, A. Graf, J. Groebner, F. Guichard, M. A. Jimenez, M. Jonassen, A. Kroonenberg, V. Magliulo, S. Martin, D. Martínez, L. Mastrorillo, A. F. Moene, F. Molinos, E. Moulin, H. P. Pietersen, B. Piguet, E. Pique, C. Román-Cascón, C. Rufin-Soler, F. Saïd, M. Sastre-Marugán, Y. Seity, G. J. Steeneveld, P. Toscano, O. Traullé, D. Tzanos, S. Wacker, N. Wildmann, A. Zaldei |
| 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 ; 14, no. 20 ; Nr. 14, no. 20 (2014-10-16), S.10931-10960 |
| Datensatznummer |
250119104
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| Publikation (Nr.) |
 copernicus.org/acp-14-10931-2014.pdf |
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| Zusammenfassung |
Due to the major role of the sun in heating the earth's surface, the
atmospheric planetary boundary layer over land is inherently marked by a
diurnal cycle. The afternoon transition, the period of the day that connects
the daytime dry convective boundary layer to the night-time stable boundary
layer, still has a number of unanswered scientific questions. This phase of
the diurnal cycle is challenging from both modelling and observational
perspectives: it is transitory, most of the forcings are small or null and
the turbulence regime changes from fully convective, close to homogeneous
and isotropic, toward a more heterogeneous and intermittent state.
These issues motivated the BLLAST (Boundary-Layer Late Afternoon and Sunset
Turbulence) field campaign that was conducted from 14 June to 8 July 2011 in
southern France, in an area of complex and heterogeneous terrain. A wide
range of instrumented platforms including full-size aircraft, remotely
piloted aircraft systems, remote-sensing instruments, radiosoundings,
tethered balloons, surface flux stations and various meteorological towers
were deployed over different surface types. The boundary layer, from the
earth's surface to the free troposphere, was probed during the entire day,
with a focus and intense observation periods that were conducted from midday
until sunset. The BLLAST field campaign also provided an opportunity to test
innovative measurement systems, such as new miniaturized sensors, and a new
technique for frequent radiosoundings of the low troposphere.
Twelve fair weather days displaying various meteorological conditions were
extensively documented during the field experiment. The boundary-layer
growth varied from one day to another depending on many contributions
including stability, advection, subsidence, the state of the previous day's
residual layer, as well as local, meso- or synoptic scale conditions.
Ground-based measurements combined with tethered-balloon and airborne
observations captured the turbulence decay from the surface throughout the
whole boundary layer and documented the evolution of the turbulence
characteristic length scales during the transition period.
Closely integrated with the field experiment, numerical studies are now
underway with a complete hierarchy of models to support the data
interpretation and improve the model representations. |
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