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Eigenmann, Rafael ; Metzger, Stefan ; Foken, Thomas:
Generation of free convection due to chances in the local circulation system.
In: Atmospheric Chemistry and Physics Discussions.
Bd. 9
(2009)
.
- S. 11367-11411.
ISSN 1680-7375
DOI: https://doi.org/10.5194/acpd-9-11367-2009
Abstract
Eddy-covariance and Sodar/RASS experimental measurement data of the COPS (Convective and Orographically-induced Precipitation Study) field campaign 2007 are used to investigate the generation of near-ground free convection events in the Kinzig valley, Black Forest, Southwest Germany. The measured high-quality turbulent flux data revealed free convection to be induced in situations where high buoyancy fluxes and a simultaneously occurring wind speed collapse were present. The minimum in wind speed – observable by the Sodar measurements through the whole vertical extension of the valley atmosphere – is the consequence of a thermally-induced valley wind system, which changes its wind direction from down to up-valley winds in the morning hours. Buoyant forces then dominate over shear forces within turbulence production. These situations are detected by the stability parameter (ratio of the measurementheight to the Obukhov length) calculated from directly measured turbulent fluxes. An analysis of the scales of turbulent motions during the free convection event using wavelet transform confirms the large-eddy scale character of the detected plume-like coherent structures. Regarding the entire COPS measurement period, free convection events (FCEs) in the morning hours occur on about 50% of all days.
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| Publikationsform: | Artikel in einer Zeitschrift |
|---|---|
| Begutachteter Beitrag: | Ja |
| Zusätzliche Informationen: | BAYCEER70526 |
| Institutionen der Universität: | Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Ehemalige ProfessorInnen > Professur Mikrometeorologie - Univ.-Prof. Dr. Thomas Foken Fakultäten Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Ehemalige ProfessorInnen |
| Titel an der UBT entstanden: | Ja |
| Themengebiete aus DDC: | 500 Naturwissenschaften und Mathematik |
| Eingestellt am: | 21 Aug 2015 06:49 |
| Letzte Änderung: | 09 Okt 2023 11:08 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/18436 |