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Upper limit for wind shear in stably stratified conditions expressed in terms of a bulk Richardson number [in press]

Emeis, Stefan

Abstract:
Profile measurements of wind and potential temperature from a land site (obtained by a RASS for several years) and an offshore site (obtained at the meteorological mast on the research platform FINO 1 for one year) are used to analyse the temporal evolution of wind speed and wind shear under statically stable conditions, especially in situations with low-level jets. In both cases a bulk Richardson number is calculated from the data. Data analysis indicates that there seems to exist a lower bound for the bulk Richardson number during stable stratification which is greater than zero. At this lower bound the flow reaches its maximum possible vertical wind shear. Even larger shear would then mean production of new turbulence which in turn would reduce the shear. Therefore, at this lower bound, the flow is in equilibrium between production and depletion of turbulence characterized by an equilibrium Richardson number. This equilibrium Richardson number is found here at about 0.1 for the land site and 0.04 for the marine site. For situations where maximum shear occurs, this shear can be compared to the shear described by the logarithmic ve ... mehr


Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung - Atmosphärische Umweltforschung (IMK-IFU)
Publikationstyp Zeitschriftenaufsatz
Jahr 2017
Sprache Englisch
Identifikator DOI: 10.1127/metz/2017/0828
ISSN: 0941-2948, 1610-1227
KITopen ID: 1000071759
HGF-Programm 12.02.04; LK 01
Erschienen in Meteorologische Zeitschrift
Lizenz CC BY-NC 4.0: Creative Commons Namensnennung – Nicht kommerziell 4.0 International
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
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