Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 422844
Title The collapse of turbulence in the evening
Author(s) Wiel, B.J.H. van de; Moene, A.F.; Jonker, H.J.J.; Baas, P.; Basu, S.; Sun, J.; Holtslag, A.A.M.
Source In: Proceedings of the Workshop on Diurnal cycles and the stable boundary layer, Reading, UK, 7-10 November 2011. - Reading, UK : European Centre for Medium-Range Weather Forecasts - p. 197 - 204.
Event Reading, UK : European Centre for Medium-Range Weather Forecasts Workshop on Diurnal cycles and the stable boundary layer, Reading, UK, 2011-11-07/2011-11-10
Department(s) Meteorology and Air Quality
Publication type Contribution in proceedings
Publication year 2012
Abstract A common experience in everyday weather is the fact that near-surface wind speeds tend to weaken in the evening, particularly in fair weather conditions. This cessation of wind usually coincides with the collapse of turbulence which leads to a quiet flow near the ground. As the absence of turbulent mixing leads to cold extremes, its prediction is vital for reliable winter temperature forecasts. It is, for example, well-known that unexpected frost events can completely deregulate winter traffic and enhances the risk on calamities (Fig. 1). Yet, the physical explanation behind this phenomenon remained unknown so far. Here, we present a mechanism to explain this intriguing phenomenon by combining extensive observational analysis with new theoretical insights. We detected a remarkable constraint in the kinetic energy of the flow in response to nocturnal cooling. In turn, this results in a limit on the maximum heat that can be transported towards the earth’s surface. When the actual heat loss at the surface exceeds this maximum turbulence cannot survive the intense density stratification. By using this insight, a simple predictive tool is developed. This modeling tool shows to be successful in predicting the cessation of turbulence as observed in a unique data set from a 200m meteorological tower covering 10-years of observations.
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