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 508897
Title Early Warning Signals for Regime Transition in the Stable Boundary Layer : A Model Study
Author(s) Hooijdonk, I.G.S. van; Moene, A.F.; Scheffer, M.; Clercx, H.J.H.; Wiel, B.J.H. van de
Source Boundary-Layer Meteorology 162 (2017)2. - ISSN 0006-8314 - p. 283 - 306.
DOI https://doi.org/10.1007/s10546-016-0199-9
Department(s) Meteorology and Air Quality
WIMEK
Aquatic Ecology and Water Quality Management
Publication type Refereed Article in a scientific journal
Publication year 2017
Keyword(s) Critical regime transition - Early warning signals - Maximum sustainable heat flux - Minimum wind speed - Nocturnal boundary layer
Abstract

The evening transition is investigated in an idealized model for the nocturnal boundary layer. From earlier studies it is known that the nocturnal boundary layer may manifest itself in two distinct regimes, depending on the ambient synoptic conditions: strong-wind or overcast conditions typically lead to weakly stable, turbulent nights; clear-sky and weak-wind conditions, on the other hand, lead to very stable, weakly turbulent conditions. Previously, the dynamical behaviour near the transition between these regimes was investigated in an idealized setting, relying on Monin–Obukhov (MO) similarity to describe turbulent transport. Here, we investigate a similar set-up, using direct numerical simulation; in contrast to MO-based models, this type of simulation does not need to rely on turbulence closure assumptions. We show that previous predictions are verified, but now independent of turbulence parametrizations. Also, it appears that a regime shift to the very stable state is signaled in advance by specific changes in the dynamics of the turbulent boundary layer. Here, we show how these changes may be used to infer a quantitative estimate of the transition point from the weakly stable boundary layer to the very stable boundary layer. In addition, it is shown that the idealized, nocturnal boundary-layer system shares important similarities with generic non-linear dynamical systems that exhibit critical transitions. Therefore, the presence of other, generic early warning signals is tested as well. Indeed, indications are found that such signals are present in stably stratified turbulent flows.

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