The cessation of continuous turbulence as precursor of the very stable nocturnal boundary layer

B.J.H. Wiel, van de, A.F. Moene, H.J.J. Jonker

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

57 Citaten (Scopus)

Samenvatting

The mechanism behind the collapse of turbulence in the evening as a precursor to the onset of the very stable boundary layer is investigated. To this end a cooled, pressure-driven flow is investigated by means of a local similarity model. Simulations reveal a temporary collapse of turbulence whenever the surface heat extraction, expressed in its nondimensional form h/L, exceeds a critical value. As any temporary reduction of turbulent friction is followed by flow acceleration, the long-term state is unconditionally turbulent. In contrast, the temporary cessation of turbulence, which may actually last for several hours in the nocturnal boundary layer, can be understood from the fact that the time scale for boundary layer diffusion is much smaller than the time scale for flow acceleration. This limits the available momentum that can be used for downward heat transport. In case the surface heat extraction exceeds the so-called maximum sustainable heat flux (MSHF), the near-surface inversion rapidly increases. Finally, turbulent activity is largely suppressed by the intense density stratification that supports the emergence of a different, calmer boundary layer regime.
Originele taal-2Engels
Pagina's (van-tot)3097-3115
TijdschriftJournal of the Atmospheric Sciences
Volume69
Nummer van het tijdschrift11
DOI's
StatusGepubliceerd - 2012

Vingerafdruk Duik in de onderzoeksthema's van 'The cessation of continuous turbulence as precursor of the very stable nocturnal boundary layer'. Samen vormen ze een unieke vingerafdruk.

Citeer dit