Nocturnal Boundary-Layer Regimes
- 1 August 1998
- journal article
- Published by Springer Science and Business Media LLC in Boundary-Layer Meteorology
- Vol. 88 (2), 255-278
- https://doi.org/10.1023/a:1001171313493
Abstract
This study analyzes turbulence data collected over a grassland site in the nocturnal boundary layer. Examination of the dependence of the nocturnal boundary layer on stability suggests three regimes: a) the weakly stable case, b) a transition stability regime where many of the variables change rapidly with increasing stability and c) the very stable case. The value of z/L where the downward heat flux is a maximum defines the stability boundary between the weakly stable and transition regimes, where L is the Obukhov length. In the present analysis, the downward heat flux reaches a maximum at z/L approximately equal to 0.05 for 10 m, although comparison with other data indicates that this is not a universal value. For weaker stability, the heat flux decreases with decreasing z/L due to weaker temperature fluctuations. In the transition stability regime, the heat flux decreases rapidly with increasing stability due to restriction of vertical velocity fluctuations by the increasing stratification. For weakly stable conditions, the variances scale according to Monin-Obukhov similarity theory. For very stable conditions, the variances are contaminated by non-turbulent horizontal motions and do not follow the scaling laws. An alternative length scale based on variances is developed which explains more of the variance of the transfer coefficients compared to the Obukhov length.Keywords
This publication has 28 references indexed in Scilit:
- Mixing height estimation from sodar data — A critical discussionAtmospheric Environment, 1997
- Review of some basic characteristics of the atmospheric surface layerBoundary-Layer Meteorology, 1996
- The significance of the dual solutions for heat fluxes measured by the temperature fluctuation method in stable conditionsBoundary-Layer Meteorology, 1995
- Large‐eddy simulation of stable atmospheric boundary layers with a revised stochastic subgrid modelQuarterly Journal of the Royal Meteorological Society, 1994
- A case study of turbulence in the stable nocturnal boundary layerBoundary-Layer Meteorology, 1990
- Nieuwstadt's stable boundary layer revisitedQuarterly Journal of the Royal Meteorological Society, 1990
- The stably stratified boundary layer over the great plainsBoundary-Layer Meteorology, 1988
- Scaling the atmospheric boundary layerBoundary-Layer Meteorology, 1986
- Some observations of turbulence structure in stable layersQuarterly Journal of the Royal Meteorological Society, 1985
- Penetrative convection at the top of a growing boundary layerQuarterly Journal of the Royal Meteorological Society, 1979