The Turbulent Structure of the Stable, Nocturnal Boundary LayerSource: Journal of the Atmospheric Sciences:;1984:;Volume( 041 ):;issue: 014::page 2202Author:Nieuwstadt, F. T. M.
DOI: 10.1175/1520-0469(1984)041<2202:TTSOTS>2.0.CO;2Publisher: American Meteorological Society
Abstract: A large number of turbulence observations were made under stable conditions along a meteorological mast at Cabauw, The Netherlands. To present and organize these data we turn to the parameterized equations for the turbulent variances and covariances. In a dimensionless form these equations lead to a local scaling hypothesis. According to this hypothesis, dimensionless combinations of variables which are measured at the same height can be expressed as a function of a single parameter z/?. Here, ? is called a local Obukhov length and is defined as ?=?τ3/2T/(kgw?) where τ and w?) are the kinematic momentum and heat flux, respectively. Note that, in general, ? may vary across the boundary layer, because τ and w? are still unknown functions of height. The observations support local scaling. In particular, they agree with the limit condition for z/??∞, which predicts that locally scaled variables approach a constant value. The latter result is called z-less stratification. An important application of z-less stratification is that both the Richardson number and flux Richardson number should become constant in the stable boundary layer. Next we turn to the vertical profiles of τ and w?. These profiles can be obtained in principle from a simple boundary-layer model which uses as a closure hypothesis the constant Richardson number and flux Richardson number. The solution for steady-sate conditions loads to w?/w?0;=(1?z/h)) and τ/u*2=((1?z/h)3/2, where ;w?0 and u*2, are the surface temperature and momentum fluxes, respectively, and h is the boundary-layer height. Observations at Cabauw agree reasonably well with these profiles. However, they should not be considered as generally valid similarity expressions.
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contributor author | Nieuwstadt, F. T. M. | |
date accessioned | 2017-06-09T14:25:03Z | |
date available | 2017-06-09T14:25:03Z | |
date copyright | 1984/07/01 | |
date issued | 1984 | |
identifier issn | 0022-4928 | |
identifier other | ams-18881.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4154935 | |
description abstract | A large number of turbulence observations were made under stable conditions along a meteorological mast at Cabauw, The Netherlands. To present and organize these data we turn to the parameterized equations for the turbulent variances and covariances. In a dimensionless form these equations lead to a local scaling hypothesis. According to this hypothesis, dimensionless combinations of variables which are measured at the same height can be expressed as a function of a single parameter z/?. Here, ? is called a local Obukhov length and is defined as ?=?τ3/2T/(kgw?) where τ and w?) are the kinematic momentum and heat flux, respectively. Note that, in general, ? may vary across the boundary layer, because τ and w? are still unknown functions of height. The observations support local scaling. In particular, they agree with the limit condition for z/??∞, which predicts that locally scaled variables approach a constant value. The latter result is called z-less stratification. An important application of z-less stratification is that both the Richardson number and flux Richardson number should become constant in the stable boundary layer. Next we turn to the vertical profiles of τ and w?. These profiles can be obtained in principle from a simple boundary-layer model which uses as a closure hypothesis the constant Richardson number and flux Richardson number. The solution for steady-sate conditions loads to w?/w?0;=(1?z/h)) and τ/u*2=((1?z/h)3/2, where ;w?0 and u*2, are the surface temperature and momentum fluxes, respectively, and h is the boundary-layer height. Observations at Cabauw agree reasonably well with these profiles. However, they should not be considered as generally valid similarity expressions. | |
publisher | American Meteorological Society | |
title | The Turbulent Structure of the Stable, Nocturnal Boundary Layer | |
type | Journal Paper | |
journal volume | 41 | |
journal issue | 14 | |
journal title | Journal of the Atmospheric Sciences | |
identifier doi | 10.1175/1520-0469(1984)041<2202:TTSOTS>2.0.CO;2 | |
journal fristpage | 2202 | |
journal lastpage | 2216 | |
tree | Journal of the Atmospheric Sciences:;1984:;Volume( 041 ):;issue: 014 | |
contenttype | Fulltext |