A Prognostic Relationship for Entrainment Zone Thickness

Nelson, Eric; Stull, Roland B.; Eloranta, E. W.

doi:10.1175/1520-0450(1989)028<0885:aprfez>2.0.co;2

Cited by 48 publications

(46 citation statements)

References 18 publications

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“…(i) "Constant-ratio-parametrizations" assume that the entrainment-zone thickness and the entrainment velocity are directly proportional to a length scale, and to a velocity scale respectively: Boers and Eloranta (1986) Ground-based lidar in a convective boundary layer 1.57 1 0.23 Davis et al (1997) Aircraft-based lidar in a convective boundary layer 1.5 0.5 0 Boers (1989) Based on data from Deardorff et al (1980) and Boers and Eloranta (1986) 1.23 0.5 0 Nelson et al (1989) and Gryning and Batchvarova (1994) Based on data from Deardorff et al (1980) 0 .25 Sullivan et al (1998) Large-eddy simulation convective boundary layer 1 Fedorovich et al (2004) Large-eddy simulation convective boundary layer 0.5…”

Section: Previous Empirical Resultsmentioning

confidence: 99%

“…Based on the empirical results from Tables 1 and 2, m ∈ [0.17; 1]. Using ground-based aerosol lidar, Nelson et al (1989) showed a highly time-dependent behaviour of m, as a function of the state of convective boundary-layer evolution. (iv) "Extensive-stability-parametrizations" employ a relationship between the entrainmentzone thickness and a Richardson number using V = w e :…”

Section: Previous Empirical Resultsmentioning

confidence: 99%

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Convective Boundary-Layer Entrainment: Short Review and Progress using Doppler Lidar

Träumner

Kottmeier

Corsmeier

et al. 2011

Boundary-Layer Meteorol

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The entrainment of air from the free atmosphere into the convective boundary layer is reviewed and further investigated using observations from a 2 µm Doppler lidar. It is possible to observe different individual processes entraining air into the turbulent layer, which develop with varying stability of the free atmosphere. These different processes are attended by different entrainment-zone thicknesses and entrainment velocities. Four classes of entrainment parametrizations, which describe relationships between the fundamental parameters of the process, are examined. Existing relationships between entrainment-zone thickness and entrainment velocity are basically confirmed using as scaling parameters boundary-layer height and convective velocity. An increase in the correlation coefficient between stability parameters based on the stratification of the free atmosphere and entrainment velocity (and entrainment-zone thickness respectively) up to 200% was possible using more suitable length and velocity scales.

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Section: Previous Empirical Resultsmentioning

confidence: 99%

Section: Previous Empirical Resultsmentioning

confidence: 99%

Convective Boundary-Layer Entrainment: Short Review and Progress using Doppler Lidar

Träumner

Kottmeier

Corsmeier

et al. 2011

Boundary-Layer Meteorol

View full text Add to dashboard Cite

show abstract

“…The entrainment layer is the layer where the ABL air and free atmosphere air mix together. In remote sensing measurements, the entrainment layer is usually defined to be the layer possessing 5%-95% of the characteristics of the free atmosphere, such as low aerosol concentrations (Nelson et al 1989;Cohn and Angevine 2000).…”

Section: ) the One-step Idealized-profile Methodsmentioning

confidence: 99%

A Three-Step Method for Estimating the Mixing Height Using Ceilometer Data from the Helsinki Testbed

Eresmaa

Härkönen

Joffre

et al. 2012

Journal of Applied Meteorology and Climatology

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A new three-step idealized-profile method to estimate the mixing height from vertical profiles of ceilometer backscattering coefficient is developed to address the weaknesses found with such estimates that are based on the one-step idealized-profile method. This three-step idealized-profile method fits the backscattering coefficient profile of ceilometer measurements into an idealized scaled vertical profile of three error functions, thus having the potential to determine three aerosol layers (one for the surface layer, one for the mixing height, and one for the artificial layer caused by the weakened signal). This three-step idealized-profile method is tested with ceilometer and radiosounding data collected during the Helsinki Testbed campaign (2 January 2006-13 March 2007). Excluding cases with low aerosol concentration in the boundary layer, cases with clouds present, and cases with precipitation present, the resulting dataset consists of 97 simultaneous backscattering coefficient profiles and radiosoundings. The three-step method is compared with the one-step method and other commonly employed algorithms. A strong correlation (correlation coefficient r 5 0.91) between the mixing heights as determined by the three-step method using ceilometer data and those determined from radiosoundings is an improvement over the same correlation using the one-step method (r 5 0.28), as well as the other algorithms.

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“…Values spanning such a range were reported in Nelson et al (1989). They also observed and prognostically modeled the typical early morning to late afternoon hysteresis found in plots of a versus We/w..…”

Section: Entrainment Zone Shearmentioning

confidence: 63%

“…Then, al = 0.2, n = 0.4, and the barotropic EZ contribution to w., is only a few percent. But a can exceed unity during rapid entrainment into a near-neutral layer remaining from the previous day's CBL (Nelson et al 1989). …”

Section: Entrainment Zone Shearmentioning

confidence: 99%

Amending the W* Velocity Scale for Surface Layer, Entrainment Zone, and Baroclinic Shear in Mixed Forced/Free Turbulent Convection

Kamada¹

1992

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A Prognostic Relationship for Entrainment Zone Thickness

Cited by 48 publications

References 18 publications

Convective Boundary-Layer Entrainment: Short Review and Progress using Doppler Lidar

Convective Boundary-Layer Entrainment: Short Review and Progress using Doppler Lidar

A Three-Step Method for Estimating the Mixing Height Using Ceilometer Data from the Helsinki Testbed

Amending the W* Velocity Scale for Surface Layer, Entrainment Zone, and Baroclinic Shear in Mixed Forced/Free Turbulent Convection

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