Library

X
Your search history is empty.
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Stratified Atmospheric Boundary Layers and Breakdown of Models (1998)
    Springer
    Theoretical and computational fluid dynamics 11 (1998), S. 263-279 
    Details
    ISSN: 1432-2250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract: The goal of this study is to assess complications in atmospheric stable boundary layers which are not included in numerical models of the stably stratified boundary layer and to provide a formulation of surface fluxes for use in numerical models. Based on an extensive interpretive literature survey and new eddy correlation data for the stable boundary layer, this study defines two prototype stable boundary layers: the weakly stable case and the very stable case. The weakly stable boundary layer is amenable to existing models. The very stable boundary layer eludes modeling attempts due to breakdown of existing formulations of turbulence and due to features found in the atmosphere which are not normally included in models. The latter includes clear-air radiative cooling, low-level jets, surface heterogeneity, gravity waves, meandering motions, and other mesoscale motions which propagate from outside the local domain. While these mechanisms are not essential to understanding idealized or laboratory versions of the stable boundary layer, they complicate comparisons of numerical models and theories with actual atmospheric boundary layers. Statistics which describe various features of the stable boundary layer are offered for future comparison with modeling results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001620050093
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Modelling the depth of the stable boundary-layer (1981)
    Springer
    Boundary layer meteorology 21 (1981), S. 3-19 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A simple prognostic model of the depth of the stable boundary layer is developed which includes both the possibilities of growth due to entrainment and decreasing depth associated with turbulence decay. The model is designed to avoid requirement of surface fluxes and instead uses information on profiles of mean wind and temperature. Resulting coefficients for the model are estimated by comparisons with existing studies in the literature and comparison with Wangara data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119363
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Relation of slope winds to the ambient flow over gentle terrain (1990)
    Springer
    Boundary layer meteorology 53 (1990), S. 93-102 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Four years of continuous tower data collected at the Risø National Laboratory are analyzed to study the climatological influence of a gentle slope on surface winds. Under very stable nocturnal conditions, the surface air tends to flow down the slope, at least intermittently, regardless of the direction of the overlying ambient wind. With more significant upslope ambient wind and only modest stability, downslope gravity flow is normally prevented. However, the slope-buoyancy effect is still of importance in that it retards the upslope flow of cold air. This effect is of climatic importance for the data studied here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122465
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Simple formulation of heat flux in the unstable atmospheric boundary layer (1985)
    Springer
    Boundary layer meteorology 33 (1985), S. 61-75 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Abstract A formulation for the magnitude of the upward heat flux is developed for the common situation where information on temperature fluctuations is available but measurement of vertical motion fluctuations are unavailable or of inadequate quality. A relationship is also developed which allows inference of the vertical structure of the heat flux from the stability. This development uses data from the Air Mass Transformation Experiment and a number of existing studies in the literature.
    Notes: Résumé On établit ici une formulation du flux de chaleur ascendant dans le cas courant ou l'on dispose des fluctuations de température, tandis que les fluctuations du mouvement vertical ne sont pas disponibles ou sont de qualité inadéquate. On obtient également une relation qui permet de déduire la structure verticale du flux de chaleur à partir de la stabilité. Ce développement utilise les données de l'expérience ‘Air Mass Transformation Experiment’ et plusieurs études existant dans la littérature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00137036
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Observations of fluxes over heterogeneous surfaces (1994)
    Springer
    Boundary layer meteorology 67 (1994), S. 345-367 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This study analyzes data collected from repeated aircraft runs 30 m over alternating regions of irrigated and dry nonirrigated surfaces, each region on the order of 10 km across, during the California Ozone Deposition Experiment (CODE). After studying the scale dependence of the flow, the variables and their fluxes are decomposed into means for sublegs defined in terms of irrigated and nonirrigated regions and deviations from such subleg means. Since the repeated runs were flown over the same track, compositing the eight flight legs for each of the two days allows partial isolation of the influences of surface heterogeneity and transient mesoscale motions. A variance analysis is carried out to quantify the relative importance of surface heterogeneity and transient mesoscale motions on the variability of the turbulence fluxes. The momentum and ozone fluxes are more influenced by transient mesoscale motions while fluxes of heat, moisture and carbon dioxide are more influenced by surface heterogeneity. The momentum field is also influenced by a quasi-stationary mesoscale front and larger scale velocity gradients. For the present case, the mesoscale modulation of the turbulent flux is numerically more important than the direct mesoscale flux. This spatial modulation of the turbulent fluxes leads to extra Reynolds terms which act to reduce the area-averaged turbulent momentum flux and enhance the area-averaged turbulent heat flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705438
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A two-scale mixing formulation for the atmospheric boundary layer (1995)
    Springer
    Boundary layer meteorology 73 (1995), S. 91-104 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This study compares different simple mixing schemes for one-dimensional models and then focuses on the two-scale mixing approach. Two-scale mixing consists of local diffusion between adjacent grid levels and nonlocal mixing over the bulk of the boundary layer (nonlocal mixing). The latter represents nonlocal mixing by the boundary-layer scale eddies. A common example of two-scale mixing is the formulation of the turbulent heat transport in terms of an eddy diffusivity to represent small-scale diffusion and a “countergradient correction” to represent boundary-layer scale transport. Most existing two-scale approaches are applied to heat and moisture transport while momentum transport is simultaneously parameterized only in terms of a local diffusivity without nonlocal mixing. This study attempts to correct this inconsistency. The resulting model is compared with Lidar observations of spatially averaged winds which are found to be superior to radiosonde and aircraft data for determining the mean structure. The two-scale mixing correctly predicts the observed well mixed conditions for momentum while the original model based on a local diffusivity for momentum fails to produce a well mixed state. Unfortunately, the “best” value for the adjustable coefficient in the nonlocal mixing part of the two-scale approach appears to depend on baroclinity in a way which can not be completely resolved from existing data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708931
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Stratified Atmospheric Boundary Layers (1999)
    Springer
    Boundary layer meteorology 90 (1999), S. 375-396 
    Details
    ISSN: 1573-1472
    Keywords: Intermittent turbulence ; Monin–Obukhov ; Nocturnal boundary layer ; Stable boundary layer ; Surface layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Various features of different stability regimes of the stable boundary layer are discussed. Traditional layering is examined in terms of the roughness sublayer, surface layer, local similarity, z-less stratification and the region near the boundary-layer top. In the very stable case, the strongest turbulence may be detached from the surface and generated by shear associated with a low level jet, gravity waves or meandering motions. In this case, similarity theory and the traditional concept of a boundary-layer break down. The elevated turbulence may intermittently recouple to the surface. Inability to adequately measure turbulent fluxes in very stable conditions limits our knowledge of this regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001765727956
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    An observational study of the structure of the nocturnal boundary layer (1979)
    Springer
    Boundary layer meteorology 17 (1979), S. 247-264 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In an effort to describe the basic vertical structure of the nocturnal boundary layer, observations from four experiments are analyzed. During the night, the depth of significant cooling appears to increase with time while the depth of the turbulence and height of the low level wind maximum tend to remain constant or decrease with time. Since the inversion layer extends above the low level wind maximum and shear is small in the region of the low level jet, the Richardson number reaches a maximum at the jet level and then decreases again with height. As a result, turbulence is observed to be a minimum at the height of the low level wind maximum and then increases again above this height.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117983
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    A two-layer model of soil hydrology (1984)
    Springer
    Boundary layer meteorology 29 (1984), S. 1-20 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Résumé On propose un modèle d'hydrologie du sol à deux couches, spécialement élaboré pour des applications où le temps de calcul et la complexité doivent être aussi réduits que possible. Le contenu en eau du sol dans la mince couche de surface est utilisé pour évaluer l'évaporation, tandis que la réserve en eau est calculée pour la couche profonde, beaucoup plus épaisse. Afin d'estimer les erreurs de troncature et leurs effets dans le modèle à deux couches, des comparaisons sont faites avec le modèle à 100 niveaux de Boersma et al. (1983). Ces comparaisons portent sur des sols de natures variées (argile, terres végétales et sable) et incluent divers taux d'évaporation potentielle et de précipitation. Les effets des erreurs de troncature dans le modèle à 2 couches semblent peu importants par rapport à ceux associés à la mauvaise connaissance de la diffusivité hydraulique et de sa dépendance à l'égard du contenu en eau du sol. La réduction de l'influence de ces erreurs de troncature nécessite: (1) le choix d'une couche supérieure suffisamment fine; (2) le contrôle direct de l'évaporation vers l'atmosphère à partir de la répartition verticale du contenu en eau du sol; (3) l'utilisation d'une procédure particulière pour évaluer le flux d'eau entre les deux couches du sol.
    Notes: Abstract A two-layer model of soil hydrology is developed for applications where only limited computer time and complexity are allowed. Volumetric soil water is computed in a thin upper layer for use in calculation of surface evaporation. Storage of water is computed for an underlying deeper layer. In an effort to identify the influence of significant asymmetric truncation errors in the two-layer model, this model is compared with the 100-level model of Boersma et al. (1983). Comparisons are made for modelled soils with clay, loam and sand properties for various time dependencies of potential evaporation and precipitation. Truncation errors in the resulting two-layer model appear to be modest, at least compared to errors associated with difficulty in estimation of the hydraulic diffusivity and its strong dependence on soil water content. Minimization of the influence of truncation errors requires: (1) choosing the upper layer to be sufficiently thin, (2) allowing the soil water gradient to control surface evaporation directly and (3) using suitable numerical implementation of the evaluation of internal soil water flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Spatial variability of turbulent fluxes and roughness lengths in HAPEX-MOBILHY (1993)
    Springer
    Boundary layer meteorology 65 (1993), S. 381-400 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Surface-based and aircraft measured fluxes over the heterogeneous surface in HAPEX-MOBILHY are analyzed for the ten flight days when cloud cover above the boundary layer was minimal. The fair-weather climatology of the spatial variation of surface fluxes is estimated to provide an assessment of the generality of previous case studies appearing in the literature. For the 10-day averages, greater heating over the forest generates a forest breeze which leads to rising motion and a modest increase of boundary-layer cloud cover at the forest edge. The exchange coefficients and effective roughness lengths are computed for local averages (15 km scale) and for regional averages (100 km scale) intended to represent a range of grid sizes in numerical models of the atmosphere. The effective roughness length for momentum over the mixed agricultural region for both scales is on the order of 1 m, apparently due to bluff roughness effects associated with scattered trees, edges of small woods and other obstacles. This roughness length value is an order of magnitude larger than values used in numerical models for the same region, which are based on the dominant vegetation type. The spatially varying effective roughness length for heat is computed for use in those models which use surface radiation temperature to estimate surface heat flux. The effective roughness lengths for heat are found to be smaller than those typically used in numerical models of the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707034
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...