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- Mohr, Matthias
(författare)
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Mesoscale Simulations of Atmospheric Flow in Complex Terrain
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The MIUU mesoscale model was further developed, in order to include information on large-scale atmospheric fields from global or regional atmospheric climate- and weather-prediction models. For this purpose, a new lateral boundary condition was developed and implemented into the model. The new lateral boundary condition is a combination of two existing conditions, namely the flow relaxation scheme and the tendency modification scheme.Tests indicated that an optimum lateral boundary configuration would be obtained with moderate to strong flow relaxation at higher levels, small flow relaxation at lower levels (within the atmospheric boundary layer), upstream advection at the outermost 4 grid points, and 6% horizontal grid stretching starting at a substantial distance from the lateral boundaries. The flow relaxation coefficients should be specified carefully, in order to minimize the reflection of all kinds of waves at the lateral boundaries.The summer thermal low in the mean-sea-level pressure field over North America is traditionally analyzed over the northern end of the Gulf of California. The position of this low is influenced by the application of the so-called plateau correction in obtaining mean-sea-level pressure values from highly elevated stations in North America. A model study indicated that the low should be located approximately 450 km to the north and somewhat to the east of the above location. A statistical comparison of model results from two mesoscale models against upper-air and surface measurements from several sites was carried out. Statistical methods, however, give only an insufficient picture of overall model performance. A comparison between predicted and measured tracer concentrations could be used to better evaluate the overall performance of different models.Sound propagation in the atmosphere was predicted in a mountain valley using a mesoscale atmospheric model together with a sound propagation model. This suggests that forecasts of sound propagation should be possible in future.
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| 2. |
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| 3. |
- Zilitinkevich, Sergej, et al.
(författare)
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An extended similarity theory for the stably stratified atmospheric surface layer
- 2000
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Ingår i: QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY. - : ROYAL METEOROLOGICAL SOC. - 0035-9009. ; 126:566, s. 1913-1923
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Tidskriftsartikel (refereegranskat)abstract
- An advanced similarity-theory formulation for the wind and temperature profiles in the stably stratified atmospheric surface layer (ASL) is developed with due regard to the effect of the free-flow static stability on the ASL. In the revised log-linear pro
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| 4. |
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| 5. |
- Zilitinkevich, Sergej
(författare)
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Non-local turbulence in stably stratified boundary layers
- 2000
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Ingår i: Advances in Turbulence VIII. Proceedings of the Eighth European Turbulence Conference (Eds. C. Dopazo et al.), CIMNE, Barcelona 2000, 311-314. ; , s. 311-314
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Zilitinkevich, Sergej, et al.
(författare)
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The effect of baroclinicity on the equilibrium depth of neutral and stable planetary boundary layers
- 2003
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Ingår i: Quarterly Journal of the Royal Meteorological Society. - : Wiley. - 0035-9009 .- 1477-870X. ; 129:595, s. 3339-3356
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Tidskriftsartikel (refereegranskat)abstract
- Earlier studies of the depths of the geophysical planetary boundary layers (PBLs) basically focused on the effects of the earth's rotation and density stratification. One more inherent feature of geophysical flows, namely their baroclinicity, has not been considered in that context. The present paper makes up for this deficiency. Diagnostic equations for the depths of the equilibrium, baroclinic, neutral or stable PBLs are derived and verified against data from large-eddy simulations (LES). These latter represents the most convenient empirical-validation tool, which allows considering separately different types of PBL: barotropic and baroclinic; truly neutral and conventionally neutral; nocturnal stable and long-lived stable. The LES are performed using a new code specifically designed for modelling the neutral and stable PBL. Results from the comparison show an excellent correspondence between the proposed equations and LES data. Copyright © 2003 Royal Meteorological Society
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