Impact of Subgrid-Scale Orography Parameterization on the Simulation of Orographic Flows

Georgelin, Marc; Richard, Évelyne; Petitdidier, Monique; Druilhet, A.

doi:10.1175/1520-0493(1994)122<1509:iossop>2.0.co;2

Cited by 53 publications

(42 citation statements)

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“…In these constricting valleys, both cold and dry winds accelerate before they reach the Mediterranean Sea at the Gulf of Lion. They are caused by similar synoptic situations, and consequently, they often coincide (Georgelin et al 1994;Guenard et al 2005). Furthermore, Mistral and Tramontane winds can increase the risk and propagation of bush fires because of the dry polar air they bring to southern France (Pugnet et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Mistral and Tramontane wind systems in climate simulations from 1950 to 2100

et al. 2017

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Section: Introductionmentioning

confidence: 99%

Mistral and Tramontane wind systems in climate simulations from 1950 to 2100

et al. 2017

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“…These consist of flow over the broad mountains only, and the corrugations are represented via an enhanced roughness length. Note that Georgelin and Richard (1994) have already suggested that the use of an effective roughness length may significantly reduce the mountain-wave amplitude. The present study allows a much more detailed assessment, since comparisons can be made with results obtained when when the small-scale orography is fully resolved.…”

Section: Representation Of Small-scale Effects By An Effective Roughnmentioning

confidence: 99%

“…The estimated values of z 0eff range from 0.1 m (the vegetative value, for H 2 = 0) to 9.2 m (when H 2 = 200 m). Note that calculating z 0eff in this way allows the exact drag exerted on the corrugations to be represented, whereas Georgelin and Richard's (1994) study relied on approximate values obtained from the Mason (1991) parametrization.…”

Section: Representation Of Small-scale Effects By An Effective Roughnmentioning

confidence: 99%

“…Smith et al, 2006;Jiang et al, 2006). In terms of how the turbulent form drag might affect the generation of mountain waves, Georgelin and Richard (1994) found that in numerical simulations the use of a form-drag parametrization scheme to represent the drag on smallscale hills can have a significant impact on the wave amplitude. The inclusion of a form-drag scheme in simulations of flow over the Pyrenees reduced the wave amplitude by as much as 50%, and this improved the accuracy of the simulated flow compared to observations.…”

Section: Introductionmentioning

confidence: 99%

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The effect of small‐scale hills on orographic drag

Brown

2007

Quart J Royal Meteoro Soc

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ABSTRACT:The purpose of this study is to investigate the extent to which the presence of hills with relatively short horizontal scales can influence the drag, due to mountain waves and flow blocking, exerted on the flow by larger-scale mountains. Numerical simulations of stratified flow over mountains are presented for flow over orography described by the linear superposition of broad mountains, whose length scales are large enough to generate mountain waves, and narrow corrugations, whose wavelengths fall below the minimum horizontal wavelength for stationary gravity waves. Results are presented for both two-and three-dimensional mountain shapes, and for a range of corrugation heights. It is shown that the corrugations can significantly reduce the amplitude of the mountain waves generated by the broader mountain, or they can suppress the unsteadiness of the wake. When these mechanisms make an important contribution to the total drag, this implies a significant drop in the total drag, compared to the sum of the contributions from the two scales of orography. From the point of view of drag parametrization, the extent to which the effect of the small-scale hills can be represented via an effective roughness length is investigated.  Crown

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“…Since this winds are caused by similar synoptic situations, they often occur at the same time (Georgelin et al, 1994;Guenard et al, 2005). They play a crucial role for deep water formation in the Gulf of Lion and for the understanding of the Mediterranean Sea circulation (Schott et al, 1996;Béranger et al, 2010).…”

Section: Introductionmentioning

confidence: 98%

Influence of sea surface roughness length parameterization on Mistral and Tramontane simulations

2016

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Abstract. The Mistral and Tramontane are mesoscale winds in southern France and above the Western Mediterranean Sea. They are phenomena well suited for studying channeling effects as well as atmosphere-land/ocean processes. This sensitivity study deals with the influence of the sea surface roughness length parameterizations on simulated Mistral and Tramontane wind speed and wind direction. Several simulations with the regional climate model COSMO-CLM were performed for the year 2005 with varying values for the Charnock parameter α. Above the western Mediterranean area, the simulated wind speed and wind direction pattern on Mistral days changes depending on the parameterization used. Higher values of α lead to lower simulated wind speeds. In areas, where the simulated wind speed does not change much, a counterclockwise rotation of the simulated wind direction is observed.

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Impact of Subgrid-Scale Orography Parameterization on the Simulation of Orographic Flows

Cited by 53 publications

References 0 publications

Mistral and Tramontane wind systems in climate simulations from 1950 to 2100

Mistral and Tramontane wind systems in climate simulations from 1950 to 2100

The effect of small‐scale hills on orographic drag

Influence of sea surface roughness length parameterization on Mistral and Tramontane simulations

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