Extended Abstract (108K)P3.28
Modeling turbulent airflow in mountainous regions
John Lindeman, Univ. of Leeds, Leeds, United Kingdom; and S. D. Mobbs and S. B. Vosper
Regions of complex orography such as mountains have a significant impact on local and regional scale flow. Distortion of the flow can cause orographically-induced turbulence, especially in the wake region of a mountain. Effects such as rapid distortion, where turbulence is not in local equilibrium, mean that advection and rates of strain are important factors in turbulent fluxes. Since first order closure models assume that turbulence is in local equilibrium, they cannot adequately model the turbulent structure in a mountainous region. Second order closure schemes, which are composed of prognostic equations for turbulent fluxes, are better suited to model turbulence in mountainous regions since turbulence is not assumed to be in local equilibrium. A second order turbulent closure scheme for stably stratified-flows is used to gain a better understanding of the turbulent structure in mountianous regions. Several idealised cases for two dimensional bell-shaped mountains are examined, and more complicated cases using radiosonde soundings from field experiments on the Isle of Arran, Scotland are modeled. Results from the models are also compared to corresponding aircraft measurements of mean flow and turbulent fluxes.
Poster Session 3, Topographic Flows (with Coffee Break)
Thursday, 20 June 2002, 2:45 PM-4:30 PM
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