Izvorni znanstveni članak
THE NATURE OF TURBULENT KINETIC ENERGY IN A DEEP AND NARROW VALLEY UNDER CONVECTIVE (?) CONDITIONS
A.P. Weigel
; Institute for Atmospheric and Climate Science ETH, Zurich, Switzerland
F.K. Chow
; Atmospheric Science Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
M.W. Rotach
; Swiss Federal Office for Meteorology and Climatology,MeteoSwiss, Zurich, Switzerland
R.L. Street
; Environmental Fluid Mechanics Laboratory, Stanford University, Stanford, CA, USA
Sažetak
This contribution investigates the nature of turbulent kinetic energy (TKE) in a steep and narrow Alpine valley under fair-weather summertime conditions. The Riviera Valley in southern Switzerland has been chosen for a detailed case study, in which the evaluation of aircraft data (obtained from the MAP-Riviera field campaign) is combined with the application of high-resolution (350 m) large-eddy simulations using the model ARPS. The simulations verify what has
already been observed on the basis of measurement data: TKE profiles scale surprisingly well if the convective velocity scale w٭ is obtained from the sun-exposed eastern slope rather than from the surface directly underneath the profiles considered. ARPS is then used to evaluate the TKE-budget equation, showing that, despite sunny conditions, wind shear is the dominant production mechanism. Therefore, the surface heat fluxes (and thus w٭) on the eastern slope do not determine the TKE evolution directly but rather, as we believe, indirectly via the interaction of thermally-driven crossvalley
and along-valley flow. Excellent correlations between w2٭ and the up-valley wind speed solidify this hypothesis.
Ključne riječi
Convective boundary layer; Large-eddy simulations; Steep valley; TKE budget; Valley winds; Wind shear
Hrčak ID:
64404
URI
Datum izdavanja:
15.12.2005.
Posjeta: 728 *