Naslov
Modeling simple katabatic flows

Autori
Grisogono, Branko ; Kavčič, Iva ; Durran, Dale ; Belušić, Danijel ; Žagar, Mark ; Enger, Leif ; Mahrt, Larry

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
EMS7/ECAM8 Abstracts / - , 2007

Skup
7th EMS Annual Meeting / 8th ECAM

Mjesto i datum
San Lorenzo de El Escorial, Španjolska, 01.10.2007. - 05.10.2007

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
Prandtl model; WKB method; Coriolis; mesoscale model; low-level jet; length scale; turbulence

Sažetak
The focus is on analytical and numerical modeling of simple katabatic flows blowing over short and long cool slopes. Since it was verified that classical scaling via Monin-Obukhov length performs over such slopes rather poorly (a low-level jet usually determines the surface fluxes), a modified Prandtl model is used instead. This linear analytic 1D model is extended for 1.) almost any gradual eddy diffusivity K(z) via the WKB method, and 2.) it includes the Coriolis effect. Its asymptotic (WKB) solution is checked against its more complete numerical solution and versus a mesoscale model (MIUU model). The Prandtl model is further used to determine one of the coefficients in the MIUU model turbulence length-scale for stable “ z-less“ conditions, L ; L = min[2a(TKE)ˆ (1/2)/N, a(TKE)ˆ (1/2)/S] where N and S are buoyancy frequency and absolute vertical wind shear and 2a = 0.537 is the standard coefficient in this higher-order turbulence closure scheme. The result can be useful in parameterizing shallow persistent katabatic flows in NWP and climate models, in data interpretation and for improving characteristic length-scales in other numerical models.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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