11B.6 Vorticity dynamics in the PBL using a vector-vorticity LES model

Wednesday, 11 June 2008: 2:45 PM
Aula Magna Höger (Aula Magna)
Chin-Hoh Moeng, NCAR, Boulder, CO; and A. Arakawa, J. H. Jung, R. Rotunno, and P. P. Sullivan

The word "vorticity" is often used to define or describe turbulence

in literature. However most investigations of PBL turbulence focus

on momentum dynamics, partly because velocity is easier to measure

compared to vorticity and also because large-eddy and direct numerical

simulations typically use the momentum-pressure formulation.

In this work we pose the following questions: What are the

vorticity dynamics in the PBL and how does vorticity dynamics contribute to

turbulent transport? We use a new large-eddy simulation (LES) code

that is based on the vector-vorticity model developed by Jung and

Arakawa (2008) to investigate vorticity dynamics in the atmospheric

PBLs. The model solves vorticity equations instead of the usual

momentum equations; its output consists of all three components

of vorticity, as well as the velocity field. We use the model

to perform an LES of a convective PBL with mean shear and analyze

vortical structures that contribute to transport and

Reynolds stress in the PBL.

Jung, J.-H. and A. Arakawa, 2008: A three-dimensional anelastic model

based on the vorticity equation. Mon. Wea. Rev., 136, 276-294.

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