On the enstrophy flux vector in an inviscid barotropic fluid

Autor(en)

Michael Hantel, Leopold Haimberger, Marcus Hirtl

Abstrakt

We consider a 2D-inviscid barotropic fluid with zero divergence. The velocity is represented by the wind stream function. Implicit in the motion field is the enstrophy, transported by the wind like a time-dependent tracer. We split the corresponding flux vector into its rotational and divergent component; the rotational component can be represented by another scalar stream function. This new enstrophy flux stream function comprises both the flux of a constant reference enstrophy, proportional to the wind stream function, plus the flux of eddy enstrophy. We consider the curl of the enstrophy flux vector within a rectangular horizontal domain with cyclic boundary conditions. The domain-averaged square of the curl adopts its minimum for a value of the reference enstrophy that is governed by both the domain-averaged enstrophy and the enstrophy eddies. By reducing the enstrophy flux with this unique reference enstrophy, which is an integral of the motion, the enstrophy flux stream function becomes optimally simplified. The present theory is compared with a similar approach for the zonal mean transport properties of the global atmospheric circulation. The eddy enstrophy flux in the horizontal domain has an equivalent in the vertical domain of the zonal mean circulation. However, the eddy component of the zonal mean transport consists of two different eddies that may, at least partly, cancel each other. The reason is that the zonal mean involves the three-dimensional field of the global circulation and thus has more freedom than has the circulation of a 2D-barotropic fluid. Œ Gebrušder Borntraeger, Berlin, Stuttgart 2003.

Organisation(en)

Institut für Meteorologie und Geophysik

Externe Organisation(en)

Zentralanstalt für Meteorologie und Geodynamik (ZAMG)

Journal

Meteorologische Zeitschrift

Band

12

Seiten

175-183

Anzahl der Seiten

9

ISSN

0941-2948

DOI

https://doi.org/10.1127/0941-2948/2003/0012-0175

Publikationsdatum

2003

Peer-reviewed

Ja

ÖFOS 2012

1030 Physik, Astronomie

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/on-the-enstrophy-flux-vector-in-an-inviscid-barotropic-fluid(be4f197c-2af3-4ff3-b5e8-19161469a0ea).html