 |
| Titel |
Advective mixing in a nondivergent barotropic hurricane model |
| VerfasserIn |
B. Rutherford, G. Dangelmayr, J. Persing, W. H. Schubert, M. T. Montgomery |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 2 ; Nr. 10, no. 2 (2010-01-20), S.475-497 |
| Datensatznummer |
250007957
|
| Publikation (Nr.) |
 copernicus.org/acp-10-475-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| This paper studies Lagrangian mixing in a two-dimensional barotropic model
for hurricane-like vortices. Since such flows show high shearing in the
radial direction, particle separation across shear-lines is diagnosed through
a Lagrangian field, referred to as R-field, that measures trajectory
separation orthogonal to the Lagrangian velocity. The shear-lines are
identified with the level-contours of another Lagrangian field, referred to
as S-field, that measures the average shear-strength along a trajectory.
Other fields used for model diagnostics are the Lagrangian field of
finite-time Lyapunov exponents (FTLE-field), the Eulerian Q-field,
and the angular velocity field. Because of the high shearing, the
FTLE-field is not a suitable indicator for advective mixing, and in
particular does not exhibit ridges marking the location of finite-time stable
and unstable manifolds. The FTLE-field is similar in structure to
the radial derivative of the angular velocity. In contrast, persisting ridges
and valleys can be clearly recognized in the R-field, and their propagation
speed indicates that transport across shear-lines is caused by Rossby waves.
A radial mixing rate derived from the R-field gives a time-dependent
measure of flux across the shear-lines. On the other hand, a measured mixing
rate across the shear-lines, which counts trajectory crossings, confirms the
results from the R-field mixing rate, and shows high mixing in the eyewall
region after the formation of a polygonal eyewall, which continues until the
vortex breaks down. The location of the R-field ridges elucidates the role
of radial mixing for the interaction and breakdown of the mesovortices shown
by the model. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|