INVESTIGADORES
VERA Carolina Susana
artículos
Título:
Characteristics of the Southern Hemisphere Winter Storm Track with Filtered and Unfiltered Data
Autor/es:
BERBERY, E. H.; VERA, CAROLINA
Revista:
JOURNAL OF THE ATMOSPHERIC SCIENCES
Editorial:
AMER METEOROLOGICAL SOC
Referencias:
Lugar: Boston; Año: 1996 vol. 53 p. 468 - 481
ISSN:
0022-4928
Resumen:
The structure and evolution of the fluctuations in synoptic scales in the Southern Hemisphere (SH) during
winter are discussed using six years of European Centre for Medium-Range Weather Forecasts analyses.
It is shown that patterns from unfiltered meridional wind series in the SH display all the features needed to
represent the synoptic-scale waves. Typical periods and wavelengths are similar to those observed in the Northern
Hemisphere (4 days, 4000 km), although over the Pacific Ocean they can be as high as 7?8 days and 4700 km,
respectively. As in the Northern Hemisphere, tilts are not geographically fixed but change with the stage of the
evolution of the wave. The phase speed of the waves agrees with the low-level winds in extensive areas of the
middle latitudes and ranges from 12 m s01 in the Indian Ocean to 6 m s01 in the Pacific Ocean. The estimated
group velocities achieve maximum values of about 38 m s01 , also in the Indian Ocean, and agree with the upperlevel
maximum winds, in accord with reported model results for the leading fringe of the wave packets.
The wave packets show a decay of upstream centers as new ones grow downstream, suggesting that downstream
development contributes to the evolution of the synoptic-scale waves in the SH storm track. This process
is observed both in the subpolar and subtropical jets, but the sequence of centers developing downstream is more
coherent in the latter, probably due to the weaker baroclinicity.