INVESTIGADORES
VERA Carolina Susana
artículos
Título:
Influence of the intraseasonal variability on heat waves in subtropical South America
Autor/es:
CERNE, S. BIBIANA; VERA, CAROLINA
Revista:
CLIMATE DYNAMICS
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2011 vol. 36 p. 2265 - 2277
ISSN:
0930-7575
Resumen:
The influence of the intraseasonal variability on
heat wave development over subtropical South America
during austral summer is analyzed. The role of the South
Atlantic Convergence Zone (SACZ) on this development is
documented. Results show that intraseasonal variability
can explain on average at least 32% of summer temperature
variance. Moreover, 73% of the heat waves in subtropical
South America develop in association with an active
SACZ. The analysis of pentad maps shows that warm
conditions in the region under study develop in association
with the strengthening of an anticyclonic anomaly, which is
discernible over the subtropical regions at least 15 days
before temperature peak occurrence. That circulation
anomaly is embedded in a large-scale Rossby wave train
extending along the South Pacific Ocean that is linked to
convection anomalies at the equatorial western and central
Pacific Ocean. In addition, the development of the anticyclonic
circulation over subtropical South America appears
to be strengthened by the subsidence conditions promoted
by the active SACZ, which result in temperature rise in the
subtropical region under relatively dry conditions. On the
other hand, during the last 2 days of evolution, SACZ
activity weakens and the progressive temperature rise in
the region is dominated by warmer and moister air being
anomalously advected from the north. Results confirm the
important role that SACZ activity on intraseasonal time
scales has in inducing persistent circulation anomalies at
the subtropical regions that can result in the development
of persistent heat waves, and very extreme daily
temperature.