@Article{MüllerGanPivaSilv:2015:EnWaPr,
author = "M{\"u}ller, Gabriela Viviana and Gan, Manoel Alonso and Piva,
Everson Dal and Silveira, Virginia Piccinini",
affiliation = "{} and {Instituto Nacional de Pesquisas Espaciais (INPE)}",
title = "Energetics of wave propagation leading to cold event in tropical
latitudes of South America",
journal = "Climate Dynamics",
year = "2015",
volume = "x",
keywords = "energetics, wave propagation, frost events, South America.",
abstract = "This paper presents a new vision on the cold and cool events that
affect the tropical region of South America, considering the
dynamics and the energetics of wave train propagation associated
with these systems. Through a composite analysis of meridional
winds at 300 hPa for cold (T < 0 °C) and cool (0 °C \≤ T
\≤ 2.5 °C) air incursions affecting tropical latitudes and
causing frost are studied. The cold events observed in tropical
latitudes are associated with a single Rossby wave pattern
propagating over the Pacific Ocean which drives the low level
anticyclone from the southwest of the continent to low latitudes.
This propagation involves a southern circulation due to the
meridional wind penetration and consequently cold air advection
causing temperatures to drop below 0 °C. During cool events a
subtropical wave train propagating through the Pacific Ocean is
observed, which merges before the event with a wave coming from
the subpolar latitudes of the South Atlantic Ocean. The zonal
propagation leads to the entrance of the anticyclone from the west
of the continent, and it is strengthened together with the
meridionaly extended cyclone located upstream. This configuration
causes southerly wind advection over central-southeastern Brazil
and consequently causes the temperature decrease. The energetics
shows that the cold events kinetic energy maxima are more intense
than those of cool events. For the cold events three maxima are
observed, the first (K1) and the third (K3) maxima are developed
by baroclinic conversion and ageostrophic flux convergence and the
second one (K2) by ageostrophic flux convergence. For the cool
events two maxima are found, the first maximum (K4) developed by
baroclinic conversion and the second one by ageostrophic flux
convergence.",
doi = "10.1007/s00382-015-2532-2",
url = "http://dx.doi.org/10.1007/s00382-015-2532-2",
issn = "0930-7575",
targetfile = "Muller_Energetics.pdf",
urlaccessdate = "27 abr. 2024"
}