@Article{AndradeCava:2018:ObAtMo,
author = "Andrade, Kelen Martins and Cavalcanti, Iracema Fonseca de
Albuquerque",
affiliation = "{Centro Nacional de Monitoramento e Alertas de Desastres Naturais
(CEMADEN)} and {Instituto Nacional de Pesquisas Espaciais
(INPE)}",
title = "Atmospheric characteristics that induce extreme precipitation in
frontal systems over Southeastern Brazil during summer:
Observations and atmospheric model simulation",
journal = "International Journal of Climatology",
year = "2018",
volume = "38",
number = "14",
pages = "5368--5385",
month = "Nov.",
keywords = "AGCM, atmospheric anomalies, cold fronts, precipitation extremes,
South America.",
abstract = "Cold fronts are the most frequent synoptic systems that affect
Southeast Brazil during the whole year. The highest frequency of
these systems at these latitudes occurs in the months of spring
(SON) and winter (JJA), but the highest associated precipitation
occurs in the spring (SON) and summer (DJF). Some of these fronts
present light rains but others cause heavy precipitation, giving
rise to flooding and landslides, mainly in the summer. Composites
of the two cases (light and heavy rainfall) are analysed for the
summer season. Large-scale and regional features are shown to
discuss the differences in precipitation. Regional differences are
seen in the position and intensity of low pressure and postfrontal
high. The differences are also associated with the humidity flux
and convergence over the region. The main difference at high
levels is the position of the frontal trough, which is close to
the region in the wet cases and displaced to the ocean in the dry
cases. Features of the Southern Annular Mode and Madden-Julian
Oscillation show opposite patterns in the two cases. These modes
of variability can modulate extra-tropical wave trains over the
Pacific, which have different behaviour downstream, over South
America and South Atlantic Ocean. The eddy kinetic energy is
stronger over Southeastern Pacific and Southern South America, and
wave activity shows energy propagation towards the continent in
the wet cases. Similar analyses with results of a global
atmospheric model show that the general atmospheric
characteristics of a frontal system are reproduced, as the
temperature gradient, the wind confluence and the ridge-trough
pair associated with the frontal system. The model represents the
differences with respect to moisture flux and the frontal trough
position, but underestimates the moisture convergence, eddy
kinetic energy and wave activity, in the wet cases.",
doi = "10.1002/joc.5744",
url = "http://dx.doi.org/10.1002/joc.5744",
issn = "0899-8418",
language = "en",
targetfile = "andrade_atmospheric.pdf",
urlaccessdate = "27 abr. 2024"
}