Abstract:Resumo Com o objetivo de organizar o conhecimento sinótico sobre ciclones em superfície em latitudes austrais, este trabalho (o primeiro de um conjunto de dois) apresenta uma síntese das principais características de quatro tipos de ciclones: extratropical do tipo Bjerknes e Solberg, extratropical do tipo Shapiro e Keyser, tropical e subtropical. Ao longo do texto são apresentados modelos conceituais bem como os mecanismos de ciclogênese, intensificação e ciclólise de cada tipo de ciclone. As principais difere… Show more
“…Cyclones are one of the most studied atmospheric systems as they produce abrupt weather changes with great societal impacts and are a major factor in controlling the global climate [1]. Synoptic scale cyclones are normally classified as extratropical, subtropical, and tropical according to their physical characteristics [2,3]. In terms of the thermal structure, tropical cyclones have a warm core in all the troposphere, while extratropical cyclones have a cold core.…”
This work documents the main features of six subtropical cyclones occurred between the years 2010 and 2016 over the southwestern South Atlantic Ocean, near the Brazilian coast, which received names (with the exception of one) from the Brazilian Navy Hydrographic Center. The fine-resolution ERA5 reanalysis and rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM) were used to describe the synoptic environment and the adverse weather conditions during the six events. The support of a small-amplitude trough at mid-levels or a cut-off low, weak vertical wind shear, and moisture flux convergence are the main features contributing to the subtropical cyclogenesis at the surface. On the other hand, sea surface temperature (SST) presents a secondary contribution since the cyclones develop over the ocean with a wide range of SST values (from 22.5 °C to 28.6 °C in the initial phase of cyclones). The six subtropical cyclones are less deep in the atmosphere column than the tropical ones and, unlike the extratropical cyclones, they have little or no westward tilt with an increase in height. The studied subtropical cyclones produced adverse weather conditions such as (a) strong winds (reaching 17 m·s−1 at 10 m high) for a long period occurring east/southeastward of the cyclone center, and (b) high amounts of rainfall along the southeastern coast of Brazil, where the accumulated rainfall varied between 170 to 350 mm, being in most cases higher than the monthly climatology. Over the continent, the Brazilian states of Rio de Janeiro and Espírito Santo were the most affected by the intense rainfall associated with the cyclones.
“…Cyclones are one of the most studied atmospheric systems as they produce abrupt weather changes with great societal impacts and are a major factor in controlling the global climate [1]. Synoptic scale cyclones are normally classified as extratropical, subtropical, and tropical according to their physical characteristics [2,3]. In terms of the thermal structure, tropical cyclones have a warm core in all the troposphere, while extratropical cyclones have a cold core.…”
This work documents the main features of six subtropical cyclones occurred between the years 2010 and 2016 over the southwestern South Atlantic Ocean, near the Brazilian coast, which received names (with the exception of one) from the Brazilian Navy Hydrographic Center. The fine-resolution ERA5 reanalysis and rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM) were used to describe the synoptic environment and the adverse weather conditions during the six events. The support of a small-amplitude trough at mid-levels or a cut-off low, weak vertical wind shear, and moisture flux convergence are the main features contributing to the subtropical cyclogenesis at the surface. On the other hand, sea surface temperature (SST) presents a secondary contribution since the cyclones develop over the ocean with a wide range of SST values (from 22.5 °C to 28.6 °C in the initial phase of cyclones). The six subtropical cyclones are less deep in the atmosphere column than the tropical ones and, unlike the extratropical cyclones, they have little or no westward tilt with an increase in height. The studied subtropical cyclones produced adverse weather conditions such as (a) strong winds (reaching 17 m·s−1 at 10 m high) for a long period occurring east/southeastward of the cyclone center, and (b) high amounts of rainfall along the southeastern coast of Brazil, where the accumulated rainfall varied between 170 to 350 mm, being in most cases higher than the monthly climatology. Over the continent, the Brazilian states of Rio de Janeiro and Espírito Santo were the most affected by the intense rainfall associated with the cyclones.
“…(Pezza and Simmonds, 2005). Extratropical cyclones are the most common over the region (Reboita et al, 2017) and, recently, a climatology of subtropical cyclones was performed by Gozzo (2014), showing that around six subtropical cyclones per year occur over the South Atlantic.…”
Section: Pv Streamers and Pv Cutoffs Structuresmentioning
Primeiramente, agradeço a mim, por ter chegado até aqui. =) Agradeço à minha família por todo apoio e compreensão, principalmente por eu ter estado/ainda estar longe de casa há mais de 8 anos; à minha orientadora, Rosmeri Porfírio da Rocha, por ter aceitado me orientar por todos estes anos e não desistir de mim, por fazer ciência de qualidade e não desistir dela nunca; aos colegas e amigos, novos e de longa data
“…This is the conversion of available potential energy from the basic state to the disturbances. Baroclinic instabilities predominate in medium latitudes, acting in the so-called baroclinic zones, where the maximum horizontal temperature gra-dients are located and, consequently, where the jets in the high troposphere are located [3] [22]. STs were extracted from daily data at average atmospheric levels (500 hPa) of the ECHAM5/MPI-OM model and were temporarily classified using a high-pass filter to include only systems with growth and decay, at intervals smaller than six days, according to methodology previously described by [23].…”
Here we investigate the ocean-atmosphere coupling and the contribution of the Sea Surface Temperature (SST) variations in: 1) Brazil-Malvinas Confluence (BMC) region, 2) Southwest Atlantic Ocean and 3) Southern Brazil. Numerical simulations of the ECHAM5/MPI-OM coupled ocean-atmosphere model were used to analyze the changes in the seasonal trajectory of the extratropical cyclones, in terms of intensification of physical mechanisms and implications for future scenarios. The numerical experiment for the future scenario considered an atmospheric CO 2 concentration of approximately 770 ppm, which represents an increment of more than 350 ppm over the current values recorded by the Mauna Loa reference station. For this scenario, the results indicated a Storm Tracks (ST) displacement of 5˚ latitude toward south and changes of the meridional transport of sensible heat, close to 50˚S. The increase in SST induces ST intensification and consequently an increase in the occurrence of extratropical cyclones. Overall, in the BMC region, we found a change in the pattern of cyclogenetic activity occurrence, with less frequent, but more intense events. On the Southern Brazilian region, the results of this study indicate increases in rainfall during summer months, whereas, a decrease in frequency and an increase in intensity were found for wintertime. We suggest that these changes could impact the climate dynamic of the Brazilian South coast, with a magnitude yet unknown.
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