Climatology of extratropical cyclones over the South American–southern oceans sector

Mendes, David; Souza, Ênio Pereira de; Marengo, José A.; Mendes, Monica Cristina Damião

doi:10.1007/s00704-009-0161-6

Cited by 43 publications

(55 citation statements)

References 34 publications

(44 reference statements)

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“…This slow movement allows the SCs to interact more deeply with the environment, favoring organized convective activity, and poses a threat to the coastal regions of South America, as it causes prolonged adverse weather conditions. Mendes et al (2010) shows that during summer and autumn, at the South American coast, there is a maximum number of cyclones traveling much shorter distances than the mean for the whole Southern Hemisphere; although this was not explored in that work, it is possible that SCs contribute to the reported maximum.…”

Section: Mean Characteristicsmentioning

confidence: 71%

“…According to these works, RG1 is the genesis region of weaker cyclones that for the most part do not present a closed isobar at the sea level pressure field. That is why some climatologies based on tracking of cyclones in the sea level pressure field (e.g., Gan and Rao 1991;Mendes et al 2010) do not report this cyclogenesis region.…”

Section: Sc Spatial Density and The Importance Of Rg1 Cyclogeneticmentioning

confidence: 92%

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Subtropical Cyclones over the Southwestern South Atlantic: Climatological Aspects and Case Study

et al. 2014

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Hurricane Catarina (2004) and subtropical storm Anita (2010) called attention to the development of subtropical cyclones (SCs) over the South Atlantic basin. Besides strong and organized storms, a large number of weaker, shallower cyclones with both extratropical and tropical characteristics form in the region, impacting the South American coast. The main focus of this study is to simulate a climatology of subtropical cyclones and their synoptic pattern over the South Atlantic, proposing a broader definition of these systems. In addition, a case study is presented to discuss the main characteristics of one weak SC. The Interim ECMWF Re-Analysis (ERAInterim) and NCEP-NCAR reanalysis are used to construct the 33-yr (1979-2011) climatology, and a comparison between them is established. Both reanalyses show good agreement in the SCs' intensity, geographical distribution, and seasonal variability, but the interannual variability is poorly correlated. Anomaly composites for austral summer show that subtropical cyclogenesis occurs under a dipole-blocking pattern in upper levels. Upward motion is enhanced by the vertical temperature gradient between a midtropospheric cold cutoff low/trough and the intense low-level warm air advection by the South Atlantic subtropical high. Turbulent fluxes in the cyclone region are not above average during cyclogenesis, but the subtropical high flow advects great amounts of moisture from distant regions to fuel the convective activity. Although most of the SCs develop during austral summer (December-February), it is in autumn (March-May) that the most ''tropical'' environment is found (stronger surface fluxes and weaker vertical wind shear), leading to the most intense episodes.

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Section: Mean Characteristicsmentioning

confidence: 71%

Section: Sc Spatial Density and The Importance Of Rg1 Cyclogeneticmentioning

confidence: 92%

Subtropical Cyclones over the Southwestern South Atlantic: Climatological Aspects and Case Study

et al. 2014

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“…Mendes et al, 2010;Bitencourt et al, 2013), além do estudo sobre o papel dos fluxos de calor latente e sensível em superfície associados a ciclogênese explosiva (Piva, 2001e Piva et al, 2008 Hoskins (1985), Uccellini et al (1985), Wang e Rogers (2001), indicam a associação entre as variações da altura da tropopausa com a ocorrência de ciclogênese explosiva em superfície. Na literatura, como por exemplo em Santurette e Georgiev (2005), tem-se que a superfície de 1.5 PVU (potential vorticity unit) é representativa da tropopausa dinâmica, embora alguns trabalhos considerem o valor de 1.0 PVU (Bithell et al 1999) ou 2.0 PVU (Cau et al 2007), lembrando que no Hemisfério Sul valores negativos de vorticidade potencial representam vorticidade ciclônica.…”

Section: Introductionunclassified

Analysis of an explosive cyclogenesis case occurred in 03/01/2014 on the south of the Atlantic Ocean

Avila

Nunes

Alves

2016

Revista Brasileira De Geografia Física

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A região sul do Brasil está próxima de uma das regiões identificadas como ciclogenéticas com alta freqüência de ciclones extratropicais. Há um tipo de ciclone extratropical que é caracterizado por um aprofundamento muito rápido no campo de pressão a superfície, gerando um forte gradiente horizontal de pressão que produz grandes quantidades de precipitação, ventos muito fortes e ondas altas. Este tipo de ciclone é chamado de ciclone explosivo e normalmente se forma sobre o mar e atinge as cidades da costa leste que são densamente povoadas causando prejuízos consideráveis. É um fenômeno de difícil previsão devido a rapidez com que se forma e à escassez de dados observacionais sobre o mar. Este trabalho faz parte de um esforço no sentido de obter um maior conhecimento da sua estrutura dinâmica e termodinâmica. O ciclone estudado se formou a partir das 00Z do dia 03/01/2014 e apresentou uma queda de 42 hPa em 24 horas classificando-se como ciclogênese explosiva forte, o que é raro na região, e mais ainda no verão. A análise dos campos mostrou um desenvolvimento explosivo bem de acordo com a literatura no que se refere à anomalia da tropopausa dinâmica, com sua distribuição de vorticidade potencial, umidade relativa, movimentos verticais e tendência do Ozônio, enquanto os valores de calor latente e sensível foram surpreendentemente insignificantes. Pela região onde se iniciou, na confluência entre as correntes quente do Brasil e fria das Malvinas, o mecanismo que mais influenciou a formação foi a instabilidade baroclínica. Palavras-chave: vorticidade potencial, tropopausa dinâmica. Analysis of an explosive cyclogenesis case occurred in 03/01/2014 on the south of the Atlantic Ocean A B S T R A C TThe south region of Brazil is near one of the regions identified as ciclogenetic, with a high frequency of extratropical cyclones. There is a kind of extratropical cyclone characterized by a very rapid deepening in the field of surface pressure generating a strong horizontal pressure gradient producing great amounts of precipitation, strong winds and high waves. This type of cyclone is called explosive cyclone and usually forms on the sea surface attaining the densely populated cities of the east coast and causing considerably losses. It is a phenomenon of difficult prediction due to the rapid formation and the scarceness of observational data over the sea. This work is part of an effort to acquire a better knowledge of its dynamic and thermodynamic structure. The studied cyclone formed since 00Z of 01/03/2014 and presented a drop of 42 hPa in the following 24 hours classifying as strong explosive cyclogenesis, rare in that region and even more in the summer. The fields analysis showed an explosive development according well with the literature respecting the dynamic tropopause anomaly with its potential vorticity, relative humidity, vertical velocity and Ozone tendency distributions, while the values of latent and sensible heat were surprisingly insignificant. By the initial region

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“…The moisture transport via SALLJ is considerably lower and more moisture from the Atlantic is fed into the then active North American Monsoon System. A major influence on the weather in the southern part of SA is the formation and movement of extratropical cyclones, which during winter tend to be more frequent and of higher complexity (Mendes et al 2009). …”

Section: Application: Regional Climate Modeling Over South Americamentioning

confidence: 99%

“…5, right), the modeling of GEO500 by CCLM is slightly less accurate than in summer (still only 8 % of the STARS realizations perform better than the CCLM run). This might be attributed to a higher complexity of the extratropical cyclogenesis during winter (Mendes et al 2009) and its relatively greater influence on the South American climate due to the JJA northward displacement of general circulation patterns.…”

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confidence: 99%

Complex networks for climate model evaluation with application to statistical versus dynamical modeling of South American climate

et al. 2014

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In this study we introduce two new nodeweighted difference measures on complex networks as a tool for climate model evaluation. The approach facilitates the quantification of a model's ability to reproduce the spatial covariability structure of climatological time series. We apply our methodology to compare the performance of a statistical and a dynamical regional climate model simulating the South American climate, as represented by the variables 2 m temperature, precipitation, sea level pressure, and geopotential height field at 500 hPa. For each variable, networks are constructed from the model outputs and evaluated against a reference network, derived from the ERA-Interim reanalysis, which also drives the models. We compare two network characteristics, the (linear) adjacency structure and the (nonlinear) clustering structure, and relate our findings to conventional methods of model evaluation.To set a benchmark, we construct different types of random networks and compare them alongside the climate model networks. Our main findings are: (1) The linear network structure is better reproduced by the statistical model statistical analogue resampling scheme (STARS) in summer and winter for all variables except the geopotential height field, where the dynamical model CCLM prevails. (2) For the nonlinear comparison, the seasonal differences are more pronounced and CCLM performs almost as well as STARS in summer (except for sea level pressure), while STARS performs better in winter for all variables.

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Climatology of extratropical cyclones over the South American–southern oceans sector

Cited by 43 publications

References 34 publications

Subtropical Cyclones over the Southwestern South Atlantic: Climatological Aspects and Case Study

Subtropical Cyclones over the Southwestern South Atlantic: Climatological Aspects and Case Study

Analysis of an explosive cyclogenesis case occurred in 03/01/2014 on the south of the Atlantic Ocean

Complex networks for climate model evaluation with application to statistical versus dynamical modeling of South American climate

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