Análise de um Vórtice Ciclônico e Mesoescala Associado a ZCAS em Janeiro de 2009

Abstract

Resumo Este trabalho objetiva analisar a condição termodinâmica durante a atuação de um vórtice ciclônico de mesoescala (VCM) embebido na Zona de Convergência do Atlântico Sul (ZCAS), no mês de janeiro de 2009. Os VCMs possuem características similares: encontram-se na baixa e média troposfera associado a altos índices pluviométricos, ciclo de vida inferior a 24 h, escala espacial de aproximadamente 200 km2 e o descolamento do sistema na mesma direção do fluxo predominante na baixa troposfera. Além disso, há uma relação direta entre estes máximos pluviométricos e a circulação ciclônica dos vórtices. O VCM simulado através do modelo de mesoescala BRAMS se formou no Estado de Mato Grosso e esteve associada à ocorrência de chuvas intensas. Além das características típicas de caracterização, este sistema também apresentou vorticidade relativa da mesma ordem de magnitude do parâmetro de Coriolis (10−4 s−1), núcleo quente acima do nível de máxima intensidade e um rápido crescimento do centro de vorticidade ciclônica principalmente nos baixos níveis. Pela comparação da chuva simulada com o produto Hidroestimador, sugere-se que o modelo BRAMS, com uma alta resolução espacial e temporal, melhora a representação do VCM, comparado com os dados da reanálise CFSR do NCEP.

Synoptic analysis of an intense rainfall event in Paraíba do Sul river basin in southeast Brazil

“…Over the study region the 8 day mean value of the low level moisture convergence is about 3 × 10 −5 g kg −1 s −1 , which is three times greater than the value estimated by the product of normal values of specific humidity (10 g kg −1 ) and divergence (10 −6 s −1 ). One more important feature at low levels is a dipole blocking pattern (Rex, 1950) in the streamlines (Figure 4(a)), with an anticyclonic centre south of Uruguay (37 ∘ S, 56 ∘ W) and a cyclonic centre near the southern coast of Brazil (31 ∘ S, 45 ∘ W), as also observed by Dias Pinto et al (2013), Gozzo et al (2014) and Quadro et al (2016) in their respective case studies. In the mid-troposphere (Figure 4(b)), besides the dipole blocking pattern near the southern coast of Brazil, a confluent stream is observed between the western edge of the SASH and the cyclonic vortex over the continent, with high values of equivalent potential temperature (Θe, shaded) over the study region.…”

“…As will be shown in detail, the most prominent feature of this case study was the formation of a cyclone on the south/southeastern coast of Brazil, here called the cyclonic vortex embedded in the SACZ (CVES). Quadro et al (2016) analysed the thermodynamic conditions during the development of a mesoscale cyclonic vortex (MCV) embedded in the SACZ in January 2009 through numerical simulations with the Brazilian Regional Atmospheric Modelling System. According to those authors, MCVs are generated within a stratified environment in the SACZ region, drawing moisture from the environment and accelerating vertical motion and consequently causing intense rainfall.…”

Mesoscale Cyclonic Vortices Embedded in the South Atlantic Convergence Zone Associated with Natural Disasters in the State of São Paulo, Brazil

“…A MCV in the stratiform region of an MSC is characterized by having a hot core, where rising warm air induces convergence at low levels and further contributes to the amplification of the cyclonic vorticity. (Bosart & Sanders 1981;Chen et al 1998;Davis et al 2004;Quadro, Silva Dias & Herdies 2016).…”

Climate Indicators for a Watershed in the Eastern Amazon

“…Other factors that have an effect on precipitation and mean air temperature are the meso-and large-scale weather systems, since they contribute to the weather and climate variations in the Amazon region. Such weather systems include the Intertropical Convergence Zone (ITCZ) (HASTENRATH, 1991;REBOITA et al, 2010;FERREIRA et al, 2015), the South Atlantic Convergence Zone (SACZ) (CARVALHO et al, 2004;LOPES et al, 2013;QUADRO et al, 2016), and the El Niño-Southern Oscillation (ENSO) (GRIMM, 2011;LI et al, 2011;ANDREOLI et al, 2016;PEREIRA et al, 2017). ENSO, an ocean-atmosphere coupling phenomenon, is a major cause of climate variability, affecting global atmospheric circulation, and it has a significant influence on precipitation and air temperature variation throughout the planet.…”