A Preliminary Study of Summertime Tropospheric Circulation Patterns over South America Estimated from Cloud Winds

Virji, Hassan

doi:10.1175/1520-0493(1981)109<0599:apsost>2.0.co;2

Cited by 211 publications

(148 citation statements)

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“…3a;Virji 1981;Lenters and Cook 1995;Wang and Paegle 1996;Zhou and Lau 1998;Vera et al 2006a, b). Trade winds enter the continent at low latitudes from the tropical Atlantic Ocean, that are channeled southward by the Andes reaching subtropical latitudes.…”

Section: Observed and Remo Circulationmentioning

confidence: 94%

A high-resolution 43-year atmospheric hindcast for South America generated with the MPI regional model

Silvestri

Vera

Jacob³

et al. 2008

Clim Dyn

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An evaluation of the present-day climate in South America simulated by the MPI atmospheric limited area model, REMO, is made. The model dataset was generated by dynamical downscaling from the ECMWF-ERA40 reanalysis and compared to in-situ observations. The model is able to reproduce the low-level summer monsoon circulation but it has some deficiencies in representing the South American Low-Level Jet structure. At upper levels, summer circulation features like the Bolivian High and the associated subtropical jet are well simulated by the model. Sea-level pressure fields are in general well represented by REMO. The model exhibits reasonable skill in representing the general features of the mean seasonal cycle of precipitation. Nevertheless, there is a systematic overestimation of precipitation in both tropical and subtropical regions. Differences between observed and modeled temperature are smaller than 1.5°C over most of the continent, excepting during spring when those differences are quite large. Results also show that the dynamical downscaling performed using REMO introduces some enhancement of the global reanalysis especially in temperature at the tropical regions during the warm season and in precipitation in both the subtropics and extratropics. It is then concluded that REMO can be a useful tool for regional downscaling of global simulations of present and future climates.

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Section: Observed and Remo Circulationmentioning

confidence: 94%

A high-resolution 43-year atmospheric hindcast for South America generated with the MPI regional model

Silvestri

Vera

Jacob³

et al. 2008

Clim Dyn

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“…Como consequência dessa circulação anticiclone, uma região de baixa pressão é formada nos baixos níveis da atmosfera, e a convergência de ar ocorre (Virji, 1981), causando o período de seca no Centro-Oeste (Kousky e Kayano, 1994). Além disso, há ondas de frio provocadas por surtos de ar polar durante o inverno (maio-agosto) com baixas temperaturas em latitudes médias, que afetam o sul do Brasil, com o arrefecimento considerável no centro e no norte da Amazônia (Parmenter, 1976;Marengo et al, 1997).…”

Section: Descrição Da Climatologia Regionalunclassified

Sazonalidade do Balanço de Energia e Evapotranspiração em Área Arbustiva Alagável no Pantanal Mato-Grossense

Machado

Biudes

Angelini

et al. 2016

Rev. bras. meteorol.

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ResumoO Pantanal apresenta períodos de inundação que modelam a paisagem e atuam como filtro ao estabelecimento e desenvolvimento de plantas. Perturbações antrópicas ou naturais podem alterar a distribuição da energia disponível no ecossistema. Diante da necessidade de compreensão da variabilidade temporal do balanço de energia em paisagens naturais inundáveis, o objetivo deste estudo foi analisar a sazonalidade do balanço de energia em área arbustiva alagável composta por Combretum lanceolatum Pohl no Pantanal Mato-grossense. As estimativas do fluxo de calor latente (LE) e sensível (H), e da evapotranspiração (ET) foram obtidas pelo método da razão de Bowen entre maio de 2012 e abril de 2013. A energia disponível foi destinada prioritariamente ao LE (64,1%), seguido ao H (35,8%) e quase zero ao fluxo de calor no solo (0,1%). Os componentes do balanço de energia apresentaram forte sazonalidade, com maior LE durante a estação chuvosa e maior H durante a estação seca. A evapotranspiração foi menor durante a estação seca devido ao baixo conteúdo de água no solo e transpiração da vegetação dominante na área de estudo. Os resultados obtidos nesse trabalho sugerem que o ambiente estudado é limitado pela disponibilidade de energia e água. Palavras chave: distribuição de energia, microclima, Combretum lanceolatum, áreas úmidas. Seasonality of Energy Balance and Evapotranspiration in a FloodedScrubland in the Pantanal of Mato Grosso AbstractThe Pantanal has flood periods that model the landscape and act as a filter to the establishment and development of plants Anthropogenic or natural disturbances can alter the available energy distribution in the ecosystem. Due to the need of understanding the temporal variability of the energy balance in flood natural landscapes, the objective of this study was to analyze the seasonality of the energy balance in flooded shrub area consisting of Combretum lanceolatum Pohl in Mato Grosso Pantanal. The estimates of latent (LE) and sensible (H) heat flux, and evapotranspiration (ET) were obtained by the method of Bowen ratio between May 2012 and April 2013.The available energy was intended primarily to LE (64.1%), followed by H (35.8%) and almost zero to heat flow in soil (0.1%). The components of the energy balance showed strong seasonality, with highest LE in the wet season and highest H in the dry season. The evapotranspiration was lower during the dry season due to the lower soil water content and transpiration of dominant vegetation in the study area. Results suggest that the study area was limited by the availability of energy and water.

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“…At low latitudes, there is an easterly flow from the tropical ocean, which after reaching the proximity of the Andes turns south transporting heat and moisture to the subtropics. Virgi (1981) using satellite data described this flow that has been amply confirmed afterward, even with different data sets (Zhou and Lau 1998). South of 40 S, a predominant westerly low-level flow persists throughout the year, accompanied by the typical mid-latitude perturbations.…”

Section: Climatic Aspects Related To Ssa Surface Temperaturementioning

confidence: 99%

Relationship between Temperature and Circulation in Southeastern South America and its Influence from El Nino and La Nina Events.

Barros

Grimm

Doyle

2002

Journal of the Meteorological Society of Japan

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This paper explores the relationship between regional circulation anomalies and the interannual variability of surface temperature in Southern South America, east of the Andes (SSA). Two sets of monthly surface temperature for the 1963-1990 period were used; one was taken from the NCEP/ NCAR reanalysis, and the other was built from the synoptic network records. Although these sets present some differences between them, the conclusions found are independent of the data set.Monthly and seasonal indices were developed to explore, through linear correlation, the connection between interannual temperature variability in SSA and some features of regional circulation. The intensification (reduction) of the west component of the wind at the upper troposphere over the subtropical latitudes of South America, and the northward (southward) shift of the maximum westerly wind over SSA tend to be associated with cold (warm) anomalies of surface temperature during practically every month throughout the year. At low levels, the enhancement (reduction) of the zonal geopotential gradient between the South Atlantic high and the Chaco low, representative of the northern component of the low-level flow, is generally associated with warm (cold) surface temperature anomalies.In SSA, monthly precipitation is positively correlated with the northern component of the geostrophic flow. Therefore the advection of temperature offsets the possible influence of precipitation, caused by the associated evaporation and cloudiness, on surface temperature. Hence, there are positive correlations between precipitation and temperature except for central Argentina in summer, and for southern Brazil in certain months. The fact that increased (decreased) precipitation accompanies enhanced (less) warm advection, contributes to moderate the interannual variability of surface temperature.The partial balance between the effects of warm advection and precipitation on surface temperature variability explains why, though ENSO phases have a considerable impact on precipitation and some influence on the regional circulation, their signals in the surface temperature are relatively modest. The exception is in JJA (0) in western SSA, for the most part a region with very scant precipitation during the austral winter, where the surface temperature anomalies are positive in El Niñ o, and negative in La Niñ a. The maximum anomalies coincide approximately with an enhancement (reduction) of the northern component of the flow, and of the warm advection at low levels in El Niñ o (La Niñ a) events.

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A Preliminary Study of Summertime Tropospheric Circulation Patterns over South America Estimated from Cloud Winds

Cited by 211 publications

References 0 publications

A high-resolution 43-year atmospheric hindcast for South America generated with the MPI regional model

A high-resolution 43-year atmospheric hindcast for South America generated with the MPI regional model

Sazonalidade do Balanço de Energia e Evapotranspiração em Área Arbustiva Alagável no Pantanal Mato-Grossense

Relationship between Temperature and Circulation in Southeastern South America and its Influence from El Nino and La Nina Events.

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