Distúrbios ondulatórios de leste (DOLs) na região do centro de lançamento de Alcântara-MA

Coutinho, Eliane de Castro; Fisch, Gilberto

doi:10.1590/s0102-77862007000200005

Cited by 30 publications

(14 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The dashed lines show the approximate trough axes. On day −2 d, at 1000 hPa (Figure 2 The study of [26] identified the layer with highest occurrence of EWDs throughout the entire year. Their results showed that the highest frequency of EWDs occurs in the 850-700 hPa layer during the rainy season, in accordance with the results presented here.…”

Section: Synoptic and Dynamic Analysis Of Ewdsmentioning

confidence: 99%

“…Several studies have shown that EWDs occur in various tropical regions, mainly in the western Pacific Ocean, Caribbean Sea, West Africa, and eastern Atlantic Ocean [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In the South Atlantic tropical region, near the Brazilian cost, EWDs can also occur, though less frequently than elsewhere [8,[26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis

Gomes

Ambrizzi

Herdies

et al. 2015

Advances in Meteorology

View full text Add to dashboard Cite

This paper aims to identify the circulation associated with Easterly Wave Disturbances (EWDs) that propagate toward the Eastern Northeast Brazil (ENEB) and their impact on the rainfall over ENEB during 2006 and 2007 rainy seasons (April–July). The EWDs identification and trajectory are analyzed using an automatic tracking technique (TracKH). The EWDs circulation patterns and their main features were obtained using the composite technique. To evaluate the TracKH efficiency, a validation was done by comparing the EWDs number tracked against observed cases obtained from an observational analysis. The mean characteristics of EWDs are 5.5-day period, propagation speed of ~9.5 m·s−1, and a 4500 km wavelength. A synoptic analysis shows that between days −2 d and 0 d, the low level winds presented cyclonic relative vorticity and convergence anomalies both in 2006 and 2007. The EWDs signals are strongest at low levels. The EWDs propagation is associated with relative humidity and precipitation positive anomalies and OLR and omega negative anomalies. The EWDs tracks are seen over all ENEB and their lysis occurs between the ENEB and marginally inside the continent. The tracking captured 71% of EWDs in all periods, indicating that an objective analysis is a promising method for EWDs detection.

show abstract

Section: Synoptic and Dynamic Analysis Of Ewdsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis

Gomes

Ambrizzi

Herdies

et al. 2015

Advances in Meteorology

View full text Add to dashboard Cite

show abstract

“…For example, when the ITCZ shifts to its southernmost position, it is responsible for increased rainfall totals in March and April (Uvo, ; Silva, ; Utida et al ., ). In the transition between the first and second halves of the year, easterly wave disturbances (EWD) formed in the atmospheric pressure field propagate westbound from the African continent until the eastern portion of South America, influencing rainfall rates over these capitals (Dunn, ; Yamazaki, ; Coutinho and Fisch, ). Furthermore, these cities are also influenced by sea‐breeze circulation, which transport clouds from the ocean to the land, and by cold fronts propagated throughout the coastline (Rotunno, ; Sousa et al ., ).…”

Section: Resultsmentioning

confidence: 99%

What is the return period of intense rainfall events in the capital cities of the northeast region of Brazil?

Oliveira

Lima

2019

Atmospheric Science Letters

View full text Add to dashboard Cite

The northeast of Brazil is characterized by a semiarid climate, in which there is a considerable temporal and spatial variability in the distribution of rainfall. In this region, the occurrence of intense rainfall events (IREs) causes severe damage to the population, given that the rampant urbanization and land use processes make cities more susceptible to harmful consequences. Thus, the objective of this study is to estimate the period and the level of return of IREs in the capital cities of the northeast Brazil. For that end, observed data from weather stations of the National Institute of Meteorology for the period from 1988 to 2017 were used. We defined thresholds based on the excesses above the mean and inserted the data in the generalized Pareto distribution in order to obtain diagnostics of future estimates. Results showed that return periods were surpassed in seven of the nine capital cities in 2018. Furthermore, the estimates for IREs with a return period of 5, 10, and 100 years were higher if compared to the return period of 1 year. The results found in this study are extremely relevant for the understanding of the occurrence of these events and also serve as a tool for decision-making and the elaboration of policies aimed at minimizing the impacts of such events. K E Y W O R D S extreme value theory, generalized Pareto distribution, natural disasters

show abstract

“…Diversos estudos sobre as características turbulentas do local já foram realizadas, quer seja por observações (Fisch, 1999e Roballo e Fisch, 2008, quer seja por ensaios em túnel de vento (Pires et al, 2009). Também já foram realizados estudos sobre a atuação de sistemas atmosféricos no local (Barbosa et al, 2006, Coutinho e Fisch, 2007.…”

Section: Materiais E Métodosunclassified

Escoamento atmosférico no Centro de Lançamento de Alcântara (CLA): parte II - ensaios no túnel de vento

Roballo

Fisch

Girardi

2009

Rev. bras. meteorol.

Self Cite

View full text Add to dashboard Cite

RESUMOEstudou-se o escoamento atmosférico no Centro de Lançamento de Alcântara (CLA), localizado junto a uma falésia de 50 m de altura, através de simulações em túnel de vento (TV) do CTA/ITA, na escala geométrica 1:1000, com a realização de quatro diferentes ensaios. No TV, os ensaios com degraus de 90° e de 70°, correspondentes à falésia, ambos sem e com simulação de rugosidade adicional a sotavento deles, mostraram: (i) perfeita simulação do perfil de vento oceânico (α = 0,15) sobre a posição do degrau representativo da falésia, utilizando pista de tapete, a montante, para prover a rugosidade necessária; (ii) número de Reynolds máximo possível com comprimento característico igual à altura do degrau neste TV foi 6,52.10 4 , enquanto no CLA é da ordem de 3.10 7 , razão pela qual é necessário um túnel mais potente; (iii) os expoentes mais próximos dos observados em Roballo e Fisch (2008) foram obtidos com um degrau reto, sem nenhum revestimento especial no piso normal do túnel, exceto o tapete a montante do degrau; (iv) a fixação de cubos a jusante do degrau para representar a vegetação resultou em rugosidades bem maiores que as observadas sobre a vegetação do CLA, possivelmente simulando situações urbanas ou industriais; (v) simulação das características típicas do escoamento após o degrau, tais como o descolamento, a formação de bolha de circulação e nova aderência; (vi) uso de TVs mais potentes certamente permitirá a simulação da situação atmosférica do CLA. Palavras chaves: falésia, número de Reynolds, Lei de Potência, perfil de velocidade. ABSTRACT: ATMOSPHERIC FLOW AT THE ALCANTARA LAUCHING CENTER (ALC): PART II-EXPERIMENTS AT A WIND TUNNEL.The atmospheric flow at the Alcantara Launching Center (ALC), which is localized near a 50 m cliff, was studied through analysis of wind tunnel (WT) experiments, using a 1:1000 geometric scale and floor level configurations to represent the cliff and its downwind roughness. The WT experiments, with 90° and 70° steps representing the cliff, both with and without additional downwind roughness, did show: (i) a perfect simulation of the ocean wind profile (a = 0.15) above the position of the step representing the cliff, through the use of a upwind carpeted fetch to provide the necessary roughness; (ii) the highest Reynolds number possible, based on the height of the cliff, was 6.52 x 10 4 inside this WT, while it reached 3 x10 7 at the ACL -thus, a more powerful tunnel is needed to simulate this last situation; (iii) the values of a nearest to the ones obtained at the ACL resulted from the 90° step experiment without any extra covering over the floor, except the upwind carpet; (iv) the fixing of cubes downwind of the step resulted roughness much greater than the ones observed over the ACL vegetation, so possibly simulating urban or industrial situations; (v) typical characteristics which occur downwind a step were simulated, such as the detachment and the posterior reattachment of the flow, plus the formation of circulation bubbles; (vi) the use of more powerful WTs would c...

show abstract

Distúrbios ondulatórios de leste (DOLs) na região do centro de lançamento de Alcântara-MA

Cited by 30 publications

References 4 publications

Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis

Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis

What is the return period of intense rainfall events in the capital cities of the northeast region of Brazil?

Escoamento atmosférico no Centro de Lançamento de Alcântara (CLA): parte II - ensaios no túnel de vento

Contact Info

Product

Resources

About