Mário de Miranda Vilas Boas Ramos Leitão

Avaliação do desempenho de diferentes métodos de estimativa da evaporação para duas regiões da Paraíba

As regioes do Cariri e Sertao da Paraiba, nas cidades de Boqueirao e Patos, no periodo de 1 de abril de 2002 a 28 de fevereiro de 2003, foram estudadas com o objetivo de se avaliar o desempenho de diferentes metodos e obter-se as melhores estimativas da evaporacao para essas regioes; para tanto, usaram-se medidas diarias de evaporacao do tanque evaporimetrico padrao de 20 m2 (WMO, 1996). Os metodos avaliados foram: Penman (1948); balanco de energia - razao de Bowen; Linacre (1993); Snyder (1992); Kohler et al. (1955); Gangopadhyaya et al. (1966) e Hounam (1973). Os resultados indicaram que os metodos de estimativa de evaporacao que utilizam a umidade relativa do ar, velocidade do vento e radiacao solar, apresentaram os melhores desempenhos. O metodo proposto por Snyder (1992) teve o melhor desempenho nas duas regioes estudadas, com erros relativos de -4,2% para Boqueirao e -3,3% para Patos. O metodo de Linacre (1993), que utiliza os valores extremos de temperatura diaria do ar, apesar de ter apresentado os maiores erros relativos -16,9% em Boqueirao e -18,2% em Patos, mostrou que, se for corretamente calibrado, pode ter desempenho satisfatorio para as duas areas estudadas.

Characterization of human thermal comfort in urban areas of brazilian semiarid

Experimental studies were conducted aiming to characterize the thermal conditions in urban areas of the Brazilian semiarid for identifying the level of human thermal comfort in urban areas of the municipalities of Mossoro-RN, Serra Talhada-PE, Petrolina-PE and Juazeiro-BA. The results showed that the constituent elements of urban areas contribute to human thermal discomfort index (DIT). Both the wet and dry seasons showed up an uncomfortable condition in Mossoro on May 15th and on 23rd, 2008 (rural area) and on May 25rd, 2008 (urban area). By applying Thoms equation for obtaining the DIT, it was observed that the urban areas reported thermal comfort conditions always inferior to those observed in the rural areas. The results indicate conditions of partial comfort for the all areas surveyed. However, the incidence of human thermal discomfort related to the minimum, average and maximum air temperatures are, probably associated to the formation of urban heat islands. In addition, the afforestation is an effective mechanism of mitigating the adverse effects of these structures with better quality of life to the population. Therefore, it can be stated that the Brazilian semiarid region has specific urban climate, which is influenced by the design characteristics of the urban structure and buildings.

Coeficiente de cultura e produtividade da cebola submetida a diferentes lâminas de irrigação

The present study aimed to determine crop coefficients and evaluate the productivity of onion under different irrigation levels. The experiment was conducted in the experimental field at DTCS/UNEB Juazeiro during the period from April to September 2011. For determining the ETc, daily measurements were made in evapotranspirometers. The ETo was obtained by the methods of the Class A pan (TCA) and Penman-Monteith (PM) and the Kc by: Kc = ETc/ETo. The experimental design was completely randomized with three treatments and seven replications. The examined variables were: transverse diameter, mean bulb weight, total production, commercial production, total soluble solids and titratable acidity. The Kc values found by taking as a basis the ETo determined by the TCA method with the Kp calculated using weather data obtained in situ, were very close to those determined by the PM method; the total productivity surpassed the national average by 122% for T1 (irrigation on the basis of ETc) and T3 (irrigation on the basis of ETo calculated according to PM) treatments and 86% for the T2 (irrigation on the basis of ETo calculated according to TCA) treatment; the irrigation management, based on the TCA method can provide high productivity, taking into account local climatic conditions.

Conforto e estresse térmico em ovinos no Norte da Bahia

The climate is a determining factor for the success of the productive activity, thus for greater efficiency on the farm, the animals x environment interaction should be considered because they show different responses to the peculiarities of the climate of each region. This study aimed to evaluate the thermal comfort of the Santa Ines, Dorper and undefined breed - SRD sheep, created under open sky conditions. The research was conducted at the Campus III of the University of the State of Bahia in Juazeiro, during the period November 15, 2009 to February 14, 2010. The animals were divided into four groups according to coat color: white, light brown, dark brown and black. For measurements of microclimatic conditions faced by sheep, an automatic meteorological station was installed in the experimental area, with its sensors positioned at the mean height of the animal, 50 cm above the surface. The results showed that due to high radiant heat load, resulting in a high incidence of solar radiation and high temperatures, the animals regardless of breed and coat color experienced, mainly in the afternoon, high thermal stress and discomfort.

Estimating black globe temperature based on meteorological data.

An automatic weather station, comprising of temperature and humidity sensors, a pyranometer, an anemometer, and a thermocouple inside a black globe, was installed in a grassed area at the University of the State of Bahia - UNEB, Juazeiro County, Bahia State, Brazil. Half of the data collected at this station was used to generate models (simple or multiplicative) for estimating the Black Globe Temperature (BGT). Model performance was evaluated by using the second half of the data. Statistical precision and accuracy indices and statistical errors were used to analyze the collected data and the Student`s t test was used to evaluate the significance of the model parameters. Two models to estimate the BGT using meteorological variables were obtained: BGTd = [1.360 Tair d - 2.358]·[0.075 ln(Rs) - 0.562] and BGTn = [0.942 Tair n]. One model was elaborated for daytime BGTd), when the air temperature (Tair d) and solar radiation (Rs) were combined to generate a multiplicative model (R2 = 0.877), and a second model was developed to determine the BGT values for night-time (BGTn) based on the night-time air temperature (Tair n) (R2 = 0.962). The models developed resulted in great performance to predict the black globe temperature, allowing the estimation of bioclimatic indices to assess the conditions of the environment, to accomplish regional studies, and to indicate best house designs for animals.

Thermal Comfort Level Assessment in Urban Area of Petrolina-PE County, Brazil

This study evaluated the thermal conditions of urban areas in Petrolina-PE, from continuous data collected in urban and rural areas for the year of 2012. The results characterized urban heat islands (UHI) with varying intensity in urban areas, especially UHI = 5.3 °C (high intensity) occurred on April 28, 2012. It was evident that the constituent elements of urban areas contribute to the formation and expansion of UHI bringing thermal discomfort for its inhabitants. An adaptation to Thom’s equation for calculating the Thermal Discomfort Index (DIT), was used to obtain the maximum (DITx) and minimum (DITm) thermal discomfort. In the urban area, the DITm indicated thermal comfort in 23.0% of the days and partial comfort in 77.0% of days surveyed. Already, the DITx characterized 71.6% of days with partial comfort and 28.4% of days with thermal discomfort. In the rural area, The DITm indicated that 41.5% of days were thermally comfortable and 58.5% of days had partial comfort. However, the DITx pointed 87.7% of the days of this environment with partial thermal comfort and 12.3% of thermally uncomfortable days. Finally, the results showed that afforestation of urban area constitutes to an effective and efficient way to mitigate thermal discomfort.

Influence of Plastic Covering on the Microclimate in Vineyards in the São Francisco River Valley Region

Abstract Data from field experiments conducted in table grape vineyards variety of Festival in Petrolina-PE in the period fromSeptember 19 to October 12, 2010 were used to evaluate the influence of plastic cover on microclimate conditions ofvineyards in Sao Francisco River Valley region. Three treatments were studied: canopies without plastic cover (WC);with plastic cover positioned at 50 cm (PC50), and at 100 cm (PC100) above canopy. The results indicate that the plasticcover prevented the passage of about 40% of the global and net radiation, retained the relative humidity inside the can-opy, generated an increase of air temperature and marked reduction in wind speed over the canopy of treatment PC50.However, treatment PC100 had a higher incidence of short wavelength and net radiation under canopy (on the berries)than WC and PC50 treatments, resulting in more favorable weather conditions, providing about 40% greater productiv-ityinthistreatment.Therefore,thevineyardwithplasticcoverplacedat100cmabovecanopyrepresentsamoresuitablealternative to the climatic conditions of the region of the Sao Francisco River Valley.