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Estimating Black Globe Temperature Based on Meteorological Data

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Livestock Environment VIII, 31 August – 4 September 2008, Iguassu Falls, Brazil  701P0408.(doi:10.13031/2013.25593)
Authors:   S. H. N Turco, T. G. F da Silva, G M de Oliveira, M. M. V. B. R Leitão, M. S. B de Moura, C Pinheiro, C. V da Silva Padilha
Keywords:   Animal comfort index, Bioclimatic index, Temperature model

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.

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