Offering a model for estimating black globe temperature according to meteorological measurements
Somayeh Farhang Dehghan
Sayed Mohammad Jafari
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© 2017 Royal Meteorological Society Black globe temperature (T g ) is one of the most common measurement variables used for assessing heat stress; however, it is usually not reported in meteorological data. This study developed a model to estimate T g based on meteorological measurements, in order to calculate the occupational heat stress index in outdoor workplaces. This descriptive and analytical study was conducted from May to September 2013 in Qom, Iran. Environmental variables such as natural wet-bulb temperature (T nw ), dry-bulb temperature (T a ), solar radiation (SR) and relative humidity (RH) were measured by meteorological instruments in weather stations and T g was measured by a globe thermometer in the same situations at different times. Data were analysed using IBM SPSS16. Independent variables including T nw , T a , SR and RH and the dependent variable T g were introduced to the software, and several regression models were obtained. Finally, a model that had the most appropriate correlation with a significance level of 0.05 was chosen as the best model. The correlation co-efficients between T g and T nw , T a , SR and RH were obtained as 0.84, 0.63, 0.75 and −0.75, respectively. The results showed that T a , SR and RH can justify about 90% of the variation in T g . There was a significant relationship between T g and T a , SR and RH (p < 0.05). The correlation co-efficient between actual and estimated data was 0.95 (p < 0.001). The model obtained can be trusted to estimate the black globe temperature in a hot and dry environment and can be useful in assessing occupational heat stress in outdoor workplaces.