| Abstrakt: |
Wet‐bulb globe temperature (WBGT)—a standard measure for workplace heat stress regulation—incorporates the complex, nonlinear interaction among temperature, humidity, wind and radiation. This complexity requires WBGT to be calculated iteratively following the recommended approach developed by Liljegren and colleagues. The need for iteration has limited the wide application of Liljegren's approach, and stimulated various simplified WBGT approximations that do not require iteration but are potentially seriously biased. By carefully examining the self‐nonlinearities in Liljegren's model, we develop a zero‐iteration analytic approximation of WBGT while maintaining sufficient accuracy and the physical basis of the original model. The new approximation slightly deviates from Liljegren's full model—by less than 1°C in 99% cases over 93% of global land area. The annual mean and 75%–99% percentiles of WBGT are also well represented with biases within ±0.5 $\pm 0.5$°C globally. This approximation is clearly more accurate than other commonly used WBGT approximations. Physical intuition can be developed on the processes controlling WBGT variations from an energy balance perspective. This may provide a basis for applying WBGT to understanding the physical control of heat stress. Plain Language Summary: Wet‐bulb globe temperature (WBGT) is a standard way to measure heat stress in the workplace. It incorporates the complex, nonlinear interactive effects of temperature, humidity, wind and radiation. This complexity requires WBGT to be calculated iteratively which is computationally intensive and less straightforward to implement algorithmically. To address these issues, we came up with a simplified version of WBGT that obviates the need for iteration. This simplified approach is computationally straightforward and also highly accurate. Key Points: Accurate wet‐bulb globe temperature (WBGT) calculation, such as Liljegren's model, requires iterationBy examining self‐nonlinearities in Liljegren's model, we develop a simplified, analytic form—WBGTˆ $\widehat{WBGT}$—that does not require iterationWBGTˆ $\widehat{WBGT}$ is more accurate than commonly used simplified approximations, while retaining most of the physics in the Liljegren formulation [ABSTRACT FROM AUTHOR] |
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