NWC REU 2018
May 21 - July 31



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Analysis of wet-bulb globe temperature calculations using in-situ observations

Tim Corrie III


What is already known:

  • Wet Bulb Globe Temperature (WBGT) is a measure of heat injury risk, and can be measured directly, but is expensive
  • WBGT is estimated by air temperature, natural wet bulb temperature, and black globe temperature
  • Mesonet approximates natural wet bulb temperature and black globe temperature using algorithms developed by Tulsa WFO
  • Eglin uses their own formulas to estimate WBGT but were developed in Florida and have not been verified in drier climates such as that of Oklahoma

What this study adds:

  • WBGT calculated by the Mesonet (by estimating ISO parameters) underestimates the instrument's WBGT by 3.3°F on average
  • WBGT calculated by each of the three Eglin equations overestimates the instrument's WBGT, and this overestimation increases as WBGT increases


Using the Wet-Bulb Globe Temperature (WBGT) to measure heat injury risk is paramount; however, with- out affordable instruments, the public has to rely on formulas. These formulas either overestimate WBGT (bad for production) or worse, underestimate WBGT (bad for humans, heat injury risk increases significantly and unnecessarily). Data were collected from 16 June 2018 through 16 July 2018 from the QUESTemp°34 (Q34) and synchronous data from the Oklahoma Mesonet, and WBGT index values were compared from Q34’s calculations, Mesonet calculation using approximations of natural wet bulb temperature and black globe tem- perature, and three equations utilized by Eglin Air Force Base. With roughly 2.5 weeks of valid, filtered data, it was determined that the Mesonet calculations underestimate the instruments’, and all three of Eglins cal- culations overestimate the instruments’. Future work includes examining the algorithms created by the Tulsa Weather Forecast Office to calculate the Mesonet WBGT and comparing the WBGT to the Environmental Stress Index.

Full Paper [PDF]