Modeling the Wet Bulb Globe Temperature Using Standard Meteorological Measurements

Abstract

The U.S. Army has a need for continuous, accurate estimates of the wet bulb globe temperature to protect soldiers and civilian workers from heat-related injuries, including those involved in the storage and destruction of aging chemical munitions at depots across the United States. At these depots, workers must don protective clothing that increases their risk of heat-related injury. Because of the difficulty in making continuous, accurate measurements of wet bulb globe temperature outdoors, the authors have developed a model of the wet bulb globe temperature that relies only on standard meteorological data available at each storage depot for input. The model is composed of separate submodels of the natural wet bulb and globe temperatures that are based on fundamental principles of heat and mass transfer, has no site-dependent parameters, and achieves an accuracy of better than 1°C based on comparisons with wet bulb globe temperature measurements at all depots.

Keywords:

• environmental measurements
• heat indexes
• heat stress

ACKNOWLEDGMENTS

The authors are grateful to Michael Myirski for insightful comments and suggestions on an early version of the manuscript. This work was sponsored by the U.S. Army Chemical Materials Agency, Chemical Stockpile Emergency Preparedness Program, under Contract MIPR 7D22 CM7007 Amend 01 Rev 12.

Notes

^A If wearing nuclear-biological-chemical (NBC) clothing (mission-oriented protective posture (MOPP) level 4), add 5.6°C to WBGT index for easy work and 11.1°C to WBGT index for moderate and hard work.

^A Relative humidity and barometric pressure obtained from 5-m level of Tower 1 and 1 km away (same elevation and ground cover).

^A Percentage of cases where the magnitude of the difference between predicted and measured WBGT exceeded 1°C.

^B Solar irradiance measurements corrected for ∼ 20% calibration error.

^C No 2-m wind speed data available; 2-m wind speeds estimated using 10-m wind speeds.