Converting Airport Data To Playing Field Heat Stress Information

Here’s how the <Airport RH-to-WBGT> calculator’s calculation of WBGT, based on weather data from a nearby airport, was worked out:

1.  A weather-hardened QuesTemp-15 heat stress monitor with logging capability (Quest Technologies, Oconomowoc, WI) was placed on a concrete surface about one meter from a tennis court in Tulsa, OK.

2.  This device recorded WBGT every 30 seconds from July 4 to Sept 11, 1998, and from May 1 to July 4, 1999.

3.  These WBGT values were compared with simultaneous hourly Dry Bulb Temperature and Wet Bulb Temperature data from Tulsa International Airport.

4.  The airport Dry Bulb Temperature and Wet Bulb Temperature were converted to a Discomfort Index (DI) using the formula DI = ((Dry Bulb Temp + Wet Bulb Temp)/2).

5.  Average airport DI values were subtracted from average tennis court WBGT's with the following results in °F (Daylight Saving Time):  7am, +0.1; 8am, +1.6; 9am, +3.1; 10am, +3.6; 11am, +3.9; 12pm, +3.9; 1pm, +4.0; 2pm, +3.5; 3pm, +3.3; 4pm, +3.2; 5pm, +2.9; 6pm, +2.7; 7pm, +1.4.

6.  Similar data sets made up of airport readings on playing field WBGT’s were obtained (for model validation purposes) from the following places: Aug 31-Sept 11, 1998 in New York City, NY (US Open Tennis Championships, LaGuardia Airport); July 11-17, 1999,  in Blaine, MN (Schwann USA Cup Soccer, Minneapolis-St Paul International Airport); and August 8-15, 1999, in San Antonio, TX (USTA Boys' 14's Tennis Championships, San Antonio International Airport).

7.  These “validation data” confirmed the accuracy of the method. Estimated  vs. measured WBGT's for the 3 test events (355 test hours) gave the following results: Range of WBGT's: 51-92°F. Mean error = 0.3°F. Standard error = 2.7°F. Estimated WBGT = 0.9945 x Measured WBGT.  R = 0.93.