value would have the opposite effect. Te major energy streams are convective heat loss (C), evaporative heat loss (E), conductive heat loss (K), radiative exchange (R), and metabolic heat production (M) (Kenny et al, 2009). Te estimated physiological thermal stress, also called energy budget value, can be measured as watt per square meter of a person’s surface area (W/m2
), a unit of energy density.
Te measured microclimate and the athlete’s surveyed exertion level were the main inputs to the COMFA model estimation. Te metabolic rate of a running person ranged between 300 – 650 W/m2
depending on exertion level,
and the summer uniform was selected to determine the clothing insulation level.
Results Microclimate condition
Surface temperature showed a significant difference between NT and AT. Te differences in microclimate between the two field types are summarized in Table 2. Regarding the overall pattern, all the measurement values of AT’s microclimate (e.g., air temperature, solar radiation, relative humidity, and wind speed) were slightly higher than NT. However, except for surface temperature, the degree of their difference is not significant considering their error ranges of measurement. In contrast, the surface temperature presented a large deviation between AT and NT, whose average difference was over 70.0 degrees F (21.11 C).
Table 2) AT – NT difference in microclimate conditions
*Standard deviation (Sd) *Difference (Diff.) Variable
Mean Diff. in Air temperature (°F) 33.12
Diff. in Solar radiation (W/ m2
)
Diff. in Relative humidity (%)
Diff. in Wind speed (mph)
Diff. in Surface temperature (°F)
16.58 2.97 1.67 70.15 Sd 0.38 35.76 0.95 1.40 14.39 Min 32.57 -29.54 1.33 -1.57 46.88 Max 33.90 74.76 4.38 4.56 96.50
Te daytime pattern of AT and NT surface temperature was further explored to identify the difference in variation over the day (Figure 2). AT’s surface temperature showed considerable fluctuation over time compared to NT’s. Over the four-days of measurements, the surface temperature ranged between 104.6 degrees F (40.33 degrees C) and 161.6 degrees F (72 degrees C) for AT and between 86.8 degrees F (30.44 degrees C) and 102.6 degrees F (39.22 degrees C) for NT. It seems that their daytime mean surface temperature was primarily affected by cloud cover. Overall, the surface temperatures peaked on September 7 when the cloud cover was at the lowest at 10 percent. Meanwhile, surface temperatures were lowest on September 22 when the cloud cover was relatively higher at 40 percent, with a somewhat cooler ambient temperature.
Te AT – NT difference in surface temperature showed similar daytime patterns with the mean surface temperature. Teir difference reached a peak of 96.5 degrees F (35.83 degrees C) at 2:30 PM CST, September 7, and lowest at 46.8 degrees F (8.22 degrees C) on 3:30 PM CST, September 22. Te degree of temperature gap was likely due to increase from morning to high solar noontime at around 1:00 PM CST and after then declining toward evening time at 4:00 PM CST. As surface temperature was the microclimate component primarily determined by field characteristics, we expected it to be a crucial driver causing differences in players’ thermal stress.
16
TPI Turf News September/October 2022
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