Association of Agrometeorologists

The discomfort levels in Gujarat-A comparison of different thermal stress indices


The characterization of discomfort of any location is essentially required to understand the efficiency of human activities. In the present study, four different thermal stress indices (Heat Index of Rothfusz (US_HI), simple Heat Index (S_HI), Discomfort index of Thom (EU_DI) and Discomfort index of South Africa (SA_DI) weather service) have been used to characterize the Gujarat state under different comfort level using daily climatic data of 12 stations spread across the state. Results revealed that all the thermal indices showed similar pattern of variation during the year, except the Heat Index of Rothfusz (US_HI) which is more or less constant during winter season when its values are less than 80. On an average, about 225 to 275 days have been characterized as the discomfort period of varying stress condition in different parts of the state. The peak period of discomfort index was found to be during May and June. Arnej and Viramagan are the two stations having highest level of discomfort at danger level. A comparison of all the four indices revealed that the two indices viz. US_HI and SA_DI are more or less similar in characterization; however, these indices are unable to detect and/or characterize the lower levels of discomfort. The Simple model (S_HI) could not differentiate the most discomfort period/location as characterized by the other three thermal indices. The thermal indices EU_DI seems to be very sensitive for discomfort as all 365 days at Surat has been characterized as discomfort to be experienced by the people.

Temperature humidity index (THI), apparent temperature (AT), discomfort index (DI), heat index (HI), distress index, wind chill, thermal comfort index