Consistency assessment between summer simmer index and other heat stress indices (WBGT and Humidex) in Iran's climates

This study aimed to assess the applicability of summer simmer index (SSI) in different climates of Iran and compare it with other common heat stress indices including WBGT and Humidex. The daily mean air temperature and relative humidity were obtained from the Meteorological Organization of Iran for the 60-year period between 1957 and 2016. Statistical tests including Pearson correlation coefficient and linear regression tests were used to consistency assessment between Summer Simmer Index and wet-bulb globe temperature (WBGT) and Humidex indices. The results of the present study showed that the SSI is significantly correlated with both WBGT and Humidex indices (R-2 > 0.932, p < 0.001). In addition, the obtained correlation between SSI and Humidex was higher than correlation between SSI and WBGT in all the climates. Moreover, SSI in the Mediterranean region shows less correlation with both WBGT and Humidex indices (R-2 = 0.932 and 0.964 for WBGT and Humidex, respectively). The highly correlation coefficients were observed between SSI and WBGT and Humidex indices, and also between SSI and other environmental parameters; moreover interpreting of SSI is easy, so it can be suggested that SSI can be used as an alternative index for WBGT or Humidex in assessment of heat stress in different climates of Iran.

Automated summary

The study found that the Summer Simmer Index (SSI) is significantly correlated with the wet-bulb globe temperature (WBGT) and Humidex indices, with a higher correlation observed between SSI and Humidex. In the Mediterranean region, SSI showed less correlation with both WBGT and Humidex indices.