Estimation of thermal comfort felt by human exposed to extreme heat wave in a complex urban area using a WRF-MENEX model.

Thermal comfort could indicate human thermal sensation when exposed to a local meteorological condition. Because humans can suffer illness when exposed to heat or even die, it is essential to assess human comfort levels to increased temperature and to provide this information to the public. This study aims to estimate thermal comfort using the human heat balance model combined with a numerical meteorological model in Seoul mega city during the heat wave periods experienced during 2016. The gridded thermal comfort index of physiological subjective temperature (PST) was calculated based on the Man-Environment Heat Exchange (MENEX) model, which used as inputs the meteorological parameters, clothing insulations, and metabolic rates. High-resolution meteorological parameters were obtained by coupling Weather Research and Forecasting (WRF) model with Building Effect Parameterization (BEP) + Building Energy Model (BEM) using detailed urban classification. The modeling results showed that the PST distribution has a clearly heterogeneous spatial distribution during the heat wave period. The high PST values were largely found in the residential area during the day, due to the high temperature and low wind speed associated with high-density buildings, and the daily maximum PST reached a very hot level (44.1-54.0 °C). Our study suggested that the human heat balance model combined with the numerical meteorological model could be used to provide more reliable information about thermal comfort to groups that may be vulnerable to the effects of heat waves in complex urban environments.