Evaluation of the Spatial Distribution of Some Thermal Comfort Indices in Iraq using RayMan Model

Abstract

This work analyzes the spatial distribution of outdoor human thermal comfort in Iraq using Physiologically Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI). Monthly meteorological data from 38 stations (1981–2024) were downloaded from the NASA POWER database and calculated using the RayMan model for PET and UTCI. Then, monthly/seasonal/annual comfort maps were obtained through GIS-based kriging interpolation. The results represent a remarkably seasonal pattern: in winter situation are characterized by levels of blank mild to moderate cold stress and the greatest cold impact covers northern and Alpine territory, while summer conditions point towards strong to very strong heat stress, particularly on southern and south-eastern provinces. Spring and fall yielded the most comfortable results overall with many places at neutral to low-stress levels in April or October. The spatial patterns of PET and UTCI are in good agreement considering that the two values are steady under idealized conditions, which indicates their reasonable representation even in hot-dry areas. In general, air temperature and solar radiation are the main enhancing factors of heat stress, whereas wind speed and relative humidity are second-order drivers. This evidence is meaningful for climate-sensitive urban planning, public-health preparedness and scheduling of outdoor activities in the Iraqi region.