Urban comfort dynamics in major megacities in the Middle East: A spatiotemporal assessment and linkage to weather types

Abstract

This study provides the first comprehensive assessment of the dynamics of urban comfort in the five largest megacities in the Middle East. The region's sparse and uneven meteorological station network has created a critical gap in urban climate research that addresses local urban spatial variability. Based on remote sensing data, we assessed changes in urban comfort for Cairo, Istanbul, Riyadh, Tehran, and Baghdad during the warm season (March–August) from 2003 to 2021. We employed NASA's Aqua satellite data to obtain high-resolution (1-km) Land Surface Temperature (LST) and Normalized Difference Moisture Index (NDMI) as proxies for air temperature and relative humidity, respectively. Results demonstrate that there has been a noticeable decline in areas with comfortable conditions and an increase in areas categorized as uncomfortable, particularly during nighttime and peak summer months (June–August). This rise in urban discomfort was more pronounced in extratropical cities such as Baghdad, Cairo, and Riyadh. LST warming during the warm season, especially at night, was the primary driver of urban discomfort, with humidity having a more limited impact. The results reveal a strong spatial alignment between the LST trends and the modified temperature-humidity index (MTHI), particularly at night. Results demonstrate that the impact of temperature and humidity on urban discomfort varies among cities. While the influence of humidity on urban discomfort was particularly significant in Baghdad, the effect of increasing temperatures was more evident in Istanbul and Tehran. These differences highlight the need for tailored and city-specific approaches to address the challenges posed by urban discomfort conditions. Also, we classified weather types corresponding to the intensified urban discomfort conditions using the Jenkinson and Collison method, employing sea level and 500 hPa pressure data from the ERA5 dataset. Results reveal that zonal and primarily western advections significantly contribute to urban discomfort in most cities, while anticyclonic conditions have a minimum effect. Overall, this study offers valuable insights into urban comfort levels in the Middle East, aiding urban climate adaptation and planning strategies in the region. Our method provides an innovative solution to assess urban comfort dynamics in data-scarce regions, including the Middle East and beyond.