The Urban Heat Island of a Mountainous Mediterranean City with a Desert Frontier; The Case of Jerusalem

Although the UHI has been widely investigated, UHI studies on cities in mountainous regions are limited. Previous studies have shown that mountainous cities in hot climates have unique environmental characteristics and relatively cool temperatures. Rapid urbanization followed by urban and global warming has begun to take a toll on the climatic conditions of these cities. Understanding the mechanism of the UHI in mountainous cities is challenging science due to the complex relationship between urban structure, urban landscape, varied topography and elevation.

The study aimed to monitor the formation of the Urban Heat Island (UHI) effect in Jerusalem, a city situated in a Mediterranean mountainous region near a desert frontier. The research sought to investigate the various landscape factors influencing spatial temperature variations, considering aspects such as landscape characteristics, local topo-climatic conditions, and elevation. Given the impact of complex urban topography on atmospheric conditions, the study aimed to identify systematic correlations between these factors and UHI intensity.

The methodological approach is an integrative one which includes multiple methods: Firstly, a Local Climate Zone (LCZ) classification. Secondly, meteorological observation data was collected based on official meteorological stations in and around Jerusalem. Thirdly, synoptic and atmospheric conditions are being studied using a semi-objective synoptic classification and meteorological and statistical tools.

Our findings demonstrate a strong correlation between synoptic conditions and the intensity of the urban heat island (UHI) in the Jerusalem mountains, governed by complex topographic influences and localized meteorological processes. During stable summer nights, UHI intensity can reach up to 6°C due to thermal inversions but may also be negligible, in accordance with the Israeli summer paradox. Unlike typical UHI dynamics, our results indicate that UHI in this region is more pronounced in summer than winter.