Characterization of the UHI in Zaragoza (Spain) using a quality-controlled hourly sensor-based urban climate network

The study of the urban heat island (UHI) is of great importance in the context of climate change, where increasingly frequent and intense extreme thermal events will generate lethal effects in cities. In this work, we characterize the UHI of the urban area of Zaragoza (Spain) using a thermohygrometric network of hourly observatories composed of 21 sensors, from March 2015 to February 2021. Due to the diversity of urban spaces and the high volume of information (approximate to 995,000 observations), we performed an exhaustive quality control. Incorporating a synoptic analysis to better identify atmospheric situations not recorded by sensors. The results indicate that 1.6% of observations are removed, mainly due to outliers and hourly variability. We demonstrate that the UHI displays the classical center-periphery pattern with intensity values around 2 degrees C, but with variations due to the urban structure. We also observe seasonal UHI variations that intensify, especially in winter and autumn nights. Finally, this characterization confirms the differences in UHI intensity are due to their structural and climatic characteristics, which can ultimately guide the logical urban planning design of Zaragoza, and other Mediterranean-like cities with a similar urban environment.

Automated summary

The study characterizes the urban heat island (UHI) in Zaragoza, Spain, and reveals its typical center-periphery pattern with an intensity of around 2 degrees Celsius. Seasonal variations in UHI were also observed. The study emphasizes the importance of considering urban structure and climatic characteristics when planning cities.