An Evaluation of the Canopy Layer Urban Heat Island Through Regional Air Temperatures in Cheltenham, Gloucestershire, 1990 to 2000

The urban heat island (UHI) is the difference in equivalent temperatures of a city when compared with its rural surroundings. Interactions between natural and anthropogenic activity have been proposed as key driving mechanisms towards UHIs, and this is often exacerbated by anticyclonic conditions and extreme weather phenomena. Typical studies of the UHI focus on populous and mega-cities rather than smaller towns and cities. The aim of this study was to investigate what factors help to explain why Cheltenham was ranked the hottest town in the United Kingdom (UK) between the years 1990 to 2000 and to what extent the effects of weather and the natural and artificial landscape influenced the magnitude and geographical extent of the UHI in Cheltenham. Data from MIDAS weather stations in Gloucestershire were used for statistical analyses to test and infer the associations between the canopy layer urban heat island (CUHI) in Cheltenham and cloud cover, precipitation, population, and changes in land cover between 1990-2000. Sunspot cycles were used as an experimental surrogate for solar intensity. Air temperature profiles show Cheltenham demonstrates higher temperatures when compared with its rural surroundings with temperatures exceeding 3.43°C (maximum) and 0.95°C (minimum). Correlation analyses show that cloud cover has a significant, weak, negative correlation with maximum and minimum CUHI. The CUHI shows a weak negative correlation with precipitation. In addition, CUHI minimum shows a strong, significant relationship with population growth. This study concludes that small towns and cities demonstrate an urban heat island effect. Furthermore, that Cheltenham’s CUHI is conditioned by fluctuations in cloud cover, precipitation, and changes in population over time