Spatial patterns of the urban heat island in Zaragoza (Spain)

Spatial patterns of the urban heat island (UHI) in Zaragoza (Spain) were determined by Principal Component Analysis (VARIMAX rotation) of air temperature in the city, and mapped using GIS. The 3 components extracted accounted for 92.9% of the total variance. Principal component (PC) 1 accounted for the most general patterns of UHI, PC2 showed a shift of warm areas to the SE and PC3 a shift to the NW. A rotated component matrix was used to identify correlations between each component and daily maps. The spatial patterns indicated by PC2 and PC3 were determined by surface wind direction. The displacement of warm areas to the SE (PC2) was greater during NW winds while the shift to the NW (PC3) was produced mainly by SE winds.