Effects of urban land use on surface temperature in Berlin: Case study

Surface temperature as an important factor in urban microclimate is studied to provide quantitative information on the effects of the degree of surface sealing and vegetated surfaces for purposes of integrated urban planning. The effect of small-scale land use on surface temperature is obtained in some detail by means of airborne surface thermometry and block-related data on urban land use for the city of Berlin during the Berlin Ozone Experiment (BERLIOZ) in 1998. For two hot summer days (July 20-21, 1998), the portions of surfaces covered with vegetation, sealed, and the type of building structure are shown to be what is mainly controlling surface temperature. During midday on July 20, the traffic areas (except for streets) developed a highest surface temperature of approximately 41 degrees C. Streets, on the other hand, have a 4 degrees C lower surface temperature due to partial shading by buildings. Water surfaces have the lowest surface temperatures of approximate to 26 degrees C during midday, followed by parks and green areas with approximate to 33 degrees C. The surface temperature correlates positively with the percentage of sealed surfaces within blocks. The linear regression coefficient rises from 0.1 K/10% in the early morning to 0.8K/10% during maximum insolation. The measured surface temperatures are extrapolated to the whole area of Berlin by means of the regression coefficients of sealed surfaces being built up or not built up. The rise of the surface temperature toward the city center in the morning and afternoon is in qualitative agreement with surface temperature maps obtained from Landsat data in 2001, taking the different acquisition times into account.