Micro-scale variability of air temperature within a local climate zone in Berlin, Germany, during summer

Abstract

The urban climate, especially the near-surface air temperature (T), is influenced to large amounts by urban surface properties on the local-scale. Landscape classification schemes, like the Local Climate Zone (LCZ) concept, classify neighbourhoods on this scale based on their surface properties, neglecting sub-scale heterogeneity in the urban structure and its potential effects on T. To quantify sub-scale T variability, a measurement campaign with eleven stationary T sensors was conducted within one LCZ (class 2B, compact midrise with scattered trees) in Berlin, Germany, during 22 days in summer 2016. Correlation analyses were performed between observed spatial T differences and micro-scale morphometric parameters around the measurement sites, such as sky view factor and building surface fraction. The results show mean night-time T differences of up to 1 K between the different sites. On a clear, calm and dry day, the daytime difference reached 3 K. At night-time, the variability can be best explained by the building surface fraction within a radius of 50 m. Further, a nocturnal cooling influence of a neighbouring green space could be observed. The observed micro-scale T variability was smaller than T differences to other LCZ classes, highlighting the applicability of the LCZ concept.