Determination of Persistence Effects in Spatio-temporal Patterns of Upward Long-wave Radiation Flux Density from an Urban Courtyard by Means of Time-sequential Thermography

This research analyses upward long-wave radiation flux density from urban surfaces using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. We report spatiotemporal patterns of the difference between upward long-wave radiation flux density from courtyard surfaces and the roof. Thermal patterns show persistence effects due to shadow, sky view factor (SVF) distribution, thermal properties of surface materials, human activities and turbulence characteristics of the surface-atmosphere interface. The attenuation of thermal patterns caused by temporary disturbances due to parked cars can be described by a modified exponential curve and a time-constant. This study shows that ground-based highresolution TIR imagery is highly suitable to investigate dynamic processes controlling thermal patterns within a complex three-dimensional urban structure.