Abstract
Building induced winds change the falling of rain, leading to heterogeneous patterns of rain on ground and on building surfaces. These rain heterogeneities also occur in small urban scales like an urban neighbourhood, which covers an area of a few km2. For the investigation of rain heterogeneities within an urban neighbourhood the micro-scale, obstacle-resolving model MITRAS is used, which employs a microphysics parameterisation for cloud and rain processes. MITRAS has been extended by boundary conditions for cloud and rain water at building surfaces. An initialisation with radar data is implemented and the model output is successfully compared with in‑situ precipitation data. Simulations for an urban area are performed using different initial wind speeds, rain amounts, wind directions, and domain configurations. For the rain heterogeneity within this urban neighbourhood, the processes between buildings are found to be of small influence for the rain already falling. However, exchange processes from the canopy to the air above are found to influence the above-canopy rain pattern. The influence of the meteorological situation and the city's geometry on the wind field within and above the buildings are relevant to realistically represent a rain event and to create high-resolution precipitation data.
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