= The Urban Microscale Model Intercomparison Project (UMMIP) = A computational fluid dynamics model intercomparison for building-resolving simulation of the urban atmospheric boundary layer. == Motivation == Over the past decades, urban microscale models have been increasingly used to simulate the urban atmosphere. Today, a multitude of models exist that differ in complexity, employed parameterizations, and degree of parallelization. While simple model configurations (i.e. simple building configurations, steady-state conditions, and no thermodynamics) have been often validated against wind tunnel experiments, the evaluation of more complex configurations is difficult. The reason is that wind tunnels are not able to take into account complex processes like radiative transfer, non-stationary conditions, and complex thermodynamic interactions with the urban surfaces. By the same token, real urban environments are too complex to be aggregated in data sets based on field experiments. A validation based on such data sets is thus impossible. The UMMIP aims at providing a comprehensive data set based on multi-model simulations for well-defined set-ups in urban environments. The complexity of the set-ups is increased in several stages based on existing and newly-developed set-ups suitable to be simulated by most of the participating models. UMMIP also aims at investigating the spread in the results between different models and how they might be related to the model physics, numerics, and parameterizations. Finally, we also strive at providing detailed information about model optimization in terms of degree of parallelization and performance. == Setups == The setups are XXX, YYY, and ZZZ and are described in detail [wiki:/ucmip/setups here]. == Input Requirements == The input requirements are described in detail [wiki:/ucmip/input here]. == Output Requirements == The output requirements are described in detail [wiki:/ucmip/output here].