Development of a resolution-dependent parameterisation for surface fluxes with inclusion of sub-grid-scale land-use effects

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Evaporation from soil, water and vegetation is the source of water in the atmosphere. It depends an several factors; very relevant ones are atmospheric stratification and (subgrid-scale) land-use. This project aims to develop a resolution-dependent parameterisation for surface fluxes that considers subgrid-scale land-use effects. The parameterisation should work for grid sizes of 1 to 8 km for all meteorological situations. For developing the parameterisation the well-established mesoscale model METRAS will be used that already includes three different resolution-independent schemes to consider sub-gridscale land-use effects an the surface fluxes. Model performance will be rated by comparing with routine surface and flux measurements for meteorological situations that have a distinct difference in the relevance of local effects. This will be expressed by a newly introduced locality number lld which is also put in relation to the amount of precipitation. Idealised case studies with the obstacle resolving micro-scale model MITRAS will aid the parameterisation development. The parameterisation will be optimised for its use in weather forecast models. The new parameterisation will be implemented in LM and its performance be tested with respect to precipitation forecast.