TWO-WAY COUPLING A REGIONAL CLIMATE MODEL WITH A HIGH RESOLUTION LAND SURFACE MODEL

摘要

To improve the overall simulations of the atmosphere and the land surface on the local scale in context of climate change, an approach was developed that fully couples the regional climate model MM5 (45×45 km) with the hydrological model PROMET (1×1 km). Therefore, the down- and upscaling tool SCALMET has been developed to overcome the scale mismatch between the coarser resolved atmosphere model and the one operating on the land surface. SCALMET conserves mass and energy within the downscaling of the meteorological data. PROMET calculates the massand energy fluxes of the land surface at high spatial resolution accounting for the natural heterogeneity. Subsequently, it provides the lower boundary condition of the regional climate model. This approach directly allows for mutual feedback effects with the atmosphere. Thus, the regional climate model benefits from the fine spatial resolution of the hydrological model and an advanced physical modelling of hydrological processes on the land surface. For example, the simulated near surface air temperature more closely matches the observed temperature for the Upper Danube catchment.