Verification and Case Studies for Urban Effects in HIRLAM Numerical Weather Forecasting

Abstract

In our study, the performance of the DMI HIgh Resolution Limited Area Models (HIRLAM)-U01/I01 research models (1.4 km horizontal resolution) with simple (urban roughness and anthropogenic heat flux) and complex (building effects parameterizations) urbanization were tested and verified. The simulations of the DMI-HIRLAM-U01/I01 without (i.e. the control run) and with the urbanized modules were performed in a short-term mode, i.e. for days with different meteorological conditions (such as typical and low winds), and in a long-term mode on a monthly basis. The comparison of the DMI-HIRLAM urbanized vs. control runs during the same period was performed. Detailed analyses of spatial and temporal variability of simulated conditions such as the wind characteristics, temperature and relative humidity over the metropolitan area of Copenhagen and surroundings were then completed. The diurnal variability of meteorological and derived characteristics over these urban areas was investigated. The verification of these characteristics was performed for selected urban/suburban stations located in the Copenhagen area.