Climatology of wind, kinetic energy and temperature spectra using a high-resolution climate model for mid-Europe

Spectra of wind, kinetic energy, and temperature are investigated for a dataset of 10 years of regional climate simulations for mid-Europe. The nonhydrostatic Consortium for Small-Scale Modeling (COSMO) model in Climate Mode [COSMO-CLM (CCLM)] climate model is used in a hindcast mode for 1991-2000. The threestep nesting chain starts with a CCLM run with 18-km resolution covering all of Europe nested in ERA-40 reanalyses and then a run with a resolution of 4.4km is performed for mid-Europe. Finally, the 1.3-km run focuses on the region of mid-Germany and Luxembourg. In the present study, only results for the 4.4-and 1.3-km runs are shown. Different methods based on the Fourier and cosine transformations for the computation of the spectra are evaluated. The kinetic energy spectra showthe expected -5/3 slope in the mesoscale (up to the effective resolution), while the spectrum of the vertical wind shows a zero-slope behavior. The spectra of the horizontal wind components and temperature compare well to the observations. The effective model resolution was found to be about 7-10 (5-7) times the horizontal grid spacing for the one-dimensional (two-dimensional) spectral methods. A comparison between the differentmodel resolutions shows a benefit of the 1.3-km simulations for the boundary layer for horizontal scales up to 25 km. The multiyear time-scale simulations allow for a climatological study of the seasonal cycle. The kinetic energy spectrum is found to have the largest values in summer.