Abstract
In this study, characteristics of the energy spectrum in the zonal wavenumber domain are examined for the cloud resolving global model NICAM. A series of numerical experiments are conducted for NICAM with various horizontal resolutions from 224 km (glevel-5) to 7.0 km (glevel-10) using the T2K-Tsukuba System and 3.5 km (glevel-11) using the Earth Simulator (ES). The energy spectra of most of horizontal resolutions obey k-3 power law in synoptic and sub-synoptic scales (wavenumbers k = 5 to 30). However, the energy slope for glevel-5 becomes much steeper around zonal wavenumber k = 10. Nastrom et al. (1985) explained that the energy spectrum near the tropopause at wavelengths below 400 km appears to follow the k-5/3 power. This scale corresponds to about k = 70 near 45°N. It is found that the energy spectra for k > 30 for glevel-10 and 11 follow the k-5/3 power law. These results agree quite well with the observational studies. It is also found that the kinetic energy of the vertical wind is white noise spectrum.
