Characteristics of the Kinetic Energy Spectrum of NICAM Model Atmosphere

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.

Erratum: Energy Spectra of Rossby and Gravity Waves [SOLA Vol.7(2011), pp.45-48]

“…The result of this study may indicate that the shifting wavenumber from k −3 to k −5/3 is determined just as a crossing wavenumber of Rossby wave and gravity wave spectra. Terasaki et al (2009) found that the energy spectrum of the vertical motion becomes white noise using NICAM experiment (3.5 km horizontal grid spacing), which has almost the same energy level at any horizontal scales. It is suggested that the k −5/3 power spectral law in stratified turbulence may be explained by the saturation theory of the vertical motion.…”

“…According to their results, the nonlinear interactions between geostrophic and gravitational modes play a crucial role in the downscale energy cascades for forming the k −5/3 spectrum. Terasaki et al (2009) showed the kinetic energy spectra for zonal wind and vertical wind components simulated by NICAM (Non-hydrostatic ICosahedral Atmospheric Model) with horizontal grid spacing from 224 km to 3.5 km. They confirmed that the spectra of zonal wind components follows k −5/3 law in the mesoscale for 7.0 km and 3.5 km experiments.…”

The Non-hydrostatic Icosahedral Atmospheric Model: description and development

“…The convective structure near the tropopause was also analyzed by Kubokawa et al (2012). The energy spectrum and similar frequency spectra of the high-resolution data were analyzed by Terasaki et al (2009) and Tsuchiya et al (2011).…”

Characteristics of the JRA-55 and ERA-Interim Datasets by Using the Three-Dimensional Normal Mode Energetics

“…Likewise, Žagar et al (2009a, b) applied the 3D normal mode energetics to four different analyses and compared energy levels of gravity modes. With regard to model output, Terasaki et al (2009) investigated the details of the kinetic energy spectrum of Non-hydrostatic Icosahedral Atmospheric Model (NICAM) for different resolutions by using Fourier analysis, and they showed that the highest resolution model can exhibit the shift of the energy slopes from the -3 power to -5/3 power laws.…”