Dependence of model energy spectra on vertical resolution
MetadataShow full item record
Many high-resolution atmospheric models can reproduce the qualitative shape of the atmospheric kinetic energy spectrum, which has a power-law slope of −3 at large horizontal scales that shallows to approximately −5/3 in the mesoscale. This paper investigates the possible dependence of model energy spectra on the vertical grid resolution. Idealized simulations forced by relaxation to a baroclinically unstable jet are performed for a wide range of vertical grid spacings Δz. Energy spectra are converged for Δz 200 m but are very sensitive to resolution with 500 m ≤ Δz ≤ 2 km. The nature of this sensitivity depends on the vertical mixing scheme. With no vertical mixing or with weak, stability-dependent mixing, the mesoscale spectra are artificially amplified by low resolution: they are shallower and extend to larger scales than in the converged simulations. By contrast, vertical hyperviscosity with fixed grid-scale damping rate has the opposite effect: underresolved spectra are spuriously steepened. High-resolution spectra are converged except for the stability-dependent mixing case, which are damped by excessive mixing due to enhanced shear over a wide range of horizontal scales. It is shown that converged spectra require resolution of all vertical scales associated with the resolved horizontal structures: these include quasigeostrophic scales for large-scale motions with small Rossby number and the buoyancy scale for small-scale motions at large Rossby number. It is speculated that some model energy spectra may be contaminated by low vertical resolution, and it is recommended that vertical-resolution sensitivity tests always be performed.
Cite this version of the work
Michael L Waite (2016). Dependence of model energy spectra on vertical resolution. UWSpace. http://hdl.handle.net/10012/10538
Showing items related by title, author, creator and subject.
Nguyen, Khanh V. Q. (University of Waterloo, 2014-04-30)The full model of a double-wishbone suspension has more than 30 differential-algebraic equations which takes a remarkably long time to simulate. By contrast, the look-up table for the same suspension is simulated much ...
Mesoscale Hydrological Model Validation and Verification using Stable Water Isotopes: The isoWATFLOOD Model Stadnyk-Falcone, Tricia Anne (University of Waterloo, 2008-09-11)This thesis develops a methodology for mesoscale model verification and validation that is founded on the rigorous constraint imposed by the need to conserve both water mass and isotopes simultaneously. The isoWATFLOOD ...
Application of a Bi-Geometric Transparent Composite Model to HEVC: Residual Data Modelling and Rate Control Gao, Yueming (University of Waterloo, 2014-04-25)Among various transforms, the discrete cosine transform (DCT) is the most widely used one in multimedia compression technologies for different image or video coding standards. During the development of image or video ...