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.
Model Refinement and Reduction for the Nitroxide-Mediated Radical Polymerization of Styrene with Applications on the Model-Based Design of Experiments Hazlett, Mark Daniel (University of Waterloo, 2012-09-26)Polystyrene (PS) is an important commodity polymer. In its most commonly used form, PS is a high molecular weight linear polymer, typically produced through free-radical polymerization, which is a well understood and robust ...
Calibration and Model Uncertainty of a Two-Factor Mean-Reverting Diffusion Model for Commodity Prices Chuah, Jue Jun (University of Waterloo, 2013-08-28)With the development of various derivative instruments and index products, commodities have become a distinct asset class which can offer enhanced diversification benefits to the traditional asset allocation of stocks and ...
De Abreu, Pedro Felipe (University of Waterloo, 1997)