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Multi-scale waves in sound-proof global simulations with EULAG
Acta Geophysica
  • Joseph Prusa, Teraflux Corporation
  • William Gutowski, Iowa State University
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EULAG is a computational model for simulating flows across a wide range of scales and physical scenarios. A standard option employs an anelastic approximation to capture nonhydrostatic effects and simultaneously filter sound waves from the solution. In this study, we examine a localized gravity wave packet generated by instabilities in Held-Suarez climates. Although still simplified versus the Earth’s atmosphere, a rich set of planetary wave instabilities and ensuing radiated gravity waves can arise. Wave packets are observed that have lifetimes ≤ 2 days, are negligibly impacted by Coriolis force, and do not show the rotational effects of differential jet advection typical of inertia-gravity waves. Linear modal analysis shows that wavelength, period, and phase speed fit the dispersion equation to within a mean difference of ∼ 4%, suggesting an excellent fit. However, the group velocities match poorly even though a propagation of uncertainty analysis indicates that they should be predicted as well as the phase velocities. Theoretical arguments suggest the discrepancy is due to nonlinearity — a strong southerly flow leads to a critical surface forming to the southwest of the wave packet that prevents the expected propagation.

This article is from Acta Geophysica. Volume 59, Issue 6, Pages 1135–1157, ISSN (Online) 1895-7455, ISSN (Print) 1895-6572, DOI: 10.2478/s11600-011-0050-0, October 2011

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0)
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Institute for Geophysics, Polish Academy of Sciences
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Joseph Prusa and William Gutowski. "Multi-scale waves in sound-proof global simulations with EULAG" Acta Geophysica Vol. 59 Iss. 6 (2011) p. 1135 - 1157
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