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- Title
Kelvin-Helmholtz Instability "Tube" and "Knot" Dynamics. Part II: KHI T&K Dynamics in a Multiscale Gravity Wave Direct Numerical Simulation.
- Authors
FRITTS, DAVID C.; LING WANG
- Abstract
A companion paper by Fritts et al. reviews evidence for Kelvin-Helmholtz instability (KHI) "tube" and "knot" (T&K) dynamics that appear to be widespread throughout the atmosphere. Here we describe the results of an idealized direct numerical simulation of multiscale gravity wave dynamics that reveals multiple larger- and smaller-scale KHI T&K events. The results enable assessments of the environments in which these dynamics arise and their competition with concurrent gravity wave breaking in driving turbulence and energy dissipation. A larger-scale event is diagnosed in detail and reveals diverse and intense T&K dynamics driving more intense turbulence than occurs due to gravity wave breaking in the same environment. Smaller-scale events reveal that KHI T&K dynamics readily extend to weaker, smaller-scale, and increasingly viscous shear flows. Our results suggest that KHI T&K dynamics should be widespread, perhaps ubiquitous, wherever superposed gravity waves induce intensifying shear layers, because such layers are virtually always present. A second companion paper demonstrates that KHI T&K dynamics exhibit elevated turbulence generation and energy dissipation rates extending to smaller Reynolds numbers for relevant KHI scales wherever they arise. These dynamics are suggested to be significant sources of turbulence and mixing throughout the atmosphere that are currently ignored or underrepresented in turbulence parameterizations in regional and global models.
- Subjects
HELMHOLTZ, Hermann von, 1821-1894; KELVIN-Helmholtz instability; GRAVITY waves; ENERGY dissipation; COMPUTER simulation; SHEAR flow
- Publication
Journal of the Atmospheric Sciences, 2023, Vol 80, Issue 10, p2439
- ISSN
0022-4928
- Publication type
Article
- DOI
10.1175/JAS-D-22-0193.1