Intermittency of Kolmogorov and coherent turbulence in the mountain boundary layer (overview)
V.V. Nosov1, V.P. Lukin1, P.G. Kovadlo2, E.V. Nosov1, A.V. Torgaev1
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2Institute of Solar-Terrestrial Physics of the Siberian Branch of the RAS, Irkutsk, Russia
Keywords: intermittency of turbulence, coherent turbulence, coherent structure, coherent turbulence spectrum, coherent structure spectrum, Kolmogorov and coherent turbulence relationship
Abstract
This overview is devoted to the intermittency of atmospheric turbulence of different types (of Kolmogorov and coherent) in the mountain boundary layer. A brief overview of the world scientific literature on the types of turbulence intermittency is made for a better understanding of the place of intermittency of different types among them. Due to available in literature various interpretations of the coherent turbulence concept, our earlier overviews of the world scientific literature on coherent turbulence and coherent structures are supplemented; these overviews describe the mechanisms of the origination (formation) of coherent turbulence and the key properties of coherent turbulence, as well as indicate the differences and relationships between the Kolmogorov and coherent turbulence. Discussion of the contemporary scientific understanding of turbulence structure can be attributed to the overviews results. Thus, the authors previously (2008-2019) independently showed that atmospheric turbulence can be considered as an incoherent mixture of various coherent structures. At the same time, there is a conjecture by E. Hopf (1948) about the finite dimensionality of attractors in the phase space of solutions of the Navier-Stokes equations. Physical interpretation of this conjecture, as pointed out by A.S. Monin and A.M. Yaglom (1991, 1992), is the representation of turbulence structure as a spatio-temporal chaos of a finite number of interacting coherent structures. From comparison of these representations, it can be seen that the authors’ results are in fact a proof of E. Hopf's conjecture in interpretation, formulated by A.S. Monin and A.M. Yaglom, and that the “chaos" of a turbulence is to a large extent determinate. The overview results of the study of the turbulence intermittency of different types are the consequent of many years experimental studies of turbulence by acoustic and optical methods performed by the authors at mountain astronomical observatories. Lifetimes of the turbulence different types: Kolmogorov and coherent, recorded in optical and meteorological measurements are given. It is shown that the effect of the intermittency of turbulence types characterizes the turbulence local structure over the observatory location region and allows to develop practical recommendations for the most favorable observation regime at astronomical observatories.
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