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‘Application of a New Spectral Theory of Stably Stratified Turbulence to the Atmospheric Boundary Layer over Sea Ice’ 总被引：7，自引：5，他引：2
Semion?Sukoriansky Boris?GalperinEmail author Veniamin?Perov 《Boundary-Layer Meteorology》2005,117(2):231-257
A new spectral closure model of stably stratified turbulence is used to develop a K–ε model suitable for applications to the atmospheric boundary layer. This K–ε model utilizes vertical viscosity and diffusivity obtained from the spectral theory. In the ε equation, the Coriolis parameter-dependent formulation of the coefficient C 1 suggested by Detering and Etling is generalized to include the dependence on the Brunt-Väisälä frequency, N. The new K–ε model is tested in simulations of the ABL over sea ice and compared with observations from BASE as simulated in large-eddy simulations by Kosovic and Curry, and observations from SHEBA. 相似文献
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Geophysical flows with anisotropic turbulence and dispersive waves: flows with stable stratification
The quasi-normal scale elimination (QNSE) is an analytical spectral theory of turbulence based upon a successive ensemble
averaging of the velocity and temperature modes over the smallest scales of motion and calculating corresponding eddy viscosity
and eddy diffusivity. By extending the process of successive ensemble averaging to the turbulence macroscale one eliminates
all fluctuating scales and arrives at models analogous to the conventional Reynolds stress closures. The scale dependency
embedded in the QNSE method reflects contributions from different processes on different scales. Two of the most important
processes in stably stratified turbulence, internal wave propagation and flow anisotropization, are explicitly accounted for
in the QNSE formalism. For relatively weak stratification, the theory becomes amenable to analytical processing revealing
just how increasing stratification modifies the flow field via growing anisotropy and gravity wave radiation. The QNSE theory
yields the dispersion relation for internal waves in the presence of turbulence and provides a theoretical reasoning for the
Gargett et al. (J Phys Oceanogr 11:1258–1271, 1981) scaling of the vertical shear spectrum. In addition, it shows that the internal wave breaking and flow anisotropization
void the notion of the critical Richardson number at which turbulence is fully suppressed. The isopycnal and diapycnal viscosities
and diffusivities can be expressed in the form of the Richardson diffusion laws thus providing a theoretical framework for
the Okubo dispersion diagrams. Transitions in the spectral slopes can be associated with the turbulence- and wave-dominated
ranges and have direct implications for the transport processes. We show that only quasi-isotropic, turbulence-dominated scales
contribute to the diapycnal diffusivity. On larger, buoyancy dominated scales, the diapycnal diffusivity becomes scale independent.
This result underscores the well-known fact that waves can only transfer momentum but not a scalar and sheds a new light upon
the Ellison–Britter–Osborn mixing model. It also provides a general framework for separation of the effects of turbulence
and waves even if they act on the same spatial and temporal scales. The QNSE theory-based turbulence models have been tested
in various applications and demonstrated reliable performance. It is suggested that these models present a viable alternative
to conventional Reynolds stress closures. 相似文献
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Ocean Dynamics - Seasonal variability of the upper ocean on meso- and submesoscales is investigated in the framework of the quasi-normal scale elimination theory, or QNSE. The longitudinal and... 相似文献
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Geostrophic turbulence is a key paradigm in the current understanding of the large-scale planetary circulations. It implies
that a flow is turbulent, rotating, stably stratified, and in near-geostrophic balance. When a small-scale forcing is present,
geostrophic turbulence features an inverse energy cascade. When the meridional variation of the Coriolis parameter (or a β-effect) is included, the horizontal flow symmetry breaks down giving rise to the emergence of jet flows. The presence of
a large-scale drag ensures that the flow attains a steady state. Dependent on the governing parameters, four steady-state
flow regimes are possible, two of which are considered in this study. In one of these regimes, a flow is dominated by the
drag while in the other one, the recently discovered regime of zonostrophic turbulence, a flow becomes strongly anisotropic
and features slowly evolving systems of alternating zonal jets. Zonostrophic turbulence is distinguished by anisotropic inverse
energy cascade and emergence of a new class of nonlinear waves known as zonons. In addition, meridional scalar diffusion is
strongly modified in this regime. This paper provides an overview of various regimes of turbulence with a β-effect, elaborates main characteristics of friction-dominated and zonostrophic turbulence, elucidates the physical nature
of the zonons, discusses the meridional diffusion processes in different regimes, and relates these results to oceanic observations. 相似文献
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