E1. Mean Velocity Profile in a Sheared and Thermally Stratified Atmospheric Boundary Layer

Katul, Gabriel G.; Konings, Alexandra; Porporato, Amilcare

E1. Mean Velocity Profile in a Sheared and Thermally Stratified Atmospheric Boundary Layer

dc.contributor.author	Katul, Gabriel G.
dc.contributor.author	Konings, Alexandra
dc.contributor.author	Porporato, Amilcare
dc.date.accessioned	2012-07-20T17:10:28Z
dc.date.available	2012-07-20T17:10:28Z
dc.date.issued	2012-05
dc.description	Once downloaded, these high definition QuickTime videos may be played using a computer video player with H.264 codec, 1280x720 pixels, millions of colors, AAC audio at 44100Hz and 29.97 frames per second. The data rate is 5Mbps. File sizes are on the order of 600-900 MB. (Other formats may be added later.) Free QuickTime players for Macintosh and Window computers may be located using a Google search on QuickTime. The DVD was produced by J. Robert Cooke.	en_US
dc.description.abstract	Most human activity and biological processes occur within the lower atmosphere, a thermally stratified region characterized by shear and buoyancy-driven turbulence. Thermal stratification arises because of diurnal heating and cooling resulting in finite sensible heat flux at the Earth’s surface, while turbulence is mechanically produced due to the reduced mean velocity near the ground. The coexistence of shear- and buoyancy-generated turbulence leads to many difficulties in describing the flow properties in the lower atmosphere. Even for a stationary, horizontally homogeneous, high Reynolds number flow above an infinite flat and heated (or cooled) surface, the description of elementary flow statistics such as the mean velocity profile (MVP) has resisted complete theoretical treatment. There are inklings of a possible universal behavior in the MVP across a wide range of thermal stratification conditions as demonstrated by the collapse of data from multiple field experiments using dimensional analysis, known as Monin-Obukhov similarity theory. The Monin-Obukhov similarity framework has shaped micrometeorology and surface hydrology for more than 60 years now, and it remains the corner stone of virtually every single textbook on lower-atmospheric turbulence. The stability correction functions (SCF) are used in all climate, atmospheric, air quality, hydrologic, and ecological applications, including models of land-surface processes when land-surface fluxes are to be coupled to the state of the atmosphere. Yet, despite the SCF’s wide usage, even phenomenological theories that predict their canonical shape are still lacking. A previous link between the spectrum of turbulence and the MVP is expanded here to include the effects of thermal stratification on the turbulent kinetic energy dissipation rate and eddy-size anisotropy. The resulting theory provides a novel explanation for the power-law exponents and coefficients of MVP already reported from numerous field experiments. When taken together with a similar derivation for Manning’s equation and the Reynolds number dependence of the Nikuradse friction-factor, a blueprint for a unifying theory that bridges the Kolmogorov turbulent kinetic energy spectrum to widely used empirical results describing high Reynolds number flows in hydrology is beginning to unfold.	en_US
dc.description.viewer	1_e5rwa12h	en_US
dc.identifier.uri	https://hdl.handle.net/1813/29562
dc.publisher	Internet-First University Press	en_US
dc.title	E1. Mean Velocity Profile in a Sheared and Thermally Stratified Atmospheric Boundary Layer	en_US
dc.type	video/moving image	en_US

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E1. Mean Velocity Profile in a Sheared and Thermally Stratified Atmospheric Boundary Layer

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