Eighth Symposium on the Urban Environment
Boundary Layers and Turbulence Committee


Coherent structures within a North American street canyon

Sean C. Arms, Univ. of Oklahoma, Norman, OK; and P. M. Klein

The importance of coherent structures in the transport of heat and momentum within vegetative and urban canopies has been demonstrated and is well appreciated. It has been shown that coherent structures can account for up to nearly 90% of the kinematic heat and momentum fluxes in vegetative canopies, and similar results have been obtain in urban environments. In this study, street canyon data from the Joint Urban 2003 field campaign in Oklahoma City are used to estimate the importance of coherent structures within a North American street canyon. Velocity and temperature data from two towers located on opposing sides of Park Avenue in Oklahoma City are analyzed using conditional sampling techniques, such as quadrant analysis or a wavelet-based detection method. Results from conditional sampling techniques are used to assess the applicability of a Principal Component Analysis (PCA) based method for extracting information regarding coherent structures. This relatively new PCA based method has been used to extract information pertaining to boundary layer thermals, and results from previous studies suggest that PCA is a useful tool for studying coherent structures in the boundary layer. The applicability of the PCA method for the analysis of coherent structures in different urban canopy flow patterns, specifically along- and cross-canyon flows, is tested.

wrf recording  Recorded presentation

Joint Session 11, Urban Canopy and Roughness Sublayers
Monday, 12 January 2009, 4:00 PM-5:30 PM, Room 124B

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