9415003 Frenzen This research will evaluate changes in the equation for turbulent kinetic energy (TKE) in the surface layer as a function of roughness Reynolds number as well as stability by conducting and add-on experiment over an extensive forest in north central Saskatchewan. A 26-m tower temporarily installed in this location for the BOREAS experiment offers a timely opportunity to determine weather findings of earlier TKE studies conducted over selected "ideal" field sites also apply over more realistic terrain. Questions raised by recent experiments over two relatively smooth sites (zo < 5 cm) will be investigated over the much rougher forest canopy (zo> 50 cm) using proven procedures and equipment development for the earlier work. These questions include: a) How much does the difference between rates of turbulent energy production and dissipation (the dissipation deficit) changes with increasing roughness Reynolds number? b) How do the higher-order, turbulence and pressure transport terms adjust to these changes in the energy balance over rough surfaces? and c) Does the von Karman constant continue to decrease with roughness Reynolds number to the theoretical limit of 0.37? Results obtained will be used to develop generalized terms for applying the TKE equation to surface layer flows over real terrain, and will be used to determine the accuracy of various scaling hypotheses proposed for flow over forests.
