Saltation layers, vegetation canopies and roughness lengths
This paper argues that vegetation canopies offer an analogue for saltation layers in that both flows have similar momentum sink distributions (from the fluid). Therefore, information on turbulence and momentum transfer in vegetation canopies provides guidance for turbulence in saltation layers. Working from the simplest gradient-diffusion theory for momentum transfer known to be useful in vegetation canopies, the paper explores a first-order theory for fluid momentum transfer in a saltation layer. This leads to an analytic expression for the overall momentum absorption capacity or roughness lenth z 0 S of the saltation layer, different from previous suggestions and in agreement with field observations of saltation.
KeywordsMomentum Transfer Particle Trajectory Roughness Length Wind Profile Vegetation Canopy
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