Turbulent Schmidt number estimate over urban canopies

This work presents laboratory estimates of the turbulent Schmidt number (Sct) above an idealized three-dimensional urban canopy. To do this, a neutral atmospheric boundary layer has been reproduced in the water channel and a staggered array of cubic obstacles of equal heights placed on the channel bottom has been used to simulate the canopy. A point source emitted a passive tracer at a constant rate above the cube array. Simultaneous measurements of pollutant concentration and velocity permitted the estimation of the vertical fluxes of mass and momentum and, therefore, of Sct. The results show a clear dependence of Sct on the height above the canopy.