2003 Volume 59 Issue 2 Pages 155-164
Sensible heat advection from a 3-m-tall cornfield to a short grassland with a height of 0.3m was evaluated by wind speed and turbulent diffusivity, which were numerically calculated with a standard k-ε model including the effect of plant-atmosphere interaction, together with measured air temperature. The calculated wind speed agreed with the measurements. Air temperature was interpolated at each grid point by a bicubic spline method; the grid dataset of air temperature was used as a boundary condition to solve the advection-diffusion equation.At noon on a sunny day in late summer, air temperature showed a horizontally-decreasing distribution from the cornfield to the grassland and a vertical lapse over the grassland. Horizontal wind accelerated between the cornfield and grassland, and downward wind existed over the grassland. Under these conditions, the horizontal advection increased the vertical gradient of sensible heat flux ∂H/∂z, while the vertical advection decreased it. Since the horizontal advection was predominant, ∂H/∂z was generally positive. The effect of the vertical advection was significant near the leading edge. However, the effect decreased with downwind distance from the edge and was negligible near the grassland surface.