Comment:

The vertical spread, was defined as one third of the plume width. The plume spread increases strongly within the vegetation, as the flow slows down due to drag, it expands in the vertical direction thus convecting the plume with it. In Region II, the plume spread growth rate decreases as the wake is characterized by low turbulence and velocity, hence there is no effective mechanism to disperse pollutants. In Region III, the plume width experiences an increase as a result of the turbulence and recirculation in the transition zone. That growth is maintained until the plume exits the high TKE region which extends to approximately to a height of 2.2H. After the plume exits that region, the effects of the vegetation becomes minimal, and the plume growth is predominantly dominated by the local atmospheric conditions. A linear fitting was chosen for each of the four regions as it describes the plume spread growth well, while keeping the model simple as highlighted in Figure 5b and Equations 12-15. The initial vertical spread, is integral as it provides the starting point for fitting the model.