Circumferential analysis of a simulated three-dimensional downburst-producing thunderstorm outflow

A high-resolution simulation of a downburst-producing thunderstorm has been conducted using a three-dimensional cloud model. The highly asymmetric near-ground outflow within the downburst has been analyzed within an axi-symmetric framework, by undertaking circumferential spatial averaging of the wind speed components, in order to explore whether the salient features of the outflow can be represented using the simpler models employed in wind engineering. The results indicate that this approach yields, at a given time during the event, outflow profiles that preserve the regions of the highest wind speed but do not preserve any flow structure. It is suggested that the peak radial wind speed around any circumference may be computed from the spatially-averaged mean multiplied by a consistent peak factor.