Effect of sharp vegetation boundary on the convective atmospheric boundary layer

An abrupt change of turbulent fluxes and cloud formation were found during the Bunny Fence experiment in the southwestern Australia at a sharp boundary between agricultural and native vegetation. It is suggested that this is a direct consequence of distinct coherent structures formed within atmospheric sheared convective boundary layers. Using large-eddy simulations (LES), it was found that a boundary-attached roll circulation appears at the sharp vegetation boundary. Model calculations revealed significant horizontal heat and moisture flux from the agricultural to the native vegetation area. The additional moisture flux may explain the observed increased cloud formation over the native vegetation as well as contribute to increased rainfall over the native vegetation.