OBSERVATIONS AND LARGE-EDDY SIMULATION MODELING OF FOOTPRINTS IN THE LOWER CONVECTIVE BOUNDARY-LAYER

Scalar source footprint predictions inside and above the unstable surf ace layer are performed using a large-eddy simulation (LES) model. LES footprint results were evaluated against a tracer field experiment at one level and against other models beyond the 10 m measurement level in the surface layer. This paper further reports on an extension of th e range over which current footprint models can be used by presenting LES calculations of flux mapping to the downwind region from the sourc e location beyond the surface layer. Our LES flux mapping results show a gradual decoupling with increasing distance from the surface. Our r esults also indicate that the footprints, cumulative fluxes, and conce ntration distributions calculated using LES in unstable conditions are in general agreement with field observations and with those of other models. The present work shows promise for the use of LES as a tool to model more complex footprint cases such as those over heterogeneous s urfaces.