DISPERSÃO DE POLUENTES EM AMBIENTE DE CAMADA PRÉ-RESIDUAL E ESTÁVEL USANDO UM MODELO LAGRANGEANO DE VELOCIDADE ALEATÓRIA

The Planetary Boundary Layer is directly influenced by the the surface forcing and the heating/cooling due to radiation fluxes. Consequently, when this flow becomes negative, the development of a stable boundary layer near the surface and a pre-residual layer above occurs. The aim of this paper is to simulate the dispersion patterns of pollutants emitted from two continuous point sources (60 m and 120 m) using a model of Lagrangian particles of Random Speed during sunset. For the continuous point source of 60 m, the results show that initially the low depth of the stable boundary layer associated to the decaying convective energy inside the pre-residual layer contributed to the effective entry of the pollutant into its interior and its surface concentration. When the pollutant is emitted in a totally stable environment, it decreases its concentration on the surface, forming a fanning plume type. For the continuous point source with a height of 120 m, the simulations show that for the pollutant emitted always in a pre-residual layer environment, there is initially a concentration on the surface and an increase as it keeps distance from the source. Subsequently, with the increase of the depth of the stable boundary layer, the maximum concentration moves towards to near its top, where the concentration values increase.