A HIGH RESOLUTION MODEL FOR CHEMICAL SPECIES EXCHANGE IN TROPOSPHERE

Based on the regional acid deposition model(RADM),a high resolution model for species exchange in the troposphere(EM3) is designed.EM3 differs considerably in the following 5 aspects from RADM.First,the vertical grid levels in the planetary boundary layer(PBL) are increased.Second,layered vertical eddy diffusivity patterns in the troposphere(TL) are considered.Third,layered horizontal eddy diffusivity patterns within TL is used.Fourth,new dry deposition velocity pattern including the effect of plant canopy layer(CL) vertical structure is adopted.Fifth,advective scheme of second-order moment conservation with less numerical diffusion is used.OSCAR 4 case is comparatively simulated with both EM3 and RADM.The results show that 3-D distribution laws of chemical species in whole TL are forecasted by EM3 better than by RADM.Under the same conditions,all ratios of the central concentrations simulated with both models in lower PBL are more than 1.8,the maximum can be more than 3.