对流层物质垂直交换模式中的参数化处理

Parameterization Treatments of Vertical Exchange Model for Chemical Species in the Troposphere

为了研究对流层(TL)中垂直涡旋扩散系数(K_z)随高度变化的参数化形式对物质垂直交换的贡献,用“高分辨TL物质交换模式”(EM3)对5种不同K_z型进行了数值对比模拟,结果表明:KK_z型较好地描述了行星边界层(PBL)内受下垫面影响的高频湍流和PBL以上TL由各种动力学和热力学过程产生的切变湍流;垂直运动和K_z对PBL下层的物质输送到TL上层和从源高度向下输送到PBL低层两者均有重要作用;垂直运动的作用具有间隙性,而K_z是连续的.

In order to study the contributions of the parameterization forms of the variation of vertical eddy diffusivity (Kz)with height in the troposphere (TL) to the vertical exchange of chemical species, comparative numerical simulation for 5 different Kz patterns is carried out with 'high resolution mode! for species exchange within the troposphere' (EM3) and OSCAR 4. The results show that both high frequency turbulence influenced by the relative motion of the earth's surface in planetary boundary layer (PBL) and various shear turbulence derived from dynamical and thermodynamic processes in TL above PBL are better described by KKZ pattern; both vertical motion and Kz play an important role in transporting species from the lower PBL up to the upper TL and from the source level down to the bottom PBL; the vertical motion is intermittent in temporal and spatial distribution, but Kz is continuous in the whole TL. Kz can make greater contribution to vertical exchange of species than the mean vertical motion.