Effect of the nonuniform grid on the two-dimensional transport equation was investigated in terms of theoretical analysis and finite difference method (FDM). The nonuniform grid having a typical structure of the numerical weather forecast model was incorporated in the vertical direction, while the uniform grid was used in the zonal direction. The staggered and non-staggered grid were placed in the vertical and zonal direction, respectively. Time stepping was performed with the third-order Runge Kutta scheme. An error analysis of the spatial discretization on the nonuniform grid was carried out, which indicated that the combined effect of the nonuniform grid and advection velocity produced either numerical diffusion or numerical adverse-diffusion. An analytic function is used for the quantitative evaluation of the errors associated with the discretized transport equation. Numerical experiments with the non-uniformity of vertical grid were found to support the analysis.

Introduction
 Transport Equation andBoundary Conditions
 Discretization Method
 Initial Condition, Analytic Solution,and Model Parameters
 Results and Discussion
 Concluding Remarks
 Acknowledgments
 References

• Chung-Hui Lee(Department of Environmental Atmospheric Sciences, Pukyong National University)
• Hyeong-Bin Cheong(Department of Environmental Atmospheric Sciences, Pukyong National University) Corresponding author
• Hyun-Ju Kim(Department of Environmental Atmospheric Sciences, Pukyong National University)
• Hyun-Gyu Kang(Department of Environmental Atmospheric Sciences, Pukyong National University, BK21 plus Project of the Graduate School of Earth Environmental Hazard System)