物质输运方程中平流项数值格式的改进

Numerical Scheme Improvement of the Advection Term in Mass Transport Equation

在水平曲线坐标和垂向σ坐标的三维海洋模式下,欧拉-拉格朗日方法的插值如果在σ-面相邻网格之间进行,那么在水深变化剧烈处,由于σ-面相邻网格之间的垂向距离较大,插值依据会显得较不合理．所以把插值改在绝对坐标下进行．数值试验表明,改进后的欧拉-拉格朗日方法在水深变化剧烈处比改进前的数值耗散更小、精度更高和表现更合理．

In a three-dimensional ocean model with curvilinear coordinates horizontally and σ coordinate vertically, the adapted grids at σ layer for interpolation in the Eulerian-Lagrangian Method （ELM） is unreasonable over steep topography, because the vertical distance between the adjacent grids in the same σ layer is too large. So this paper proposed that the interpolation is taken in absolute vertical coordinates to improve ELM. Compared with the original ELM, the numerical experiments show that the improved ELM has lower numerical dissipation, higher accuracy, and better performance over steep topography.