To minimize the number of vertical layers and subsequently the computational cost, an integral method of the vertical momentum equation at the top-layer is applied to account for the full effects of non-hydrostatic pressure at the free-surface layer. 为了减少垂向分层以及计算代价,在表层采用对垂向动量方程积分的方式确保了表层非静压的影响精确给出。