数值模式中气压梯度力的算法试验

本文在差微差一致性二阶精度的坐标变换公式的基础上,推导出了气压梯度力计算的新公式。同时,根据静力扣除法原理,提出了初值静力扣除法,用以计算有地形数值模式中的气压梯度力。将这两种新的方法与二阶计算精度的回插法和局地等温法(Corby格式)相比后发现:新方法(文中称为经典修正法)与回插法精度相近,但可节省计算时间,比局地等温法精度高。静力扣除法则效果较差,但其原因可能在于地转风垂直插值方法有误差。本文的试验模式是上海台风研究所的业务数值预报模式,文中对模式及若干技术处理也作了简要介绍。

EXPERIMENTS OF COMPUTATIONAL METHODS OF PRESSURE GRADIENT FORCE IN NUMERICAL MODELS WITH TOPOGRAPHY

New computational schemes of pressure gradient force are developed in this paper based on the coordinate transformation formula with difference-differential-difference consistence. In the mean time the so-called static subtraction method is suggested by using the initial field as the basic one. Several schemes are checked by some forecast experiments with real data. The results show that the new computational scheme is successful, but the initial static subtraction method is not as good as expected. The cause may be the errors in the vertical interpolations of the geostrophic wind.