非静力平衡模式的中尺度非均匀初始场试验和锋面模拟

TEST OF NONHYDROSTATIC MODEL BY USING MESOSCALE NONHOMOGENEOUS INITIAL FIELDS AND SIMULATION OF FRONT CASE

用非静力平衡二维中β－γ尺度大气模式，选取１９８７年欧洲的一次冷锋过程为个例，以法国的静力平衡模式的模拟结果为初始场，选用５ｋｍ，２５ｋｍ，４５ｋｍ３种水平格距进行了水平范围为２０００ｋｍ的模拟，结果表明：（１）中尺度非静力平衡模式应用非均匀初始场，而不加人为的初始扰动是可行的；（２）扰动量的初始场中π′的精度要求很高，应严格符合静力平衡条件，否则就会产生严重误差，甚至在一个时步内改变垂直速度；（３）５ｋｍ，２５ｋｍ，４５ｋｍ３种格距的对比模拟表明，５ｋｍ格距的非静力平衡模式能模拟出锋面上的多个中β尺度对流，且垂直速度场分布与实际最接近，而后两种格距只能模拟出锋面上的大范围上升区，不能细致地描述锋面对流结构。

wodimension nonhydrostatic βγ mesoscale atmospheric model is used to simulate an European cold frontal process in 1987 ,whose initial fields come from a hydrostatic model.The horizontal extension is 2000 km and three different horizontal resolutions 5 km, 25 km,and 45 km are used. The results show:1 ) It is practical for a mesoscale nonhydrostatic model to use nonhomogeneous initial fields, without an artificial disturbance cell added.2 )The initial fields of the disturbed quantity( pressure π′),should follows the principle of hydrostatic balance strictly,otherwise it can consult in great acceleration , so far as to change the vertical velocity field completely in a short time step.3 )Nonhydrostatic model with grid length of 5 km can get several mesoscale convective cells on the front,and the distribution of vertical velocity are similar to the reality,while the model with larger resolutions( 25 km and 45 km ) can only describe a wide updraft associated with front.